Changeset 2846Tweet

Timestamp:

Sep 28, 2008, 7:01:56 PM (14 years ago)

Author:

Sam Hocevar

Message:

Add a --gamma command to modify the global gamma value. This is a nasty
hack that will hopefully disappear in the future. The default gamma is
now 2.2 again (sRGB approximation).

Location:

libpipi/trunk

Files:

• pipi/context.c (modified) (1 diff)
• pipi/pipi.h (modified) (1 diff)
• pipi/pixels.c (modified) (5 diffs)
• src/pipi.c (modified) (1 diff)

libpipi/trunk/pipi/context.c

@@ -71 +71 @@
         pipi_save(ctx->images[ctx->nimages], file);
         pipi_free(ctx->images[ctx->nimages]);
+    }
+    else if(!strcmp(cmd, "gamma"))
+    {
+        char const *val;
+        va_list ap;
+
+        va_start(ap, cmd);
+        val = va_arg(ap, char const *);
+        va_end(ap);
+
+        pipi_set_gamma(atof(val));
     }
     else if(!strcmp(cmd, "dither"))

libpipi/trunk/pipi/pipi.h

@@ -119 +119 @@
 extern int pipi_save(pipi_image_t *, const char *);
 
+extern void pipi_set_gamma(double);
 extern pipi_pixels_t *pipi_getpixels(pipi_image_t *, pipi_format_t);
 extern int pipi_get_image_width(pipi_image_t *img);

libpipi/trunk/pipi/pixels.c

@@ -29 +29 @@
 #include "pipi_internals.h"
 
-#define GAMMA 1.0
-
 static void init_tables(void);
+
+static double global_gamma = 2.2;
+static int done = 0;
 
 static float u8tof32_table[256];
 static inline float u8tof32(uint8_t p) { return u8tof32_table[(int)p]; }
-
 
 /* Return a direct pointer to an image's pixels. */
@@ -153 +153 @@
                     if(p < 0.) d = 0.;
                     else if(p > 1.) d = 255;
-                    else d = (int)(255.999 * pow(p, 1. / GAMMA));
+                    else d = (int)(255.999 * pow(p, 1. / global_gamma));
 
                     dest[4 * (y * img->w + x) + i] = d;
@@ -189 +189 @@
                     if(p < 0.) d = 0.;
                     else if(p > 1.) d = 255;
-                    else d = (int)(255.999 * pow(p, 1. / GAMMA));
+                    else d = (int)(255.999 * pow(p, 1. / global_gamma));
 
                     dest[3 * (y * img->w + x) + i] = d;
@@ -252 +252 @@
 }
 
+void pipi_set_gamma(double g)
+{
+    if(g > 0.)
+    {
+        global_gamma = g;
+        done = 0;
+    }
+}
 
 static void init_tables(void)
 {
-    static int done = 0;
     int i;
 
@@ -262 +269 @@
 
     for(i = 0; i < 256; i++)
-        u8tof32_table[i] = pow((double)i / 255., GAMMA);
+        u8tof32_table[i] = pow((double)i / 255., global_gamma);
 
     done = 1;
 }
+

libpipi/trunk/src/pipi.c

@@ -34 +34 @@
             argv++;
         }
+        else if(!strcmp(argv[0], "--gamma"))
+        {
+            if(argv[1] == NULL)
+                return EXIT_FAILURE;
+            if(pipi_command(ctx, "gamma", argv[1]) != 0)
+                return EXIT_FAILURE;
+            argv++;
+        }
         else if(!strcmp(argv[0], "--scale"))
         {