[afterimage] correctly normalize 5-bit bmp color to 32-bit buffer

This is needed for correct color normalization, since buf-> expects a range between 0 and 255 but data contains 5-bit colors from 0 to 31.

Author: ferdymercury

graf2d/asimage/src/libAfterImage/bmp.c

@@ -83,9 +83,12 @@ dib_data_to_scanline( ASScanline *buf,
 			{
 				CARD8 c1 = data[2 * x];
 				CARD8 c2 = data[2 * x + 1];
-				buf->blue[x] =    c1&0x1F;
-				buf->green[x] = ((c1>>5)&0x07)|((c2<<3)&0x18);
-				buf->red[x] =   ((c2>>2)&0x1F);
+				// Assumed RGB555, ie R.G.B.A.X 5.5.5.0.1
+				const CARD32 bufmax = 0xFF;
+				const CARD32 chmax = 0x1F;
+				buf->blue[x] = ((c1 & 0x1F) * bufmax) / chmax;
+				buf->green[x] = ((((c1 >> 5) & 0x07) | ((c2 << 3) & 0x18)) * bufmax) / chmax;
+				buf->red[x] = ((((c2 >> 2) & 0x1F)) * bufmax) / chmax;
 			}
 			break ;
 		default: