1.0: init version

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "src/stb"]
+	path = src/stb
+	url = https://github.com/nothings/stb

LICENSE

@@ -0,0 +1,24 @@
+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+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 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.
+
+For more information, please refer to <https://unlicense.org>

Makefile

@@ -0,0 +1,12 @@
+PNAME = stbithresedgediv
+CFLAGS = -std=c99 -O2 -Wall -Wextra -Wno-unused-but-set-variable -Wno-unused-parameter -Werror
+LDLIBS = -lm -s
+SRCS = src/edgediv.c
+
+all: $(PNAME)
+
+$(PNAME): $(SRCS)
+	$(CC) $(CFLAGS) $^ $(LDLIBS) -o $@
+
+clean:
+	rm -f $(PNAME)

README.md

@@ -0,0 +1,64 @@
+# stbithresedgediv
+
+EdgeDiv ("EdgePlus" + "BlurDiv") threshold an image based of Gauss blur.
+Used:
+* Gauss blur: [iir_gauss_blur](https://github.com/arkanis/iir_gauss_blur).
+* STB: [stb](https://github.com/nothings/stb).
+
+```
+    O = (E < T) ? BLACK : WHITE
+
+      T = ThresholdBimadal(E)
+
+        E = FilterEdgeDiv(I, B)
+        
+          B = FilterBlur(I)
+
+    bounds:
+            BLACK, if E < lower,
+            WHITE, if E > upper.
+```
+
+This filter was first applied in [STEX](https://github.com/ImageProcessing-ElectronicPublications/scantailor-experimental) (2023)
+in a single-component version (Y).
+
+Here this filter is implemented in a full-color version.
+
+## Usage
+
+`./stbithresedgediv [-h] [-i] [-s sigma] [-k coeff] [-d delta] [-l lower] [-u upper] input-file output.png`
+
+`-s sigma`     The sigma of the gauss normal distribution (number >= 0.5).
+               Larger values result in a stronger blur.
+
+`-k coeff`     The coefficient local threshold.
+
+`-d delta`     The regulator threshold.
+
+`-l lower`     The bound lower threshold.
+
+`-u upper`     The bound upper threshold.
+
+`-i`           Info to `stdout`.
+
+`-h`           display this help and exit.
+
+You can use either sigma to specify the strengh of the blur.
+
+The performance is independent of the blur strengh (sigma). This tool is an
+implementation of the paper "Recursive implementaion of the Gaussian filter"
+by Ian T. Young and Lucas J. van Vliet.
+
+stb_image and stb_image_write by Sean Barrett and others is used to read and
+write images.
+
+## Installation
+
+- Clone the repo or download the source `git clone --recurse-submodules https://github.com/ImageProcessing-ElectronicPublications/stbithresedgediv`
+- Execute `make`
+- Done. Either use the `stbithresedgediv` executable directly or copy it somewhere in your PATH.
+
+## Links
+
+* STB: [stb](https://github.com/nothings/stb).
+* Gauss blur: [iir_gauss_blur](https://github.com/arkanis/iir_gauss_blur).

