File: README.md

package info (click to toggle)
libsixel 1.8.6-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 13,632 kB
  • sloc: ansic: 23,497; sh: 8,443; cpp: 1,227; python: 526; makefile: 444; xml: 271; ruby: 31; perl: 26
file content (1548 lines) | stat: -rw-r--r-- 56,389 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
libsixel
========

[![Build Status](https://travis-ci.org/saitoha/libsixel.svg?branch=master)](https://travis-ci.org/saitoha/libsixel)
[![Coverage Status](https://coveralls.io/repos/saitoha/libsixel/badge.png?branch=master)](https://coveralls.io/r/saitoha/libsixel?branch=master)

## What is this?

This package provides encoder/decoder implementation for DEC SIXEL graphics, and
some converter programs.

![img2sixel](https://raw.githubusercontent.com/saitoha/libsixel/data/data/libsixel-1.png)(https://youtu.be/0SasrQ7pnbA)

SIXEL is one of image formats for printer and terminal imaging introduced by
Digital Equipment Corp. (DEC).
Its data scheme is represented as a terminal-friendly escape sequence.
So if you want to view a SIXEL image file, all you have to do is "cat" it to your terminal.

On 80's real hardware terminals, it tooks unbearable long waiting times to display images.

[![vt330sixel](https://raw.githubusercontent.com/saitoha/libsixel/data/data/vt330sixel.png)](https://youtu.be/0SasrQ7pnbA)

But nowdays, with high-speed CPU and broadband network, we got the chance to develop a new scope of SIXELs.

## SIXEL Animation

`img2sixel(1)` can decode GIF animation.

  ![Animation](https://raw.githubusercontent.com/saitoha/libsixel/data/data/sixel.gif)


## Related projects

### Video streaming

Now Youtube video streaming is available over SIXEL protocol by [FFmpeg-SIXEL](https://github.com/saitoha/FFmpeg-SIXEL) project.

  [![FFmpeg-SIXEL](https://raw.githubusercontent.com/saitoha/libsixel/data/data/ffmpeg.png)](http://youtu.be/hqMh47lYHlc)

Above demo only uses 16 color registers.

### SDL integration: Gaming, Virtualization, ...etc.

[SDL1.2-SIXEL](https://github.com/saitoha/SDL1.2-SIXEL) project makes enable you to operate various GUI applications on the terminal.

You can play "`The Battle for Wesnoth`" over SIXEL protocol.

  [![SDL1.2-SIXEL WESNOTH](https://raw.githubusercontent.com/saitoha/libsixel/data/data/wesnoth.png)](http://youtu.be/aMUkN7TSct4)

You can run QEMU on SIXEL terminals.

  [![SDL1.2-SIXEL QEMU](https://raw.githubusercontent.com/saitoha/libsixel/data/data/qemu.png)](http://youtu.be/X6M5tgNjEuQ)

[SDL1.2-SIXEL](https://github.com/saitoha/SDL1.2-SIXEL) can collaborate with [XSDL-SIXEL](https://github.com/saitoha/xserver-xsdl-sixel).

  [![SDL1.2-SIXEL XSDL](https://raw.githubusercontent.com/saitoha/libsixel/data/data/xsdl.png)](http://youtu.be/UOTMGdUPYRo)

Furthermore some information of SIXEL-ready SDL applications are reported.

- [NetSurf](https://www.reddit.com/r/commandline/comments/4qyb90/netsurf_a_graphical_browser_on_xterm_using_sixel/)
  ([screenshot](http://imgur.com/a/Y6xH6))

- [Green PDF Viewer](https://www.reddit.com/r/commandline/comments/4oldf5/view_pdfs_in_terminal_requires_nixos_latest_git/)
  ([screenshot](https://m.reddit.com/r/commandline/comments/4oldf5/view_pdfs_in_terminal_requires_nixos_latest_git/))

- [DOOM](https://www.libsdl.org/projects/doom/)
  ([tweet](https://twitter.com/rattcv/status/775213402130046977))

- [firesdl](https://github.com/klange/firesdl)
  ([movie](https://www.youtube.com/watch?v=XubH2W39Xtc))


### Langage Bindings

#### [libsixel-python](https://pypi.python.org/pypi/libsixel-python/0.4.0)

  [converter.py](https://github.com/saitoha/libsixel/blob/master/examples/python/converter.py) example depends on it.

#### [mruby-sixel](https://github.com/kjunichi/mruby-sixel)

  Used by [mruby-webcam](https://github.com/kjunichi/mruby-webcam).

#### [libsixel-p6](https://github.com/timo/libsixel-p6)

  A [perl6](https://perl6.org/) bindings for libsixel

#### [sixel-sys](https://github.com/AdnoC/sixel-sys)

  [Rust](https://www.rust-lang.org/) FFI bindings for libsixel

#### [sixel-rs](https://github.com/AdnoC/sixel-rs)

  A safe [Rust](https://www.rust-lang.org/) wrapper for libsixel


### W3M integration

`img2sixel(1)` can be integrated with [Debian's w3m](https://tracker.debian.org/pkg/w3m)(maintained by [Tatsuya Kinoshita](https://github.com/tats)) that includes patches for *-sixel* option derived from [Arakiken's w3m fork(remoteimg branch)](https://bitbucket.org/arakiken/w3m/branch/remoteimg).

  ![w3m-sixel](https://raw.githubusercontent.com/saitoha/libsixel/data/data/w3m-sixel.png)


@uobikiemukot's [sdump](https://github.com/uobikiemukot/sdump) project selected another approach.
He wrote a w3mimgdisplay compatible program [yaimg-sixel](https://github.com/uobikiemukot/sdump/tree/master/yaimg-sixel).
It also works with [ranger](https://github.com/hut/ranger).

  ![w3m-yaimg-sixel](https://raw.githubusercontent.com/saitoha/libsixel/data/data/w3m-yaimg-sixel.jpg)


### X11 on SIXEL terminals

[Xsixel](https://github.com/saitoha/xserver-sixel) is a kdrive server implementation for SIXEL terminals.

  ![Xsixel](https://raw.githubusercontent.com/saitoha/libsixel/data/data/xsixel.png)

  ![Xsixel Blue Print](https://raw.githubusercontent.com/saitoha/libsixel/data/data/HowToBuildTerminalGUI.png)


### GNU Screen integration

[Arakiken's GNU Screen fork(sixel branch)](https://bitbucket.org/arakiken/screen/branch/sixel)
works with SIXEL-supported applications including above products.
This project is now in progress.
GUI flavored SIXEL applications will integrated with existing terminal applications on it.

  ![w3m-sixel-screen](https://raw.githubusercontent.com/saitoha/libsixel/data/data/w3m-sixel-screen.png)

  ![sixel-screen](https://raw.githubusercontent.com/saitoha/libsixel/data/data/arakikens-screen.jpg)

  ![xsixel-screen](https://raw.githubusercontent.com/saitoha/libsixel/data/data/xsixel-on-screen.png)

See also on [youtube](http://youtu.be/QQAqe32VkFg).

