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/* A tiny example operation. This adds two uchar images to make a ushort
* image.
*
* It only outputs the common pixels, so both inputs are cropped to the common
* size in all three dimensions (width, height, bands).
*
* compile with
*
* gcc my-add.c -g -Wall `pkg-config vips --cflags --libs`
*
* (derived from code by @prasadbandodkar with thanks)
*/
#include <vips/vips.h>
#include <stdio.h>
static int
my_add_generate(VipsRegion *out_region,
void *vseq, void *a, void *b, gboolean *stop)
{
// output area and output image
VipsRect *r = &out_region->valid;
VipsImage *out = out_region->im;
// input regions and input images
VipsRegion **ir = (VipsRegion **) vseq;
VipsImage **inputs = (VipsImage **) a;
// request matching part of input regions
if (vips_reorder_prepare_many(out_region->im, ir, r))
return -1;
for (int y = 0; y < r->height; y++)
{
unsigned char *p1 = VIPS_REGION_ADDR(ir[0], r->left, r->top + y);
unsigned char *p2 = VIPS_REGION_ADDR(ir[1], r->left, r->top + y);
unsigned short *q = (unsigned short *)
VIPS_REGION_ADDR(out_region, r->left, r->top + y);
for (int x = 0; x < r->width; x++) {
for (int b = 0; b < out->Bands; b++)
q[b] = p1[b] + p2[b];
p1 += inputs[0]->Bands;
p2 += inputs[1]->Bands;
q += out->Bands;
}
}
return 0;
}
static int
my_add_operation(VipsImage *in1, VipsImage *in2, VipsImage **out_reference)
{
// we only work for uchar images
if (vips_check_format("try", in1, VIPS_FORMAT_UCHAR) ||
vips_check_format("try", in2, VIPS_FORMAT_UCHAR))
return -1;
// make the output image
VipsImage *out = vips_image_new();
// make a self-freeing, null-terminated array of input images
VipsImage **inputs = vips_allocate_input_array(out, in1, in2, NULL);
if (vips_image_pipeline_array(out, VIPS_DEMAND_STYLE_THINSTRIP, inputs)) {
g_object_unref(out);
return -1;
}
// out will inherit all the properties of the inputs ... we must override
// the ones we want to change (dimensions and format)
out->Xsize = VIPS_MIN(in1->Xsize, in2->Xsize);
out->Ysize = VIPS_MIN(in1->Ysize, in2->Ysize);
out->Bands = VIPS_MIN(in1->Bands, in2->Bands);
out->BandFmt = VIPS_FORMAT_USHORT;
// generate pixels
if (vips_image_generate(out,
vips_start_many, my_add_generate, vips_stop_many, inputs, NULL)) {
g_object_unref(out);
return -1;
}
// success! set the output pointer
*out_reference = out;
return 0;
}
int
main(int argc, char **argv)
{
// initialize vips
if (VIPS_INIT(argv[0]))
vips_error_exit("try");
if (argc != 4)
vips_error_exit("usage: %s in1 in2 out", argv[0]);
// open inputs ... sequential access is fine for our operation
VipsImage *in1 = vips_image_new_from_file(argv[1],
"access", VIPS_ACCESS_SEQUENTIAL,
NULL);
VipsImage *in2 = vips_image_new_from_file(argv[2],
"access", VIPS_ACCESS_SEQUENTIAL,
NULL);
// call our operation
VipsImage *out;
if (my_add_operation(in1, in2, &out)) {
g_object_unref(in1);
g_object_unref(in2);
vips_error_exit("try");
}
// save the result
if (vips_image_write_to_file(out, argv[3], NULL)) {
g_object_unref(in1);
g_object_unref(in2);
g_object_unref(out);
vips_error_exit("try");
}
// release any resources
g_object_unref(in1);
g_object_unref(in2);
g_object_unref(out);
return 0;
}
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