On Thu, Jan 11, 2007 at 10:47:10PM +0100, Laurent Pinchart wrote:
> Hi Luca,
>
> > This is function in C to convert from Bayer to RGB24 pixel formats.
> > The linear interpolation is more efficient than the ones I saw in other
> > similar functions on internet, as the code omits "if-then-else" conditional
> > statements in the loops.
>
> Thanks for the code. This will be usefull for all the users who are
> interested
> in raw image processing. There seem to be quite a lot of them lately :-)
That is easy to explain: Those interested in raw processing are looking
for a webcam that can do USB 2.0 and is supported on Linux. Not that
much choice. ;)
Btw, my take on Bayer->RGB processing: (attached)
--
Vojtech Pavlik
Director SuSE Labs
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <string.h>
#include <sys/select.h>
#define u8 uint8_t
#define u16 uint16_t
#define u32 uint32_t
static uint8_t rgb[640*480*3];
#define R(x,y) pRGB24[0 + 3 * ((x) + 640 * (y))]
#define G(x,y) pRGB24[1 + 3 * ((x) + 640 * (y))]
#define B(x,y) pRGB24[2 + 3 * ((x) + 640 * (y))]
#define Bay(x,y) pBay[(x) + 640 * (y)]
static void bayer_copy(u8 *pBay, u8 *pRGB24, int x, int y)
{
G(x + 0, y + 0) = Bay(x + 0, y + 0);
G(x + 1, y + 1) = Bay(x + 1, y + 1);
G(x + 0, y + 1) = G(x + 1, y + 0) = ((u32)Bay(x + 0, y + 0) +
(u32)Bay(x + 1, y + 1)) / 2;
R(x + 0, y + 0) = R(x + 1, y + 0) = R(x + 1, y + 1) = R(x + 0, y + 1) =
Bay(x + 0, y + 1);
B(x + 1, y + 1) = B(x + 0, y + 0) = B(x + 0, y + 1) = B(x + 1, y + 0) =
Bay(x + 1, y + 0);
}
static void bayer_bilinear(u8 *pBay, u8 *pRGB24, int x, int y)
{
R(x + 0, y + 0) = ((u32)Bay(x + 0, y + 1) + (u32)Bay(x + 0, y - 1)) / 2;
G(x + 0, y + 0) = Bay(x + 0, y + 0);
B(x + 0, y + 0) = ((u32)Bay(x - 1, y + 0) + (u32)Bay(x + 1, y + 0)) / 2;
R(x + 0, y + 1) = Bay(x + 0, y + 1);
G(x + 0, y + 1) = ((u32)Bay(x + 0, y + 0) + (u32)Bay(x + 0, y + 2)
+ (u32)Bay(x - 1, y + 1) + (u32)Bay(x + 1, y + 1)) / 4;
B(x + 0, y + 1) = ((u32)Bay(x + 1, y + 0) + (u32)Bay(x - 1, y + 0)
+ (u32)Bay(x + 1, y + 2) + (u32)Bay(x - 1, y + 2)) / 4;
R(x + 1, y + 0) = ((u32)Bay(x + 0, y + 1) + (u32)Bay(x + 2, y + 1)
+ (u32)Bay(x + 0, y - 1) + (u32)Bay(x + 2, y - 1)) / 4;
G(x + 1, y + 0) = ((u32)Bay(x + 0, y + 0) + (u32)Bay(x + 2, y + 0)
+ (u32)Bay(x + 1, y - 1) + (u32)Bay(x + 1, y + 1)) / 4;
B(x + 1, y + 0) = Bay(x + 1, y + 0);
R(x + 1, y + 1) = ((u32)Bay(x + 0, y + 1) + (u32)Bay(x + 2, y + 1)) / 2;
G(x + 1, y + 1) = Bay(x + 1, y + 1);
B(x + 1, y + 1) = ((u32)Bay(x + 1, y + 0) + (u32)Bay(x + 1, y + 2)) / 2;
}
static void bayer_to_rgb24(u8 *pBay, u8 *pRGB24)
{
int i, j;
for (i = 0; i < 640; i += 2)
for (j = 0; j < 480; j += 2)
if (i == 0 || j == 0 || i == 640 - 2 || j == 480 - 2)
bayer_copy(pBay, pRGB24, i, j);
else
bayer_bilinear(pBay, pRGB24, i, j);
}
void writepnm(uint8_t *data, int i)
{
FILE *fd;
char name[32];
sprintf(name, "p5-%04d.pnm", i);
fd = fopen(name, "w");
fputs("P6\n", fd);
fputs("640 480\n", fd);
fputs("255\n", fd);
fwrite(data, 640*480*3, 1, fd);
fclose(fd);
}
int main(void)
{
int fdi;
u8 *ibot;
if ((fdi = open("bayer.raw", O_RDONLY)) < 0) {
perror("open");
return -1;
}
if ((ibot = mmap(NULL, 640 * 480 + 640*4, PROT_READ, MAP_SHARED, fdi,
0)) == MAP_FAILED) {
perror("mmap");
return -1;
}
bayer_to_rgb24(ibot, rgb);
writepnm(rgb, 0);
close(fdi);
return 0;
}
_______________________________________________
Linux-uvc-devel mailing list
[email protected]
https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