### Twitter client integration

Some NetBSD/OpenBSD users are doing amazing challenges.

#### [arakiken's mikutterm(mikutterm-sixel)](https://bitbucket.org/arakiken/mikutterm/branch/sixel)

  Now [mikutter](http://mikutter.hachune.net/) + [mikutterm](https://bitbucket.org/arakiken/mikutterm) works with libsixel inline-image extension.

  SIXEL works with old powerless machines such as

  [NetBSD/luna68k](http://wiki.netbsd.org/ports/luna68k/) (here is OMRON LUNA-II):

  ![mikutterm-netbsd-luna68k](https://raw.githubusercontent.com/saitoha/libsixel/data/data/mikutterm-netbsd-luna68k.jpg)

  [NetBSD/hp300](http://wiki.netbsd.org/ports/hp300/) (here is HP9000/425e):

  ![mikutterm-netbsd-hp9000](https://raw.githubusercontent.com/saitoha/libsixel/data/data/mikutterm-netbsd-hp9000.jpg)


#### [arakiken's tw(tw-sixel)](https://bitbucket.org/arakiken/tw/branch/sixel)

  [arakiken's tw(tw-sixel)](https://bitbucket.org/arakiken/tw/branch/sixel) works with libsixel inline-image extension.

  SIXEL works with old powerless machines such as [OpenBSD/luna88k](http://www.openbsd.org/luna88k.html) (here is OMRON LUNA-88K2 MC88100@33MHz):

  ![mikutterm-netbsd-hp9000](https://raw.githubusercontent.com/saitoha/libsixel/data/data/tw-openbsd-luna88k.jpg)


#### [sayaka-chan](https://github.com/isaki68k/sayaka/)

  [sayaka-chan](https://github.com/isaki68k/sayaka/)(PHP version) works with libsixel inline-image extension.

  SIXEL works with old powerless machines such as [NetBSD/x68k](http://wiki.netbsd.org/ports/x68k/) (here is SHARP X68030 with 060turbo):

  ![sayaka-chan](https://raw.githubusercontent.com/saitoha/libsixel/data/data/sayaka-netbsd-x68k.jpg)

  SIXEL works even in-kernel console. [@isaki68k](https://github.com/isaki68k) wrote
  [a patch for ite(4)](https://github.com/isaki68k/misc/blob/master/NetBSD/patch/x68k-ite-sixel.diff).

  ![ite(4)](https://raw.githubusercontent.com/saitoha/libsixel/data/data/ite.png)


### Other

#### [sixelSPAD](https://github.com/nilqed/sixelSPAD)

  [screenshot](https://nilqed.github.io/drawfe/)

  Includes 2 commands [fricas2sixel](https://github.com/nilqed/sixelSPAD/blob/master/bin/fricas2sixel)
  and [latex2sixel](https://github.com/nilqed/sixelSPAD/blob/master/bin/latex2sixel).

  ![latex2sixel](https://raw.githubusercontent.com/saitoha/libsixel/data/data/latex2sixel.jpg)

#### [Neofetch](https://github.com/dylanaraps/neofetch)

  Now `sixel` backend is implemented.
  See https://github.com/dylanaraps/neofetch/wiki/Image-Backends#sixel

  ![neofetch](https://raw.githubusercontent.com/saitoha/libsixel/data/data/neofetch.png)

#### [termplay](https://github.com/jD91mZM2/termplay)

  Depends on [sixel-sys](https://github.com/AdnoC/sixel-sys), `--converter=sixel` option is supported.

  [![termplay](https://github.com/saitoha/libsixel/blob/data/data/termplay.png)](https://youtu.be/sOHU1b-Ih90)

#### [sixelPreviewer](https://github.com/mikoto2000/sixelPreviewer)

  Simple scripts and development environment for realtime edit-previewing for dot, svg, markdown, ...etc.
  [![sixelPreviewer](https://raw.githubusercontent.com/saitoha/libsixel/data/data/sixelpreviewer.png)](https://youtu.be/iPzHWPGWHV4)

#### [sdump](https://github.com/uobikiemukot/sdump)

  A sixel image dumper, provides pdf previewer.

### [RetroArch](https://github.com/libretro/RetroArch)

  SIXEL video driver is provided if you build it with `--enable-sixel` option.
  ([screenshot](https://imgur.com/lf3bh2S))
  
  
## Highlighted features

### Improved compression

Former sixel encoders(such as [ppmtosixel](http://netpbm.sourceforge.net/doc/ppmtosixel.html)) are mainly designed for dot-matrix printers.
They minimize the amount of printer-head movement distance.
But nowadays this method did not represent the best performance for displaying sixel data on terminal emulators.
SIXEL data for terminals were found in 80's Usenet, but the technology of how to create them seems to be lost.
[kmiya's sixel](http://nanno.dip.jp/softlib/man/rlogin/sixel.tar.gz) introduces the encoding method which is re-designed
for terminal emulators to optimize the overhead of transporting SIXEL with keeping compatibility with former SIXEL terminal.
Now libsixel and ImageMagick's sixel coder follow it.

@arakiken, known as the maintainer of mlterm, describes about the way to generate high quality SIXEL, which is adopted by libsixel
([http://mlterm.sourceforge.net/libsixel.pdf](http://mlterm.sourceforge.net/libsixel.pdf), in Japanese).


### High quality quantization

`img2sixel(1)` supports color image quantization. It works well even if few number of colors are allowed.


## Terminal requirements

If you want to view a SIXEL image, you have to get a terminal which support sixel graphics.

Now SIXEL feature is supported by the following terminals.

- DEC VT series, VT240/VT241/VT330/VT340/VT282/VT284/VT286/VT382

- DECterm(dxterm)

- Kermit

- ZSTEM 340

- WRQ Reflection

- RLogin (Japanese terminal emulator)

  [http://nanno.dip.jp/softlib/man/rlogin/](http://nanno.dip.jp/softlib/man/rlogin/)

- mlterm

  [http://mlterm.sourceforge.net/](http://mlterm.sourceforge.net/)

  Works on each of X, WIN32 GDI, framebuffer, Android, Cocoa version.

