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lazily adapt threshold to image

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Instead of adapting the threshold to the image before executing
commands, adapt the threshold just before it is needed.

This allows to avoid theshold adaptation when -p, --process-only
is used with only the "grayscale" and/or "mirror" commands.

This also prepares the code to allow introduction of a new option
to avoid adapting the threshold to the original image before the
"crop" command is applied.
This commit is contained in:
Erik Auerswald
2025-03-23 14:42:25 +01:00
parent 7cae796188
commit 94ce321060
5 changed files with 36 additions and 7 deletions
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NEWS
+2
View File
@@ -7,6 +7,8 @@ Version ?.??.? (????-??-??):
--iter-threshold are used together because -a inhibits -T
* Improved performance when reading image data via standard input
* Improved performance when using gray_stretch together with -g
* Improved performance when using option -p, --process-only together
with only the grayscale and/or mirror commands
* Documentation improvements
Version 2.24.1 (2024-12-11):
defines.h
+4
View File
@@ -172,6 +172,10 @@
/* default luminance formula */
#define DEFAULT_LUM_FORMULA REC709
/* when to adapt threshold values to the image */
#define INITIAL 0 /* adapt threshold unless is was already adapted */
#define UPDATE 1 /* adapt threshold even if it was adapted before */
/* foreground and background */
typedef enum fg_bg_e {
FG,
imgproc.c
+6 -2
View File
@@ -466,10 +466,13 @@ Imlib_Image make_mono(Imlib_Image *source_image, double thresh, luminance_t lt)
/* adapt threshold to image values values */
double adapt_threshold(Imlib_Image *image, double thresh, luminance_t lt,
unsigned int flags)
unsigned int flags, int force_update)
{
double t = thresh;
if(!(flags & ABSOLUTE_THRESHOLD)) {
static int is_adapted = 0;
if(is_adapted && !force_update) {
fprintf(stderr, "threshold is already adjusted to image\n");
} else if(!(flags & ABSOLUTE_THRESHOLD)) {
if(flags & DEBUG_OUTPUT)
fprintf(stderr, "adjusting threshold to image: %f ->", t);
t = get_threshold(image, thresh/100.0, lt, 0, 0, -1, -1);
@@ -482,6 +485,7 @@ double adapt_threshold(Imlib_Image *image, double thresh, luminance_t lt,
if(flags & DEBUG_OUTPUT)
fprintf(stderr, " %f\n", t);
}
is_adapted = 1;
}
if((flags & VERBOSE) || (flags & DEBUG_OUTPUT)) {
fprintf(stderr, "using threshold %.2f\n", t);
imgproc.h
+1 -1
View File
@@ -130,7 +130,7 @@ Imlib_Image crop(Imlib_Image *source_image, int x, int y, int w, int h);
/* adapt threshold to image values values */
double adapt_threshold(Imlib_Image *image, double thresh, luminance_t lt,
unsigned int flags);
unsigned int flags, int force_update);
/* compute dynamic threshold value from the rectangle (x,y),(x+w,y+h) of
* source_image */
ssocr.c
+23 -4
View File
@@ -735,9 +735,6 @@ int main(int argc, char **argv)
min, max);
}
/* adapt threshold to image */
thresh = adapt_threshold(&image, thresh, lt, flags);
/* process commands */
if(flags & VERBOSE) /* then print found commands */ {
if(optind >= argc-1) {
@@ -771,6 +768,7 @@ int main(int argc, char **argv)
n = 1;
if(flags & VERBOSE) fputs(" processing dilation (1)\n", stderr);
}
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = dilation(&image, thresh, lt, n);
imlib_context_set_image(image);
imlib_free_image();
@@ -790,6 +788,7 @@ int main(int argc, char **argv)
n = 1;
if(flags & VERBOSE) fputs(" processing erosion (1)\n", stderr);
}
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = erosion(&image, thresh, lt, n);
imlib_context_set_image(image);
imlib_free_image();
@@ -809,6 +808,7 @@ int main(int argc, char **argv)
n = 1;
if(flags & VERBOSE) fputs(" processing opening (1)\n", stderr);
}
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = opening(&image, thresh, lt, n);
imlib_context_set_image(image);
imlib_free_image();
@@ -828,18 +828,21 @@ int main(int argc, char **argv)
n = 1;
if(flags & VERBOSE) fputs(" processing closing (1)\n", stderr);
}
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = closing(&image, thresh, lt, n);
imlib_context_set_image(image);
imlib_free_image();
image = new_image;
} else if(strcasecmp("remove_isolated",argv[i]) == 0) {
if(flags & VERBOSE) fputs(" processing remove_isolated\n", stderr);
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = remove_isolated(&image, thresh, lt);
imlib_context_set_image(image);
imlib_free_image();
image = new_image;
