Convert YUV to RGB
/* convert a YUV set to a rgb set - thanks to MartinS and
http://www.efg2.com/lab/Graphics/Colors/YUV.htm */
static void yuvtorgb(int Y, int U, int V, u8 *rgb)
{
int r, g, b;
static short L1[256], L2[256], L3[256], L4[256], L5[256];
static int initialised;
if (!initialised) {
int i;
initialised=1;
for (i=0;i<256;i++) {
L1[i] = 1.164*(i-16);
L2[i] = 1.596*(i-128);
L3[i] = -0.813*(i-128);
L4[i] = 2.018*(i-128);
L5[i] = -0.391*(i-128);
}
}
#if 0
r = 1.164*(Y-16) + 1.596*(V-128);
g = 1.164*(Y-16) - 0.813*(U-128) - 0.391*(V-128);
b = 1.164*(Y-16) + 2.018*(U-128);
#endif
r = L1[Y] + L2[V];
g = L1[Y] + L3[U] + L5[V];
b = L1[Y] + L4[U];
if (r < 0) r = 0;
if (g < 0) g = 0;
if (b < 0) b = 0;
if (r > 255) r = 255;
if (g > 255) g = 255;
if (b > 255) b = 255;
rgb[0] = r;
rgb[1] = g;
rgb[2] = b;
}
/* convert yuv to rgb */
void yuv_convert(u8 *buf, u8 *rgb, int xsize, int ysize)
{
int i;
for (i=0;i<xsize*ysize;i+=2) {
int Y1, Y2, U, V;
Y1 = buf[2*i+0];
Y2 = buf[2*i+2];
U = buf[2*i+1];
V = buf[2*i+3];
yuvtorgb(Y1, U, V, &rgb[3*i]);
yuvtorgb(Y2, U, V, &rgb[3*(i+1)]);
}
}
/* this is _really_ weird */
void yuv_block_convert(u8 *buf, u8 *rgb, int xsize, int ysize)
{
u8 Y[128], U[64], V[64];
int i, j, x, y, xx, yy;
memset(Y, 32, sizeof(Y));
memset(U, 32, sizeof(U));
memset(V, 32, sizeof(V));
#define YINC 8
#define XINC 16
for (y=0;y<ysize;y+=YINC) {
for (x=0;x<xsize;x+=XINC) {
memcpy(Y, buf, 128);
memcpy(U, buf+128, 64);
memcpy(V, buf+192, 64);
buf += 256;
for (i=0;i<128;i+=2) {
xx = i%16;
yy = i/16;
if (xx < 8 && yy < 8) {
j = yy*8 + xx;
} else if (xx >= 8 && yy < 8) {
j = 64 + yy*8 + (xx-8);
} else if (xx < 8 && yy >= 8) {
j = yy*8 + xx;
} else {
j = 64 + yy*8 + xx-8;
}
yuvtorgb(Y[j], U[i>>1], V[i>>1],
&rgb[3*((y+yy)*xsize+(x+xx))]);
yuvtorgb(Y[j+1], U[i>>1], V[i>>1],
&rgb[3*((y+yy)*xsize+(x+xx+1))]);
}
}
}
}