- XTerm (compiled with `--enable-sixel-graphics` option)

  [http://invisible-island.net/xterm/](http://invisible-island.net/xterm/)

  You should launch xterm with "`-ti vt340`" option.
  The SIXEL palette is limited to a maximum of 16 colors.
  To avoid this limitation, Try

```sh
$ echo "XTerm*decTerminalID: vt340" >> $HOME/.Xresources
$ echo "XTerm*numColorRegisters: 256" >>  $HOME/.Xresources
$ xrdb $HOME/.Xresources
$ xterm
```

  or

```sh
$ xterm -xrm "XTerm*decTerminalID: vt340" -xrm "XTerm*numColorRegisters: 256"
```

- yaft

  [https://github.com/uobikiemukot/yaft](https://github.com/uobikiemukot/yaft)

- recterm (ttyrec to GIF converter)

  [https://github.com/uobikiemukot/recterm](https://github.com/uobikiemukot/recterm)

- seq2gif (ttyrec to GIF converter)

  [https://github.com/saitoha/seq2gif](https://github.com/saitoha/seq2gif)

- Mintty (>= 2.6.0)

  [https://mintty.github.io/](https://mintty.github.io/)

- cancer
  [https://github.com/meh/cancer/](https://github.com/meh/cancer)

- MacTerm
  [https://github.com/kmgrant/macterm](https://github.com/kmgrant/macterm)

- wezterm
  [https://github.com/wez/wezterm](https://github.com/wez/wezterm)

- aminal
  [https://github.com/liamg/aminal](https://github.com/liamg/aminal)

- iTerm2 (>= 3.0.0)
  [https://gitlab.com/gnachman/iterm2](https://gitlab.com/gnachman/iterm2)

- st-sixel
  [https://github.com/galatolofederico/st-sixel](https://github.com/galatolofederico/st-sixel)

- DomTerm
  [https://github.com/PerBothner/DomTerm](https://github.com/PerBothner/DomTerm)

- yaft-cocoa
  [https://github.com/uobikiemukot/yaft-cocoa](https://github.com/uobikiemukot/yaft-cocoa)

- toyterm
  [https://github.com/algon-320/toyterm](https://github.com/algon-320/toyterm)


## Install

### Using package managers

You can install libsixel via the following package systems.

- [FreeBSD ports](http://portsmon.freebsd.org/portoverview.py?category=graphics&portname=libsixel)
- [DPorts](https://github.com/DragonFlyBSD/DPorts/tree/master/graphics/libsixel)
- [pkgsrc](http://cvsweb.netbsd.org/bsdweb.cgi/pkgsrc/graphics/libsixel/)
- [Homebrew](https://formulae.brew.sh/formula/libsixel)
- [yacp](https://github.com/fd00/yacp/tree/master/libsixel)
- [Debian](https://packages.debian.org/search?searchon=names&keywords=libsixel)
- [AUR](https://aur.archlinux.org/packages/libsixel-git/)
- [Portage](http://packages.gentoo.org/package/media-libs/libsixel)
- [Ubuntu](https://launchpad.net/ubuntu/+source/libsixel)
- [NixOS](https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/libraries/libsixel/default.nix)
- [OpenBSD Ports](http://openports.se/graphics/libsixel)
- [Fedora Copr](https://copr.fedorainfracloud.org/coprs/saahriktu/libsixel/)
- [SlackBuilds](https://slackbuilds.org/repository/14.2/libraries/libsixel/)

### Build from source package

```
$ ./configure
$ make
# make install
```

#### Build with optional packages

You can configure with the following options

```
--with-libcurl            build with libcurl (default: auto)
--with-gd                 build with libgd (default: no)
--with-gdk-pixbuf2        build with gdk-pixbuf2 (default: no)
--with-jpeg               build with libjpeg (default: auto)
--with-png                build with libpng (default: auto)
--with-pkgconfigdir       specify pkgconfig dir (default is libdir/pkgconfig)
--with-bashcompletiondir  specify bashcompletion.d
--with-zshcompletiondir   specify zshcompletion.d
--enable-python           Python interface (default: yes)
--enable-debug            Use debug macro and specific CFLAGS
--enable-gcov             Use gcov
--enable-tests            Build tests
```

For more information, see "./configure --help".


##### Cross compiling with MinGW

You can build a windows binary in cross-build environment.

```
$ CC=i686-w64-mingw32-gcc cross_compile=yes ./configure --host=i686-w64-mingw32
$ make
```

