initial commit

Makefile

@@ -0,0 +1,18 @@
+CC = gcc
+CFLAGS = -Wall -g -L. -lm -O3 -march=native
+SOURCE = main.c
+TARGET = enhancer
+
+# Default target
+all: $(TARGET)
+
+# Rule to build the executable
+$(TARGET): $(SOURCE)
+	$(CC) $(CFLAGS) -o $@ $<
+
+# Rule to clean up object files and the executable
+clean:
+	rm -f $(TARGET) *.o
+
+# Phony targets
+.PHONY: all clean

main.c

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+#define STB_IMAGE_IMPLEMENTATION
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#define STBI_FAILURE_USERMSG
+
+#include "stb_image.h"
+#include "stb_image_write.h"
+
+/*
+0 - simple
+balanced
+1 - nomin
+average of two largest channels, bias towards darker shades, use if unsure
+2 - nomax
+makes image brighter
+3 - twist
+results in a specific style. largest banding potential, reduce strength (2024 update I don't remember how I came up with that)
+*/
+#define LUMINANCE_METHOD 1
+
+/*
+less is more (literally). Accepts decimals.
+go below 1 = regret
+negative causes b&w (although it does not colorize already b&w images)
+0 crashes
+*/
+#define VIBRANCE_STRENGTH 1.1
+
+/*
+this is to make things more natural but sometimes does the opposite so toggle if u get weird things (I have a fix in mind tho) (2024 update not anymore)
+basically darkens too bright things and vice versa
+uncomment to enable
+*/
+//#define BETTER_CLAMP
+
+const static inline int max(int a, int b) {
+    return a > b ? a : b;
+}
+
+const static inline int max3(int a, int b, int c) {
+    int ab = max(a, b);
+    return ab > c ? ab : c;
+}
+
+const static inline int min(int a, int b) {
+    return a < b ? a : b;
+}
+
+const static inline int min3(int a, int b, int c) {
+    int ab = min(a, b);
+    return ab < c ? ab : c;
+}
+
+#ifdef BETTER_CLAMP
+const static inline int cdiff(int n, int min, int max) {
+    if (n > max)
+        return max - (n - max);
+    else if (n < min) {
+        return min + (min - n);
+    }
+
+    return n;
+}
+
+const static inline int clamp(int n, int min, int max) {
+    return cdiff(n, min, max);
+} // I don't know if const static inline was needed
+#else
+const static inline int clamp(int n, int min, int max) {
+    return n > max ? max : (n < min ? min : n);
+}
+
+#endif
+
+void vibrancer(unsigned char *pixel) {
+    int r = pixel[0],
+        g = pixel[1],
+        b = pixel[2];
+
+    // TODO remove unnecessary calculations
+    int min_rgb = min3(r, g, b);
+    int max_rgb = max3(r, g, b);
+    int sum = r + g + b;
+
+    int m;
+
+    if (LUMINANCE_METHOD == 3) // twist
+        m = 3*sum - 4*(min_rgb + max_rgb);
+    else if (LUMINANCE_METHOD == 2) // nomax 
+        m = (sum - max_rgb) / 2;
+    else if (LUMINANCE_METHOD == 1) // nomin
+        m = (sum - min_rgb) / 2;
+    else // simple
+        m = sum / 3;
+
+    r -= (m - r) / VIBRANCE_STRENGTH;
+    g -= (m - g) / VIBRANCE_STRENGTH;
+    b -= (m - b) / VIBRANCE_STRENGTH;
+    
+    pixel[0] = clamp(r, 0, 255);
+    pixel[1] = clamp(g, 0, 255);
+    pixel[2] = clamp(b, 0, 255);
+
+}
+
+int main(int argc, char **argv) {
+    if (VIBRANCE_STRENGTH == 0) {
+        printf("VIBRANCE_STRENGTH cannot be zero");
+        return 1;
+    }
+
+    char* input = argv[1];
+    char* output = argv[2];
+
+    if (argc < 3) {
+        printf("Please specify input and output files\n");
+        return 2;
+    }
+
+    int width, height, channels;
+
+    unsigned char *img = stbi_load(input, &width, &height, &channels, 3);
+
+    if (img == NULL) {
+        printf("Error loading image\n");
+        printf("%s\n", stbi_failure_reason());
+        return 1;
+    }
+
+    if (channels < 3) {
+        printf("Not enough channels (%d)", channels);
+        return 1;
+    }    
+
+    for (int y=0; y<height; y++) {
+        for (int x=0; x<width; x++) {
+            unsigned char *pixel = img + (y * width + x) * channels;
+
+            vibrancer(pixel);
+        }
+    }
+
+    stbi_write_png(output, width, height, channels, img, width * channels);
+
+    return 0;
+}