src/edgediv.c

@@ -0,0 +1,148 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <unistd.h>
+
+#define STB_IMAGE_IMPLEMENTATION
+#define STBI_FAILURE_USERMSG
+#include "stb/stb_image.h"
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb/stb_image_write.h"
+#define IIR_GAUSS_BLUR_IMPLEMENTATION
+#include "iir_gauss_blur.h"
+#define THRESHOLD_EDGEDIV_IMPLEMENTATION
+#include "thresedgediv.h"
+
+void usage(char* progname)
+{
+    fprintf(stderr,
+        "%s %s %s\n",
+        "Usage:", progname, "[-h] [-i] [-s sigma] [-k coeff] [-d delta] [-l lower] [-u upper] input-file output.png\n"
+        "EdgeDiv (EdgePlus + BlurDiv) threshold an image and save it as PNG.\n"
+     );
+}
+
+void help(float sigma, float coef, float delta, unsigned char bound_lower, unsigned char bound_upper)
+{
+    fprintf(stderr,
+        "%s %f %s %f %s %f %s %d %s %d %s\n",
+        "  -s sigma     The sigma of the gauss normal distribution (number >= 0.5, default =", sigma, ").\n"
+        "               Larger values result in a stronger blur.\n"
+        "  -k coeff     The coefficient local threshold (number, default =", coef, ").\n"
+        "  -d delta     The regulator threshold (number, default =", delta, ").\n"
+        "  -l lower     The bound lower threshold (integer, default =", bound_lower, ").\n"
+        "  -u upper     The bound upper threshold (integer, default =", bound_upper, ").\n"
+        "  -i           info to stdout.\n"
+        "  -h           display this help and exit.\n"
+        "\n"
+        "You can use either sigma to specify the strengh of the blur.\n"
+        "\n"
+        "The performance is independent of the blur strengh (sigma). This tool is an\n"
+        "implementation of the paper \"Recursive implementaion of the Gaussian filter\"\n"
+        "by Ian T. Young and Lucas J. van Vliet.\n"
+        "\n"
+        "stb_image and stb_image_write by Sean Barrett and others is used to read and\n"
+        "write images.\n"
+    );
+}
+
+unsigned char* image_copy(unsigned int width, unsigned int height, unsigned char components, unsigned char* image)
+{
+    size_t image_size = height * width * components;
+    unsigned char* dest = (unsigned char*)malloc(image_size * sizeof(unsigned char));
+    if (dest != NULL)
+    {
+        for (size_t i = 0; i < image_size; i++)
+        {
+            dest[i] = image[i];
+        }
+    }
+    return dest;
+}
+
+int main(int argc, char** argv)
+{
+    int info = 0;
+    float sigma = 10.0f;
+    float coef = 0.75f;
+    float delta = 0.0f;
+    unsigned char bound_lower = 0;
+    unsigned char bound_upper = 255;
+
+    int opt;
+    while ( (opt = getopt(argc, argv, "is:k:d:l:u:h")) != -1 )
+    {
+        switch(opt)
+        {
+            case 'i':
+                info = 1;
+                break;
+            case 's':
+                sigma = strtof(optarg, NULL);
+                break;
+            case 'k':
+                coef = strtof(optarg, NULL);
+                break;
+            case 'd':
+                delta = strtof(optarg, NULL);
+                break;
+            case 'l':
+                bound_lower = strtol(optarg, NULL, 10);
+                break;
+            case 'u':
+                bound_upper = strtol(optarg, NULL, 10);
+                break;
+            case 'h':
+                usage(argv[0]);
+                help(sigma, coef, delta, bound_lower, bound_upper);
+                return 0;
+            default:
+                usage(argv[0]);
+                return 1;
+        }
+    }
+
+    // Need at least two filenames after the last option
+    if (argc < optind + 2)
+    {
+        usage(argv[0]);
+        return 1;
+    }
+
+    int width = 0, height = 0, components = 1;
+    unsigned char* image = stbi_load(argv[optind], &width, &height, &components, 0);
+    if (image == NULL)
+    {
+        fprintf(stderr, "Failed to load %s: %s.\n", argv[optind], stbi_failure_reason());
+        return 2;
+    }
+
+    unsigned char* blur = image_copy(width, height, components, image);
+    if (blur == NULL)
+    {
+        fprintf(stderr, "ERROR: not use memmory\n");
+        return 3;
+    }
+
+    if (info > 0)
+    {
+        fprintf(stderr, "INFO: image %s\n", argv[optind]);
+        fprintf(stderr, "INFO: width %d\n", width);
+        fprintf(stderr, "INFO: height %d\n", height);
+        fprintf(stderr, "INFO: components %d\n", components);
+        fprintf(stderr, "INFO: sigma %f\n", sigma);
+        fprintf(stderr, "INFO: coeff. %f\n", coef);
+        fprintf(stderr, "INFO: delta %f\n", delta);
+        fprintf(stderr, "INFO: bound lower %d\n", bound_lower);
+        fprintf(stderr, "INFO: bound upper %d\n", bound_upper);
+    }
+    iir_gauss_blur(width, height, components, blur, sigma);
+    image_threshold_edgediv(width, height, components, coef, delta, bound_lower, bound_upper, info, image, blur);
+
+    if ( stbi_write_png(argv[optind+1], width, height, components, image, 0) == 0 )
+    {
+        fprintf(stderr, "Failed to save %s.\n", argv[optind+1]);
+        return 4;
+    }
+
+    return 0;
+}