## Usage of command line tools

### img2sixel

```
Usage: img2sixel [Options] imagefiles
       img2sixel [Options] < imagefile

Options:
-o, --outfile              specify output file name.
                           (default:stdout)
-7, --7bit-mode            generate a sixel image for 7bit
                           terminals or printers (default)
-8, --8bit-mode            generate a sixel image for 8bit
                           terminals or printers
-R, --gri-limit            limit arguments of DECGRI('!') to 255
-p COLORS, --colors=COLORS specify number of colors to reduce
                           the image to (default=256)
-m FILE, --mapfile=FILE    transform image colors to match this
                           set of colorsspecify map
-e, --monochrome           output monochrome sixel image
                           this option assumes the terminal
                           background color is black
-k, --insecure             allow to connect to SSL sites without
                           certs(enabled only when configured
                           with --with-libcurl)
-i, --invert               assume the terminal background color
                           is white, make sense only when -e
                           option is given
-I, --high-color           output 15bpp sixel image
-u, --use-macro            use DECDMAC and DEVINVM sequences to
                           optimize GIF animation rendering
-n MACRONO, --macro-number=MACRONO
                           specify an number argument for
                           DECDMAC and make terminal memorize
                           SIXEL image. No image is shown if
                           this option is specified
-C COMPLEXIONSCORE, --complexion-score=COMPLEXIONSCORE
                           specify an number argument for the
                           score of complexion correction.
                           COMPLEXIONSCORE must be 1 or more.
-g, --ignore-delay         render GIF animation without delay
-S, --static               render animated GIF as a static image
-d DIFFUSIONTYPE, --diffusion=DIFFUSIONTYPE
                           choose diffusion method which used
                           with -p option (color reduction)
                           DIFFUSIONTYPE is one of them:
                             auto     -> choose diffusion type
                                         automatically (default)
                             none     -> do not diffuse
                             fs       -> Floyd-Steinberg method
                             atkinson -> Bill Atkinson's method
                             jajuni   -> Jarvis, Judice & Ninke
                             stucki   -> Stucki's method
                             burkes   -> Burkes' method
                             a_dither -> positionally stable
                                         arithmetic dither
                             x_dither -> positionally stable
                                         arithmetic xor based dither
-f FINDTYPE, --find-largest=FINDTYPE
                           choose method for finding the largest
                           dimension of median cut boxes for
                           splitting, make sense only when -p
                           option (color reduction) is
                           specified
                           FINDTYPE is one of them:
                             auto -> choose finding method
                                     automatically (default)
                             norm -> simply comparing the
                                     range in RGB space
                             lum  -> transforming into
                                     luminosities before the
                                     comparison
-s SELECTTYPE, --select-color=SELECTTYPE
                           choose the method for selecting
                           representative color from each
                           median-cut box, make sense only
                           when -p option (color reduction) is
                           specified
                           SELECTTYPE is one of them:
                             auto      -> choose selecting
                                          method automatically
                                          (default)
                             center    -> choose the center of
                                          the box
                             average    -> calculate the color
                                          average into the box
                             histogram -> similar with average
                                          but considers color
                                          histogram
-c REGION, --crop=REGION   crop source image to fit the
                           specified geometry. REGION should
                           be formatted as '%dx%d+%d+%d'
-w WIDTH, --width=WIDTH    resize image to specified width
                           WIDTH is represented by the
                           following syntax
                             auto       -> preserving aspect
                                           ratio (default)
                             <number>%  -> scale width with
                                           given percentage
                             <number>   -> scale width with
                                           pixel counts
                             <number>px -> scale width with
                                           pixel counts
-h HEIGHT, --height=HEIGHT resize image to specified height
                           HEIGHT is represented by the
                           following syntax
                             auto       -> preserving aspect
                                           ratio (default)
                             <number>%  -> scale height with
                                           given percentage
                             <number>   -> scale height with
                                           pixel counts
                             <number>px -> scale height with
                                           pixel counts
-r RESAMPLINGTYPE, --resampling=RESAMPLINGTYPE
                           choose resampling filter used
                           with -w or -h option (scaling)
                           RESAMPLINGTYPE is one of them:
                             nearest  -> Nearest-Neighbor
                                         method
                             gaussian -> Gaussian filter
                             hanning  -> Hanning filter
                             hamming  -> Hamming filter
                             bilinear -> Bilinear filter
                                         (default)
                             welsh    -> Welsh filter
                             bicubic  -> Bicubic filter
                             lanczos2 -> Lanczos-2 filter
                             lanczos3 -> Lanczos-3 filter
                             lanczos4 -> Lanczos-4 filter
-q QUALITYMODE, --quality=QUALITYMODE
                           select quality of color
                           quanlization.
                             auto -> decide quality mode
                                     automatically (default)
                             low  -> low quality and high
                                     speed mode
                             high -> high quality and low
                                     speed mode
                             full -> full quality and careful
                                     speed mode
-l LOOPMODE, --loop-control=LOOPMODE
                           select loop control mode for GIF
                           animation.
                             auto    -> honor the setting of
                                        GIF header (default)
                             force   -> always enable loop
                             disable -> always disable loop
-t PALETTETYPE, --palette-type=PALETTETYPE
                           select palette color space type
                             auto -> choose palette type
                                     automatically (default)
                             hls  -> use HLS color space
                             rgb  -> use RGB color space
-b BUILTINPALETTE, --builtin-palette=BUILTINPALETTE
                           select built-in palette type
                             xterm16    -> X default 16 color map
                             xterm256   -> X default 256 color map
                             vt340mono  -> VT340 monochrome map
                             vt340color -> VT340 color map
                             gray1      -> 1bit grayscale map
                             gray2      -> 2bit grayscale map
                             gray4      -> 4bit grayscale map
                             gray8      -> 8bit grayscale map
-E ENCODEPOLICY, --encode-policy=ENCODEPOLICY
                           select encoding policy
                             auto -> choose encoding policy
                                     automatically (default)
                             fast -> encode as fast as possible
                             size -> encode to as small sixel
                                     sequence as possible
-B BGCOLOR, --bgcolor=BGCOLOR
                           specify background color
                           BGCOLOR is represented by the
                           following syntax
                             #rgb
                             #rrggbb
                             #rrrgggbbb
                             #rrrrggggbbbb
                             rgb:r/g/b
                             rgb:rr/gg/bb
                             rgb:rrr/ggg/bbb
                             rgb:rrrr/gggg/bbbb
-P, --penetrate            penetrate GNU Screen using DCS
                           pass-through sequence
-D, --pipe-mode            [[deprecated]] read source images from
                           stdin continuously
-v, --verbose              show debugging info
-V, --version              show version and license info
-H, --help                 show this help

Environment variables:
SIXEL_BGCOLOR              specify background color.
                           overrided by -B(--bgcolor) option.
                           represented by the following
                           syntax:
                             #rgb
                             #rrggbb
                             #rrrgggbbb
                             #rrrrggggbbbb
                             rgb:r/g/b
                             rgb:rr/gg/bb
                             rgb:rrr/ggg/bbb
                             rgb:rrrr/gggg/bbbb

```

Convert a jpeg image file into a sixel file

```
$ img2sixel < images/egret.jpg > egret.sixel
```

Reduce colors to 16:

```
$ img2sixel -p 16 < images/egret.jpg > egret.sixel
```

Reduce colors with fixed palette:

```
$ img2sixel -m images/map16.png < images/egret.jpg > egret.sixel
```

### sixel2png

```
Usage: sixel2png -i input.sixel -o output.png
       sixel2png < input.sixel > output.png

Options:
-i, --input     specify input file
-o, --output    specify output file
-V, --version   show version and license information
-H, --help      show this help
```

Convert a sixel file into a png image file

```
$ sixel2png < egret.sixel > egret.png
```

## The high-level conversion API

The high-livel API provides File-to-File conversion features.


### Encoder

The sixel encoder object and related functions provides almost same features as `img2sixel`.

```C
/* create encoder object */
SIXELAPI SIXELSTATUS
sixel_encoder_new(
    sixel_encoder_t     /* out */ **ppencoder, /* encoder object to be created */
    sixel_allocator_t   /* in */  *allocator); /* allocator, null if you use
                                                  default allocator */

/* increase reference count of encoder object (thread-unsafe) */
SIXELAPI void
sixel_encoder_ref(sixel_encoder_t /* in */ *encoder);

/* decrease reference count of encoder object (thread-unsafe) */
SIXELAPI void
sixel_encoder_unref(sixel_encoder_t /* in */ *encoder);

/* set cancel state flag to encoder object */
SIXELAPI SIXELSTATUS
sixel_encoder_set_cancel_flag(
    sixel_encoder_t /* in */ *encoder,
    int             /* in */ *cancel_flag);

/* set an option flag to encoder object */
SIXELAPI SIXELSTATUS
sixel_encoder_setopt(
    sixel_encoder_t /* in */ *encoder,
    int             /* in */ arg,
    char const      /* in */ *optarg);

/* load source data from specified file and encode it to SIXEL format */
SIXELAPI SIXELSTATUS
sixel_encoder_encode(
    sixel_encoder_t /* in */ *encoder,
    char const      /* in */ *filename);
```

### Decoder

The sixel decoder object and related functions provides almost same features as `sixel2png`.

```C
/* create decoder object */
SIXELAPI SIXELSTATUS
sixel_decoder_new(
    sixel_decoder_t    /* out */ **ppdecoder,  /* decoder object to be created */
    sixel_allocator_t  /* in */  *allocator);  /* allocator, null if you use
                                                  default allocator */

/* increase reference count of decoder object (thread-unsafe) */
SIXELAPI void
sixel_decoder_ref(sixel_decoder_t *decoder);

/* decrease reference count of decoder object (thread-unsafe) */
SIXELAPI void
sixel_decoder_unref(sixel_decoder_t *decoder);

/* set an option flag to decoder object */
SIXELAPI SIXELSTATUS
sixel_decoder_setopt(
    sixel_decoder_t /* in */ *decoder,  /* decoder object */
    int             /* in */ arg,       /* one of SIXEL_OPTFLAG_*** */
    char const      /* in */ *optarg);  /* null or an argument of optflag */

/* load source data from stdin or the file specified with
   SIXEL_OPTFLAG_INPUT flag, and decode it */
SIXELAPI SIXELSTATUS
sixel_decoder_decode(
    sixel_decoder_t /* in */ *decoder);
```


## The low-level conversion API

The low-livel API provides Bytes-to-Bytes conversion features.