} else if(strcasecmp("make_mono",argv[i]) == 0) {
if(flags & VERBOSE) fputs(" processing make_mono\n", stderr);
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = make_mono(&image, thresh, lt);
imlib_context_set_image(image);
imlib_free_image();
@@ -860,6 +863,7 @@ int main(int argc, char **argv)
if(flags & VERBOSE)
fputs(" processing white_border (1)\n", stderr);
}
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = white_border(&image, bdwidth);
imlib_context_set_image(image);
imlib_free_image();
@@ -874,6 +878,7 @@ int main(int argc, char **argv)
}
if(i+1<argc-1) {
offset = (int) atoi(argv[++i]); /* sideeffect: increment i */
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = shear(&image, offset);
imlib_context_set_image(image);
imlib_free_image();
@@ -893,6 +898,7 @@ int main(int argc, char **argv)
}
if(i+1<argc-1) {
mask = (int) atoi(argv[++i]); /* sideeffect: increment i */
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = set_pixels_filter(&image, thresh, lt, mask);
imlib_context_set_image(image);
imlib_free_image();
@@ -913,6 +919,7 @@ int main(int argc, char **argv)
}
if(i+1<argc-1) {
mask = (int) atoi(argv[++i]); /* sideeffect: increment i */
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = keep_pixels_filter(&image, thresh, lt, mask);
imlib_context_set_image(image);
imlib_free_image();
@@ -935,6 +942,7 @@ int main(int argc, char **argv)
fprintf(stderr, "\n");
}
i+=2; /* skip the arguments to dynamic_threshold */
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = dynamic_threshold(&image, thresh, lt, ww, wh);
imlib_context_set_image(image);
imlib_free_image();
@@ -946,30 +954,35 @@ int main(int argc, char **argv)
}
} else if(strcasecmp("rgb_threshold",argv[i]) == 0) {
if(flags & VERBOSE) fputs(" processing rgb_threshold\n", stderr);
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = make_mono(&image, thresh, MINIMUM);
imlib_context_set_image(image);
imlib_free_image();
image = new_image;
} else if(strcasecmp("r_threshold",argv[i]) == 0) {
if(flags & VERBOSE) fputs(" processing r_threshold\n", stderr);
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = make_mono(&image, thresh, RED);
imlib_context_set_image(image);
imlib_free_image();
image = new_image;
} else if(strcasecmp("g_threshold",argv[i]) == 0) {
if(flags & VERBOSE) fputs(" processing g_threshold\n", stderr);
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = make_mono(&image, thresh, GREEN);
imlib_context_set_image(image);
imlib_free_image();
image = new_image;
} else if(strcasecmp("b_threshold",argv[i]) == 0) {
if(flags & VERBOSE) fputs(" processing b_threshold\n", stderr);
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = make_mono(&image, thresh, BLUE);
imlib_context_set_image(image);
imlib_free_image();
image = new_image;
} else if(strcasecmp("invert",argv[i]) == 0) {
if(flags & VERBOSE) fputs(" processing invert\n", stderr);
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = invert(&image, thresh, lt);
imlib_context_set_image(image);
imlib_free_image();
@@ -1000,6 +1013,7 @@ int main(int argc, char **argv)
}
}
i+=2; /* skip the arguments to gray_stretch */
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = gray_stretch(&image, t1, t2, lt);
imlib_context_set_image(image);
imlib_free_image();
@@ -1033,6 +1047,7 @@ int main(int argc, char **argv)
fprintf(stderr, "\n");
}
i += 4; /* skip the arguments to crop */
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = crop(&image, x, y, cw, ch);
imlib_context_set_image(image);
imlib_free_image();
@@ -1053,7 +1068,7 @@ int main(int argc, char **argv)
" (lum should be in [0,255])\n", min, max);
}
/* adapt threshold to cropped image */
thresh = adapt_threshold(&image, thresh, lt, flags);
thresh = adapt_threshold(&image, thresh, lt, flags, UPDATE);
} else {
fprintf(stderr, "%s: error: crop command needs 4 arguments\n", PROG);
exit(99);
@@ -1068,6 +1083,7 @@ int main(int argc, char **argv)
fprintf(stderr, "\n");
}
theta = atof(argv[++i]); /* sideeffect: increment i */
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
new_image = rotate(&image, theta);
imlib_context_set_image(image);
imlib_free_image();
@@ -1117,6 +1133,9 @@ int main(int argc, char **argv)
/* exit if only image processing shall be done */
if(flags & PROCESS_ONLY) exit(3);
/* adapt threshold to image (unless this is already done) */
thresh = adapt_threshold(&image, thresh, lt, flags, INITIAL);
if(flags & USE_DEBUG_IMAGE) {
/* copy processed image to debug image */
debug_image = make_mono(&image, thresh, lt);