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Small bitmap dithering tweak

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11191 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2006-10-11 18:12:36 +00:00
parent 6a4ec1414d
commit bed0db213d
1 changed files with 17 additions and 11 deletions
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28
apps/recorder/bmp.c
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@ -97,14 +97,10 @@ inline int getpix(int px, unsigned char *bmpbuf) {
#if LCD_DEPTH == 16 #if LCD_DEPTH == 16
/* Cheapo 24 -> 16 bit dither */ /* Cheapo 24 -> 16 bit dither */
#if LCD_PIXELFORMAT == RGB565SWAPPED
#define RGBSWAPPED(rgb) swap16(rgb)
#else
#define RGBSWAPPED(rgb) rgb
#endif
static unsigned short dither_24_to_16(struct rgb_quad rgb, int row, int col) static unsigned short dither_24_to_16(struct rgb_quad rgb, int row, int col)
{ {
static const unsigned char dith[2][16] = { static const unsigned char dith[][16] =
{
{ /* 5 bit */ { /* 5 bit */
0,6,1,7, 0,6,1,7,
4,2,5,3, 4,2,5,3,
@ -116,15 +112,25 @@ static unsigned short dither_24_to_16(struct rgb_quad rgb, int row, int col)
2,1,2,1, 2,1,2,1,
0,3,0,3, 0,3,0,3,
2,1,2,1 2,1,2,1
} },
}; };
const int elm = (row & 3) + ((col & 3) << 2); const int elm = (row & 3) + ((col & 3) << 2);
short b = 31*((unsigned short)rgb.blue + dith[0][elm]) >> 8; unsigned short color;
short g = 63*((unsigned short)rgb.green + dith[1][elm]) >> 8;
short r = 31*((unsigned short)rgb.red + dith[0][elm]) >> 8;
return RGBSWAPPED(b | (g << 5) | (r << 11)); unsigned b = ((unsigned)rgb.blue + dith[0][elm]) >> 3;
if (b > 0x1f) b = 0x1f;
unsigned g = ((unsigned)rgb.green + dith[1][elm]) >> 2;
if (g > 0x3f) g = 0x3f;
unsigned r = ((unsigned)rgb.red + dith[0][elm]) >> 3;
if (r > 0x1f) r = 0x1f;
color = (unsigned short)(b | (g << 5) | (r << 11));
#if LCD_PIXELFORMAT == RGB565SWAPPED
swap16(color);
#endif
return color;
} }
#endif /* LCD_DEPTH == 16 */ #endif /* LCD_DEPTH == 16 */