The Whole API is described [here](https://github.com/saitoha/libsixel/blob/master/include/sixel.h.in).

### Examples

#### OpenGL

[OpenGL example](https://github.com/saitoha/libsixel/blob/master/examples/opengl/)
suggests how to port your OpenGL application to SIXEL terminal.

  ![opengl example](https://raw.githubusercontent.com/saitoha/libsixel/data/data/example_opengl.gif)


#### Drawing

[Drawing example](https://github.com/saitoha/libsixel/blob/master/examples/drawing/)
suggests how to implement the interaction among SIXEL terminals and pointer devices.

  [![drawing](https://raw.githubusercontent.com/saitoha/libsixel/data/data/drawing.png)](https://youtu.be/2-2FnoZp4Z0)


#### Python

[Python example](https://github.com/saitoha/libsixel/blob/master/examples/python/)
suggests how to convert PIL images into SIXEL using libsixel python interface.


### Bitmap to SIXEL

`sixel_encode` function converts bitmap array into SIXEL format.

```C
/* convert pixels into sixel format and write it to output context */
SIXELAPI SIXELSTATUS
sixel_encode(
    unsigned char  /* in */ *pixels,     /* pixel bytes */
    int            /* in */  width,      /* image width */
    int            /* in */  height,     /* image height */
    int            /* in */  depth,      /* color depth: now unused */
    sixel_dither_t /* in */ *dither,     /* dither context */
    sixel_output_t /* in */ *context);   /* output context */
```
To use this function, you have to initialize two objects,

- `sixel_dither_t` (dithering context object)
- `sixel_output_t` (output context object)

#### Dithering context

Here is a part of APIs for dithering context manipulation.

```C
/* create dither context object */
SIXELAPI SIXELSTATUS
sixel_dither_new(
    sixel_dither_t      /* out */   **ppdither,  /* dither object to be created */
    int                 /* in */    ncolors,     /* required colors */
    sixel_allocator_t   /* in */    *allocator); /* allocator, null if you use
                                                    default allocator */

/* get built-in dither context object */
SIXELAPI sixel_dither_t *
sixel_dither_get(int builtin_dither); /* ID of built-in dither object */

/* destroy dither context object */
SIXELAPI void
sixel_dither_destroy(sixel_dither_t *dither); /* dither context object */

/* increase reference count of dither context object (thread-unsafe) */
SIXELAPI void
sixel_dither_ref(sixel_dither_t *dither); /* dither context object */

/* decrease reference count of dither context object (thread-unsafe) */
SIXELAPI void
sixel_dither_unref(sixel_dither_t *dither); /* dither context object */

/* initialize internal palette from specified pixel buffer */
SIXELAPI SIXELSTATUS
sixel_dither_initialize(
    sixel_dither_t *dither,          /* dither context object */
    unsigned char /* in */ *data,    /* sample image */
    int /* in */ width,              /* image width */
    int /* in */ height,             /* image height */
    int /* in */ pixelformat,        /* one of enum pixelFormat */
    int /* in */ method_for_largest, /* method for finding the largest dimension */
    int /* in */ method_for_rep,     /* method for choosing a color from the box */
    int /* in */ quality_mode);      /* quality of histogram processing */

/* set diffusion type, choose from enum methodForDiffuse */
SIXELAPI void
sixel_dither_set_diffusion_type(
    sixel_dither_t /* in */ *dither,   /* dither context object */
    int /* in */ method_for_diffuse);  /* one of enum methodForDiffuse */

/* get number of palette colors */
SIXELAPI int
sixel_dither_get_num_of_palette_colors(
    sixel_dither_t /* in */ *dither);  /* dither context object */

/* get number of histogram colors */
SIXELAPI int
sixel_dither_get_num_of_histogram_colors(
    sixel_dither_t /* in */ *dither);  /* dither context object */

/* get palette */
SIXELAPI unsigned char *
sixel_dither_get_palette(
    sixel_dither_t /* in */ *dither);  /* dither context object */

/* set palette */
SIXELAPI void
sixel_dither_set_palette(
    sixel_dither_t /* in */ *dither,   /* dither context object */
    unsigned char  /* in */ *palette);

SIXELAPI void
sixel_dither_set_complexion_score(
    sixel_dither_t /* in */ *dither,   /* dither context object */
    int            /* in */ score);    /* complexion score (>= 1) */

SIXELAPI void
sixel_dither_set_body_only(
    sixel_dither_t /* in */ *dither,   /* dither context object */
    int            /* in */ bodyonly); /* 0: output palette section(default)
                                          1: do not output palette section */
SIXELAPI void
sixel_dither_set_optimize_palette(
    sixel_dither_t /* in */ *dither,   /* dither context object */
    int            /* in */ do_opt);   /* 0: optimize palette size
                                          1: don't optimize palette size */
/* set pixelformat */
SIXELAPI void
sixel_dither_set_pixelformat(
    sixel_dither_t /* in */ *dither,      /* dither context object */
    int            /* in */ pixelformat); /* one of enum pixelFormat */

/* set transparent */
SIXELAPI void
sixel_dither_set_transparent(
    sixel_dither_t /* in */ *dither,      /* dither context object */
    int            /* in */ transparent); /* transparent color index */
```

