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/*====================================================================*
- Copyright (C) 2001 Leptonica. All rights reserved.
- This software is distributed in the hope that it will be
- useful, but with NO WARRANTY OF ANY KIND.
- No author or distributor accepts responsibility to anyone for the
- consequences of using this software, or for whether it serves any
- particular purpose or works at all, unless he or she says so in
- writing. Everyone is granted permission to copy, modify and
- redistribute this source code, for commercial or non-commercial
- purposes, with the following restrictions: (1) the origin of this
- source code must not be misrepresented; (2) modified versions must
- be plainly marked as such; and (3) this notice may not be removed
- or altered from any source or modified source distribution.
*====================================================================*/
/*
* pagesegtest2.c
*
* This gives examples of the use of binary morphology for
* some simple and fast document segmentation operations.
*
* The operations are carried out at 2x reduction.
* For images scanned at 300 ppi, this is typically
* high enough resolution for accurate results.
*/
#include <stdio.h>
#include <stdlib.h>
#include "allheaders.h"
/* Control the output */
#define HT_DISP 1
#define WS_MASK 1
#define TEXT_DISP 1
#define BLOCK_DISP 1
#define DFLAG 0
main(int argc,
char **argv)
{
l_int32 index, zero;
char *filein;
BOXA *boxatm, *boxahm;
PIX *pixs; /* input image, say, at 300 ppi */
PIX *pixr; /* image reduced to 150 ppi */
PIX *pixhs; /* image of halftone seed, 150 ppi */
PIX *pixm; /* image of mask of components, 150 ppi */
PIX *pixhm1; /* image of halftone mask, 150 ppi */
PIX *pixhm2; /* image of halftone mask, 300 ppi */
PIX *pixht; /* image of halftone components, 150 ppi */
PIX *pixnht; /* image without halftone components, 150 ppi */
PIX *pixi; /* inverted image, 150 ppi */
PIX *pixvws; /* image of vertical whitespace, 150 ppi */
PIX *pixtm1; /* image of closed textlines, 150 ppi */
PIX *pixtm2; /* image of refined text line mask, 150 ppi */
PIX *pixtm3; /* image of refined text line mask, 300 ppi */
PIX *pixtb1; /* image of text block mask, 150 ppi */
PIX *pixtb2; /* image of text block mask, 300 ppi */
PIX *pixnon; /* image of non-text or halftone, 150 ppi */
PIX *pixt1, *pixt2, *pixt3, *pixt4, *pixt5;
PIXA *pixa;
PIXCMAP *cmap;
PTAA *ptaa;
static char mainName[] = "pagesegtest2";
if (argc != 2)
exit(ERROR_INT(" Syntax: pagesegtest2 filein", mainName, 1));
filein = argv[1];
if ((pixs = pixRead(filein)) == NULL)
exit(ERROR_INT("pix not made", mainName, 1));
/* Reduce to 150 ppi */
pixt1 = pixScaleToGray2(pixs);
pixDisplayWrite(pixt1, L_MAX(WS_MASK, L_MAX(HT_DISP, BLOCK_DISP)));
pixWrite("junk_orig.gray.150.png", pixt1, IFF_PNG);
pixDestroy(&pixt1);
pixr = pixReduceRankBinaryCascade(pixs, 1, 0, 0, 0);
/* Get seed for halftone parts */
pixt1 = pixReduceRankBinaryCascade(pixr, 4, 4, 3, 0);
pixt2 = pixOpenBrick(NULL, pixt1, 5, 5);
pixhs = pixExpandBinaryPower2(pixt2, 8);
pixDisplayWrite(pixhs, HT_DISP);
pixWrite("junk_htseed.150.png", pixhs, IFF_PNG);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
/* Get mask for connected regions */
pixm = pixCloseSafeBrick(NULL, pixr, 4, 4);
pixDisplayWrite(pixm, HT_DISP);
pixWrite("junk_ccmask.150.png", pixm, IFF_PNG);
/* Fill seed into mask to get halftone mask */
pixhm1 = pixSeedfillBinary(NULL, pixhs, pixm, 4);
pixDisplayWrite(pixhm1, HT_DISP);
pixWrite("junk_htmask.150.png", pixhm1, IFF_PNG);
pixhm2 = pixExpandBinaryPower2(pixhm1, 2);
/* Extract halftone stuff */
pixht = pixAnd(NULL, pixhm1, pixr);
pixWrite("junk_ht.150.png", pixht, IFF_PNG);
/* Extract non-halftone stuff */
pixnht = pixXor(NULL, pixht, pixr);
pixDisplayWrite(pixnht, TEXT_DISP);
pixWrite("junk_text.150.png", pixnht, IFF_PNG);
pixZero(pixht, &zero);
if (zero)
fprintf(stderr, "No halftone parts found\n");
else
fprintf(stderr, "Halftone parts found\n");
/* Get bit-inverted image */
pixi = pixInvert(NULL, pixnht);
pixWrite("junk_invert.150.png", pixi, IFF_PNG);
pixDisplayWrite(pixi, WS_MASK);
/* The whitespace mask will break textlines where there
* is a large amount of white space below or above.
