* Resizing in libpipi is now gamma-aware.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2247 92316355-f0b4-4df1-b90c-862c8a59935f

genethumb/genethumb.c

@@ -8,7 +8,7 @@ int main(void)
     pipi_image_t *i, *j;
 
     i = pipi_load("irc.png");
-    j = pipi_resize(i, 240, 240);
+    j = pipi_resize(i, 180, 180);
     pipi_save(j, "irc.bmp");
     pipi_free(i);
     pipi_free(j);

pipi/pixels.c

@@ -16,16 +16,21 @@
  * pixels.c: pixel-level image manipulation
  */
 
+#include "config.h"
+#include "common.h"
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include "config.h"
-#include "common.h"
+#include <math.h>
 
 #include "pipi_internals.h"
 #include "pipi.h"
 
+#define C2I(p) ((int)255.999*pow(((double)p)/255., 2.2))
+#define I2C(p) ((int)255.999*pow(((double)p)/255., 1./2.2))
+
 int pipi_getgray(pipi_image_t const *img, int x, int y, int *g)
 {
     if(x < 0 || y < 0 || x >= img->width || y >= img->height)
@@ -42,6 +47,8 @@ int pipi_getgray(pipi_image_t const *img, int x, int y, int *g)
 int pipi_getpixel(pipi_image_t const *img,
                   int x, int y, int *r, int *g, int *b)
 {
+    uint8_t *pixel;
+
     if(x < 0 || y < 0 || x >= img->width || y >= img->height)
     {
         *r = 255;
@@ -50,21 +57,27 @@ int pipi_getpixel(pipi_image_t const *img,
         return -1;
     }
 
-    *b = (unsigned char)img->pixels[y * img->pitch + x * img->channels];
-    *g = (unsigned char)img->pixels[y * img->pitch + x * img->channels + 1];
-    *r = (unsigned char)img->pixels[y * img->pitch + x * img->channels + 2];
+    pixel = img->pixels + y * img->pitch + x * img->channels;
+
+    *b = C2I((unsigned char)pixel[0]);
+    *g = C2I((unsigned char)pixel[1]);
+    *r = C2I((unsigned char)pixel[2]);
 
     return 0;
 }
 
 int pipi_setpixel(pipi_image_t *img, int x, int y, int r, int g, int b)
 {
+    uint8_t *pixel;
+
     if(x < 0 || y < 0 || x >= img->width || y >= img->height)
         return -1;
 
-    img->pixels[y * img->pitch + x * img->channels] = b;
-    img->pixels[y * img->pitch + x * img->channels + 1] = g;
-    img->pixels[y * img->pitch + x * img->channels + 2] = r;
+    pixel = img->pixels + y * img->pitch + x * img->channels;
+
+    pixel[0] = I2C(b);
+    pixel[1] = I2C(g);
+    pixel[2] = I2C(r);
 
     return 0;
 }