#### Output context

Here is a part of APIs for output context manipulation.

```C
/* create output context object */
SIXELAPI SIXELSTATUS
sixel_output_new(
    sixel_output_t          /* out */ **output,     /* output object to be created */
    sixel_write_function    /* in */  fn_write,     /* callback for output sixel */
    void                    /* in */ *priv,         /* private data given as
                                                       3rd argument of fn_write */
    sixel_allocator_t       /* in */  *allocator);  /* allocator, null if you use
                                                       default allocator */

/* destroy output context object */
SIXELAPI void
sixel_output_destroy(sixel_output_t /* in */ *output); /* output context */

/* increase reference count of output context object (thread-unsafe) */
SIXELAPI void
sixel_output_ref(sixel_output_t /* in */ *output);     /* output context */

/* decrease reference count of output context object (thread-unsafe) */
SIXELAPI void
sixel_output_unref(sixel_output_t /* in */ *output);   /* output context */

/* set 8bit output mode which indicates whether it uses C1 control characters */
SIXELAPI int
sixel_output_get_8bit_availability(
    sixel_output_t /* in */ *output);   /* output context */

/* get 8bit output mode state */
SIXELAPI void
sixel_output_set_8bit_availability(
    sixel_output_t /* in */ *output,       /* output context */
    int            /* in */ availability); /* 0: do not use 8bit characters
                                              1: use 8bit characters */

/* set GNU Screen penetration feature enable or disable */
SIXELAPI void
sixel_output_set_penetrate_multiplexer(
    sixel_output_t /* in */ *output,    /* output context */
    int            /* in */ penetrate); /* 0: penetrate GNU Screen
                                           1: do not penetrate GNU Screen */

/* set whether we skip DCS envelope */
SIXELAPI void
sixel_output_set_skip_dcs_envelope(
    sixel_output_t /* in */ *output,   /* output context */
    int            /* in */ skip);     /* 0: output DCS envelope
                                          1: do not output DCS envelope */

SIXELAPI void
sixel_output_set_palette_type(
    sixel_output_t /* in */ *output,      /* output context */
    int            /* in */ palettetype); /* PALETTETYPE_RGB: RGB palette
                                             PALETTETYPE_HLS: HLS palette */

SIXELAPI void
sixel_output_set_encode_policy(
    sixel_output_t /* in */ *output,    /* output context */
    int            /* in */ encode_policy);
```

### SIXEL to indexed bitmap

`sixel_decode` function converts SIXEL into indexed bitmap bytes with its palette.

```
/* convert sixel data into indexed pixel bytes and palette data */
SIXELAPI SIXELSTATUS
sixel_decode_raw(
    unsigned char       /* in */  *p,           /* sixel bytes */
    int                 /* in */  len,          /* size of sixel bytes */
    unsigned char       /* out */ **pixels,     /* decoded pixels */
    int                 /* out */ *pwidth,      /* image width */
    int                 /* out */ *pheight,     /* image height */
    unsigned char       /* out */ **palette,    /* ARGB palette */
    int                 /* out */ *ncolors,     /* palette size (<= 256) */
    sixel_allocator_t   /* in */  *allocator);  /* allocator object */
```

## Perl interface

This package includes a perl module `Image::Sixel`.

### Build and install Perl interface

```
$ cd perl
$ perl Build.PL
$ ./Build test
$ ./Build install
```

## Python interface

This package includes a Python module `libsixel`.

### Build and install Python interface

#### Install into the python prefixed with '/usr/local'

```
$ git clone https://github.com/saitoha/libsixel.git
$ cd libsixel
$ git checkout develop  # now available only develop branch
$ ./configure --enable-python --prefix=/usr/local
$ make install
```

#### Install into only current active python

```
$ git clone https://github.com/saitoha/libsixel.git
$ cd libsixel
$ git checkout develop  # now available only develop branch
$ ./configure --disable-python
$ make install  # install libsixel
$ cd python
$ python setup.py install  # install python module
```

or

```
$ easy_install libsixel-python
```

## PHP interface

This package includes a PHP module `sixel`.

### Build and install PHP interface

```
$ cd php/sixel
$ phpize
$ ./configure
$ make install
```

## Ruby interface

### Build and install Ruby interface

```
$ gem install libsixel-ruby
```

or

```
$ git submodule update --init
$ rake compile
$ rake build install
```


## Support

This software is provided "as is" without express or implied warranty.
The main support channel for this software is the github issue tracker:

  [https://github.com/saitoha/libsixel/issues](https://github.com/saitoha/libsixel/issues)


Please post your issue if you have any problems, questions or suggestions.


## License

The MIT License (MIT)

> Copyright (c) 2014 Hayaki Saito
>
> Permission is hereby granted, free of charge, to any person obtaining a copy of
> this software and associated documentation files (the "Software"), to deal in
> the Software without restriction, including without limitation the rights to
> use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
> the Software, and to permit persons to whom the Software is furnished to do so,
> subject to the following conditions:
>
> The above copyright notice and this permission notice shall be included in all
> copies or substantial portions of the Software.
>
> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
> FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
> COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
> IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
> CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

## Contributers and Reviewers

- [@arakiken](https://github.com/arakiken/)
- [@elfring](https://github.com/elfring/)
- [@fd00](https://github.com/fd00/)
- [@hattya](https://github.com/hattya/)
- [@isaki68k](https://github.com/isaki68k/)
- [@knok](https://github.com/knok/)
- [@mattn](https://github.com/mattn/)
- [@msmhrt](https://github.com/msmhrt/)
- [@obache](https://github.com/obache/)
- [@tsutsui](https://github.com/tsutsui/)
- [@ttdoda](https://github.com/ttdoda/)
- [@turenar](https://github.com/turenar/)
- [@uobikiemukot](https://github.com/uobikiemukot/)
- [@vrtsds](https://github.com/vrtsds/)
- [@waywardmonkeys](https://github.com/waywardmonkeys/)
- [@yoshikaw](https://github.com/yoshikaw/)
- [@turenar](https://github.com/turenar/)
- [@mame](https://github.com/mame/)
- [@hodefoting](https://github.com/hodefoting/)
- [@fCorleone](@https://github.com/fCorleone)
- [@fgeek](https://github.com/fgeek/)
- [@HongxuChen](https://github.com/HongxuChen/)
- [@YourButterfly](https://github.com/YourButterfly/)
- [@nluedtke](https://github.com/nluedtke/)
- [@cool-tomato](https://github.com/cool-tomato/)

## Contributing

1. Fork it ( https://github.com/saitoha/libsixel/fork/ )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request


## Acknowledgment

This software derives from the following implementations.

### sixel 2014-3-2

src/tosixel.c, src/fromsixel.c, and some part of converters/loader.c are
derived from kmiya's "*sixel*" original version (2014-3-2)

  Package: http://nanno.dip.jp/softlib/man/rlogin/sixel.tar.gz

  Unofficial repo: https://github.com/saitoha/sixel

This work is written by kmiya@ culti. He distributes it under very permissive license.

The original license text(in Japanese) is:

```
このプログラム及びソースコードの使用について個人・商用を問わず

ご自由に使用していただいで結構です。

また、配布・転載・紹介もご連絡の必要もありません。

ソースの改変による配布も自由ですが、どのバージョンの改変かを

明記されることを希望します。

バージョン情報が無い場合は、配布物の年月日を明記されることを

希望します。

                  2014/10/05  kmiya
```

The unofficial translation:

```
Anyone is free to use this program for any purpose,
commercial or non-commercial, without any restriction.

Anyone is free to distribute, copy, publish, or
advertise this software, without any contact.

Anyone is free to distribute with modification of the
source code, but I "hope" that its based version or
date will be written clearly.

                                    2014/10/05 kmiya
```

kmiya also said this is compatible with MIT/BSD/GPL.