* We can prevent this by identifying regions of the
* inverted image that have large horizontal (bigger than
* the separation between columns) and significant
* vertical extent (bigger than the separation between
* textlines), and subtracting this from the whitespace mask. */
pixt1 = pixMorphCompSequence(pixi, "o80.60", 0);
pixt2 = pixSubtract(NULL, pixi, pixt1);
pixDisplayWrite(pixt2, WS_MASK);
pixDestroy(&pixt1);
/* Identify vertical whitespace by opening inverted image */
pixt3 = pixOpenBrick(NULL, pixt2, 5, 1); /* removes thin vertical lines */
pixvws = pixOpenBrick(NULL, pixt3, 1, 200); /* gets long vertical lines */
pixDisplayWrite(pixvws, L_MAX(TEXT_DISP, WS_MASK));
pixWrite("junk_vertws.150.png", pixvws, IFF_PNG);
pixDestroy(&pixt2);
pixDestroy(&pixt3);
/* Get proto (early processed) text line mask. */
/* First close the characters and words in the textlines */
pixtm1 = pixCloseSafeBrick(NULL, pixnht, 30, 1);
pixDisplayWrite(pixtm1, TEXT_DISP);
pixWrite("junk_textmask1.150.png", pixtm1, IFF_PNG);
/* Next open back up the vertical whitespace corridors */
pixtm2 = pixSubtract(NULL, pixtm1, pixvws);
pixWrite("junk_textmask2.150.png", pixtm2, IFF_PNG);
/* Do a small opening to remove noise */
pixOpenBrick(pixtm2, pixtm2, 3, 3);
pixDisplayWrite(pixtm2, TEXT_DISP);
pixWrite("junk_textmask3.150.png", pixtm2, IFF_PNG);
pixtm3 = pixExpandBinaryPower2(pixtm2, 2);
/* Join pixels vertically to make text block mask */
pixtb1 = pixMorphSequence(pixtm2, "c1.10 + o4.1", 0);
pixDisplayWrite(pixtb1, BLOCK_DISP);
pixWrite("junk_textblock1.150.png", pixtb1, IFF_PNG);
/* Solidify the textblock mask and remove noise:
* (1) For each c.c., close the blocks and dilate slightly
* to form a solid mask.
* (2) Small horizontal closing between components
* (3) Open the white space between columns, again
* (4) Remove small components */
pixt1 = pixMorphSequenceByComponent(pixtb1, "c30.30 + d3.3", 8, 0, 0, NULL);
pixCloseSafeBrick(pixt1, pixt1, 10, 1);
pixDisplayWrite(pixt1, BLOCK_DISP);
pixt2 = pixSubtract(NULL, pixt1, pixvws);
pixt3 = pixSelectBySize(pixt2, 25, 5, 8, L_SELECT_IF_BOTH,
L_SELECT_IF_GTE, NULL);
pixDisplayWrite(pixt3, BLOCK_DISP);
pixWrite("junk_textblock2.150.png", pixt3, IFF_PNG);
pixtb2 = pixExpandBinaryPower2(pixt3, 2);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
pixDestroy(&pixt3);
/* Identify the outlines of each textblock */
ptaa = pixGetOuterBordersPtaa(pixtb2);
pixt1 = pixRenderRandomCmapPtaa(pixtb2, ptaa, 8, 1);
cmap = pixGetColormap(pixt1);
pixcmapResetColor(cmap, 0, 130, 130, 130); /* set interior to gray */
pixWrite("junk_textblock3.300.png", pixt1, IFF_PNG);
pixDisplayWithTitle(pixt1, 480, 360, "textblock mask with outlines", DFLAG);
ptaaDestroy(&ptaa);
pixDestroy(&pixt1);
/* Fill line mask (as seed) into the original */
pixt1 = pixSeedfillBinary(NULL, pixtm3, pixs, 8);
pixOr(pixtm3, pixtm3, pixt1);
pixDestroy(&pixt1);
pixWrite("junk_textmask.300.png", pixtm3, IFF_PNG);
pixDisplayWithTitle(pixtm3, 480, 360, "textline mask 4", DFLAG);
/* Fill halftone mask (as seed) into the original */
pixt1 = pixSeedfillBinary(NULL, pixhm2, pixs, 8);
pixOr(pixhm2, pixhm2, pixt1);
pixDestroy(&pixt1);
pixWrite("junk_htmask.300.png", pixhm2, IFF_PNG);
pixDisplayWithTitle(pixhm2, 520, 390, "halftonemask 2", DFLAG);
/* Find objects that are neither text nor halftones */
pixt1 = pixSubtract(NULL, pixs, pixtm3); /* remove text pixels */
pixnon = pixSubtract(NULL, pixt1, pixhm2); /* remove halftone pixels */
pixWrite("junk_other.300.png", pixnon, IFF_PNG);
pixDisplayWithTitle(pixnon, 540, 420, "other stuff", DFLAG);
pixDestroy(&pixt1);
/* Write out b.b. for text line mask and halftone mask components */
boxatm = pixConnComp(pixtm3, NULL, 4);
boxahm = pixConnComp(pixhm2, NULL, 8);
boxaWrite("junk_textmask.boxa", boxatm);
boxaWrite("junk_htmask.boxa", boxahm);
pixa = pixaReadFiles(".", "junk_write_display");
pixt1 = pixaDisplayTiledAndScaled(pixa, 8, 250, 4, 0, 25, 2);
pixWrite("junktiles", pixt1, IFF_JFIF_JPEG);
pixDestroy(&pixt1);
pixaDestroy(&pixa);
/* clean up to test with valgrind */
pixDestroy(&pixs);
pixDestroy(&pixr);
pixDestroy(&pixhs);
pixDestroy(&pixm);
pixDestroy(&pixhm1);
pixDestroy(&pixhm2);
pixDestroy(&pixht);
pixDestroy(&pixnht);
pixDestroy(&pixi);
pixDestroy(&pixvws);
pixDestroy(&pixtm1);
pixDestroy(&pixtm2);
pixDestroy(&pixtm3);
pixDestroy(&pixtb1);
pixDestroy(&pixtb2);
pixDestroy(&pixnon);
boxaDestroy(&boxatm);
boxaDestroy(&boxahm);
exit(0);
}
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