+ unsigned char bg_red = 180;
+ unsigned char bg_green = 180;
+ unsigned char bg_blue = 180;
+
+ unsigned char mask_red = image.GetMaskRed();
+ unsigned char mask_green = image.GetMaskGreen();
+ unsigned char mask_blue = image.GetMaskBlue();
+
+ bool has_mask = image.HasMask();
+
+ int x,y;
+ for (y = 0; y < image.GetHeight(); y++)
+ {
+ for (x = 0; x < image.GetWidth(); x++)
+ {
+ unsigned char red = image.GetRed(x,y);
+ unsigned char green = image.GetGreen(x,y);
+ unsigned char blue = image.GetBlue(x,y);
+ if (!has_mask || red != mask_red || green != mask_green || blue != mask_blue)
+ {
+ red = (((wxInt32) red - bg_red) >> 1) + bg_red;
+ green = (((wxInt32) green - bg_green) >> 1) + bg_green;
+ blue = (((wxInt32) blue - bg_blue) >> 1) + bg_blue;
+ image.SetRGB( x, y, red, green, blue );
+ }
+ }
+ }