### stbi-2.12

This software includes `stb-image-v2.12` (stb_image.h),
public domain JPEG/PNG reader.

https://github.com/nothings/stb

> LICENSE
>
> This software is in the public domain. Where that dedication is not
> recognized, you are granted a perpetual, irrevocable license to copy,
> distribute, and modify this file as you see fit.


### stbiw-1.02
This software includes `stb-image-write-v1.02` (stb_image_write.h),
public domain PNG/BMP/TGA writer.

https://github.com/nothings/stb

> LICENSE
>
> This software is in the public domain. Where that dedication is not
> recognized, you are granted a perpetual, irrevocable license to copy,
> distribute, and modify this file as you see fit.


### pnmquant.c (netpbm library)

The implementation of median cut algorithm for color quantization in quant.c
is imported from `pnmcolormap` included in `netpbm library`.

http://netpbm.sourceforge.net/

`pnmcolormap` was derived from `ppmquant`, originally written by Jef Poskanzer.

> Copyright (C) 1989, 1991 by Jef Poskanzer.
> Copyright (C) 2001 by Bryan Henderson.
>
> Permission to use, copy, modify, and distribute this software and its
> documentation for any purpose and without fee is hereby granted, provided
> that the above copyright notice appear in all copies and that both that
> copyright notice and this permission notice appear in supporting
> documentation.  This software is provided "as is" without express or
> implied warranty.


### loader.h (@uobikiemukot's sdump)

Some parts of converters/loader.c are imported from @uobikiemukot's
[sdump](https://github.com/uobikiemukot/sdump) project

> The MIT License (MIT)
>
> Copyright (c) 2014 haru <uobikiemukot at gmail dot com>
>
> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
>
> The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


### ax_gcc_var_attribute / ax_gcc_func_attribute

These are useful m4 macros for detecting some GCC attributes / built-in functions.

http://www.gnu.org/software/autoconf-archive/ax_gcc_var_attribute.html
http://www.gnu.org/software/autoconf-archive/ax_gcc_func_attribute.html
http://www.gnu.org/software/autoconf-archive/ax_gcc_builtin.html

> Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com>
>
> Copying and distribution of this file, with or without modification, are
> permitted in any medium without royalty provided the copyright notice
> and this notice are preserved.  This file is offered as-is, without any
> warranty.


### graphics.c (from Xterm pl#310)

The helper function `hls2rgb` in `src/fromsixel.c` is imported from
`graphics.c` in [Xterm pl#310](http://invisible-island.net/xterm/),
originally written by Ross Combs.

> Copyright 2013,2014 by Ross Combs
>
>                         All Rights Reserved
>
> Permission is hereby granted, free of charge, to any person obtaining a
> copy of this software and associated documentation files (the
> "Software"), to deal in the Software without restriction, including
> without limitation the rights to use, copy, modify, merge, publish,
> distribute, sublicense, and/or sell copies of the Software, and to
> permit persons to whom the Software is furnished to do so, subject to
> the following conditions:
>
> The above copyright notice and this permission notice shall be included
> in all copies or substantial portions of the Software.
>
> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
> OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
> IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
> CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
> TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
> SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
>
> Except as contained in this notice, the name(s) of the above copyright
> holders shall not be used in advertising or otherwise to promote the
> sale, use or other dealings in this Software without prior written
> authorization.


### test images

#### http://public-domain-photos.com/

The following test images in "image/" directory came from PUBLIC-DOMAIN-PHOTOS.com.

- images/egret.jpg

    author: Jon Sullivan
    url: http://public-domain-photos.com/animals/egret-4.htm

- images/snake.jpg

    author: Jon Sullivan
    url: http://public-domain-photos.com/animals/snake-4.htm

These are in the [public domain](http://creativecommons.org/licenses/publicdomain/).


#### vimperator3.png (mascot of vimperator)

images/vimperator3.png is in the public domain.

    author: @k_wizard
    url: http://quadrantem.com/~k_wizard/vimprtan/


#### PngSuite

Images under the directory images/pngsuite/ are imported from
[PngSuite](http://www.schaik.com/pngsuite/) created by Willem van Schaik.

> Permission to use, copy, modify and distribute these images for any
> purpose and without fee is hereby granted.
>
>
>(c) Willem van Schaik, 1996, 2011


## References

### ImageMagick

We are greatly inspired by the quality of ImageMagick and added some resampling filters to
`img2sixel` in reference to the line-up of filters of MagickCore's resize.c.

    http://www.imagemagick.org/api/MagickCore/resize_8c_source.html


## Similar software

- [netpbm](http://netpbm.sourceforge.net/)

  You can get SIXEL graphics using [ppmtosixel](http://netpbm.sourceforge.net/doc/ppmtosixel.html)
  or [pbmtoln03](http://netpbm.sourceforge.net/doc/ppmtosixel.html).


- [kmiya's sixel](http://nanno.dip.jp/softlib/man/rlogin/sixel.tar.gz)

  libgd based SIXEL converter


- [PySixel](https://pypi.python.org/pypi/PySixel)

  Python implementation of SIXEL converter


- [ImageMagick](http://www.imagemagick.org/)

  Now SIXEL coder is available in svn trunk and V6 branch.


- [monosixel in arakiken's tw](https://bitbucket.org/arakiken/tw/branch/sixel)

  A monochrome SIXEL converter


- [sixelv in sayaka-chan Vala version](https://github.com/isaki68k/sayaka/blob/master/vala/sixelv.vala)

  sayaka-chan(Vala version) also includes SIXEL converter.


- [rust-sixel](https://github.com/meh/rust-sixel)

  A SIXEL encoder written in rust.


- [forth-sixel](https://hub.darcs.net/pointfree/forth-sixel)

  A SIXEL encoder written in forth.


- [ff2sixel](https://github.com/labdsf/ff2sixel)

  An utility to convert farbfeld images to Sixels.


- [tv](https://github.com/hodefoting/tv)

  terminal/commandline image viewer


- [xpr(x11-apps)](ftp://ftp.x.org/pub/unsupported/programs/xpr/)

  xpr(1) can convert a xwd(X window dump) format image into a sixel
  image with '-device ln03' or '-device la100' option.
  But now it is not maintained. It looks broken.


## Other software supporting SIXEL

- [GNUPLOT](http://www.gnuplot.info/)

  Recent version of GNUPLOT supports new terminal driver "sixeltek(sixel)" / "sixelgd".

  ![GNUPLOT](https://raw.githubusercontent.com/saitoha/libsixel/data/data/gnuplot.png)


- [ghostscript](http://www.ghostscript.com/)

  You can emit SIXEL images with LN03 / LN50 / LA75 driver.

  example:

  ```
    $ gs -q -r100x -dBATCH -dNOPAUSE -sDEVICE=ln03 -sOutputFile=- tiger.eps
  ```

  ![GhostScript](https://raw.githubusercontent.com/saitoha/libsixel/data/data/gs.png)


- [ImageMagick](http://www.imagemagick.org/)

  Recent version of ImageMagick provides SIXEL coder. It's also available over commandline tools.

  ![ImageMagick](https://raw.githubusercontent.com/saitoha/libsixel/data/data/imagemagick.png)


- [lsix](https://github.com/hackerb9/lsix)

  Like "ls", but for images. Shows thumbnails in terminal using sixel graphics.
  ![lsix](https://raw.githubusercontent.com/saitoha/libsixel/data/data/lsix.jpg)


- [sixeldraw](https://github.com/aiju/sixeldraw)

  Sixel support for p9p devdraw

  cmapcube on xterm with DEVDRAW=sixeldraw
  [![sixeldraw2](https://raw.githubusercontent.com/saitoha/libsixel/data/data/sixeldraw2.png)](https://youtu.be/EOvSrt7Yi00)

  acme on xterm with DEVDRAW=sixeldraw SNARF=1
  [![sixeldraw1](https://raw.githubusercontent.com/saitoha/libsixel/data/data/sixeldraw1.png)](https://youtu.be/eGjSEjxiDjE)


- [ZX81 Emulator](http://rullf2.xs4all.nl/sg/zx81ce.html)

  A ZX81 emulator producing Sixel Image Files

  ![ZX81](https://raw.githubusercontent.com/saitoha/libsixel/data/data/zx81.png)


- [qrc](https://github.com/fumiyas/qrc)

  QR code generator for terminals (ASCII Art, Sixel)

  ![qrc](https://github.com/fumiyas/qrc/blob/master/qrc-demo.png)


- [go-sixel](https://github.com/mattn/go-sixel)

  SIXEL encoder/decoder and command line tools writtern in golang.

  ![go-sixel](https://raw.githubusercontent.com/saitoha/libsixel/data/data/go-sixel.png)


- [hiptext](https://github.com/jart/hiptext)

  SIXEL format is supported by -sixel2, -sixel16 or -sixel256 option.

  ![hiptext](https://camo.githubusercontent.com/fc973ffb20a7ff85969df03fd579da2845e62e68/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f313136323733392f323233393832362f39303361653765382d396335622d313165332d383462362d3539626261346661336430342e706e67)


- [sixelslide](https://github.com/syuu1228/sixelslide)

  Freestanding slideviewer using sixel graphics.
  Currently runs on QEMU(i386), without any filesystem or network.

  ![Animation](https://raw.githubusercontent.com/saitoha/libsixel/data/data/sixelslide.png)

  cf. http://www.slideshare.net/syuu1228/presentation-on-your-terminal


- [GraphicConverter](https://itunes.apple.com/jp/app/graphicconverter-9/id736099092?mt=12)

  It can import SIXEL images.

  ![GraphicConverter](https://raw.githubusercontent.com/saitoha/libsixel/data/data/graphicconverter.png)


- [SIXEL image viewer](http://rullf2.xs4all.nl/sg/sg.html)

  This web page can decode SIXEL images (written in javascript).

  ![SIXEL image viewer ](https://raw.githubusercontent.com/saitoha/libsixel/data/data/js-sixel.png)


- [mandel4](http://kildall.apana.org.au/~cjb/mandel5.c)

  A mandelbrot program for (colour) sixel-supporting terminals, written by Chris Baird

  ![mandel4](https://raw.githubusercontent.com/saitoha/libsixel/data/data/mandel.png)


- [SixelGraphics.jl(written in Julia)](https://github.com/olofsen/SixelGraphics.jl)

  A module for Julia implementing simple Sixel graphics.

  ![SixelGraphics.jl](https://raw.githubusercontent.com/saitoha/libsixel/data/data/julia.png)


- ![PGPLOT](http://www.astro.caltech.edu/~tjp/pgplot/)


- [SIXEL to PostScript converter](http://t.co/zTC7LhRbBc)


- [sixelplot](https://github.com/kktk-KO/sixelplot)

  thin-wrapper for pysixel and matplotlib


- [ame.sh](https://github.com/hamano/ame.sh)

- [matplotlib-sixel](https://github.com/koppa/matplotlib-sixel)

- [gr framework](http://gr-framework.org/)

- [o2sh/onefetch](https://github.com/o2sh/onefetch)

- [lesnitsky/sixel-decoder](https://github.com/lesnitsky/sixel-decoder)

- [unhappychoice/irasutoya-cli](https://github.com/unhappychoice/irasutoya-cli)

- [ushitora-anqou/tinysixel](https://github.com/ushitora-anqou/tinysixel)

- [adzierzanowski/timg](https://github.com/adzierzanowski/timg)

- [SAT1226/Minase](https://github.com/SAT1226/Minase)

- [danr/neptyne](https://github.com/danr/neptyne)

- [klamonte/jexer](https://github.com/klamonte/jexer)

- [ar90n/teimpy](https://github.com/ar90n/teimpy)

- [fastai](https://github.com/fastai/fastai)

- [coderobe/crixel](https://github.com/coderobe/crixel)

- [itchyny/mkrg](https://github.com/itchyny/mkrg)

- [tshort/SixelTerm.jl](https://github.com/tshort/SixelTerm.jl)

- [dsanson/termpdf](https://github.com/dsanson/termpdf)

- [otiai10/amesh](https://github.com/otiai10/amesh)

- [hpjansson/chafa](https://github.com/hpjansson/chafa)

- [m-j-w/TerminalGraphics.jl](https://github.com/m-j-w/TerminalGraphics.jl)

- [MIC-DKFZ/niicat](https://github.com/MIC-DKFZ/niicat)

- [libretro/RetroArch](https://github.com/libretro/RetroArch)

- [jerch/node-sixel](https://github.com/jerch/node-sixel)

- [nikiroo/fanfix](https://github.com/nikiroo/fanfix)

- [mattn/longcat](https://github.com/mattn/longcat)

- [ismail-yilmaz/upp-components/CtrlLib/Terminal/](https://github.com/ismail-yilmaz/upp-components/tree/master/CtrlLib/Terminal)

- [schrmh/pdfgrepSIXEL](schrmh/pdfgrepSIXEL)

- [ar90n/teimpy](https://github.com/ar90n/teimpy)

- [vifm/vifm](https://github.com/vifm/vifm)

- [ktye/iv](https://github.com/ktye/iv/commit/815e06ed776dde3deca0fdba35da5f0b431a69bf)

- [Delta/longdog](https://github.com/0Delta/longdog)