Megapixels/quickpreview.c

/*
 * Fast but bad debayer method that scales and rotates by skipping source
 * pixels and doesn't interpolate any values at all
 */

#include <linux/videodev2.h>
#include "quickpreview.h"

/* Linear -> sRGB lookup table */
static const int srgb[] = {
	0, 12, 21, 28, 33, 38, 42, 46, 49, 52, 55, 58, 61, 63, 66, 68, 70,
	73, 75, 77, 79, 81, 82, 84, 86, 88, 89, 91, 93, 94, 96, 97, 99, 100,
	102, 103, 104, 106, 107, 109, 110, 111, 112, 114, 115, 116, 117, 118,
	120, 121, 122, 123, 124, 125, 126, 127, 129, 130, 131, 132, 133, 134,
	135, 136, 137, 138, 139, 140, 141, 142, 142, 143, 144, 145, 146, 147,
	148, 149, 150, 151, 151, 152, 153, 154, 155, 156, 157, 157, 158, 159,
	160, 161, 161, 162, 163, 164, 165, 165, 166, 167, 168, 168, 169, 170,
	171, 171, 172, 173, 174, 174, 175, 176, 176, 177, 178, 179, 179, 180,
	181, 181, 182, 183, 183, 184, 185, 185, 186, 187, 187, 188, 189, 189,
	190, 191, 191, 192, 193, 193, 194, 194, 195, 196, 196, 197, 197, 198,
	199, 199, 200, 201, 201, 202, 202, 203, 204, 204, 205, 205, 206, 206,
	207, 208, 208, 209, 209, 210, 210, 211, 212, 212, 213, 213, 214, 214,
	215, 215, 216, 217, 217, 218, 218, 219, 219, 220, 220, 221, 221, 222,
	222, 223, 223, 224, 224, 225, 226, 226, 227, 227, 228, 228, 229, 229,
	230, 230, 231, 231, 232, 232, 233, 233, 234, 234, 235, 235, 236, 236,
	237, 237, 237, 238, 238, 239, 239, 240, 240, 241, 241, 242, 242, 243,
	243, 244, 244, 245, 245, 245, 246, 246, 247, 247, 248, 248, 249, 249,
	250, 250, 251, 251, 251, 252, 252, 253, 253, 254, 254, 255
};

static void quick_debayer_set_dst(uint8_t *dst, uint8_t p0, uint8_t p1,
				  uint8_t p2)
{
	dst[0] = p0;
	dst[1] = p1;
	dst[2] = p2;
}

void quick_debayer(const uint8_t *source, uint8_t *destination,
		   uint32_t pix_fmt, int width, int height, int skip,
		   int blacklevel)
{
	int byteskip = 2 * skip;
	int input_size = width * height;
	int i = 0, j = 0;
	int row_left = width;

	do {
		uint8_t b0 = srgb[source[i] - blacklevel];
		uint8_t b1 = srgb[source[i + 1] - blacklevel];
		uint8_t b2 = srgb[source[i + width + 1] - blacklevel];

		switch (pix_fmt) {
			case V4L2_PIX_FMT_SBGGR8:
				quick_debayer_set_dst(&destination[j],
						      b2, b1, b0);
				break;
			case V4L2_PIX_FMT_SGBRG8:
				quick_debayer_set_dst(&destination[j],
						      b1, b2, b0);
				break;
			case V4L2_PIX_FMT_SGRBG8:
				quick_debayer_set_dst(&destination[j],
						      b1, b0, b2);
				break;
			case V4L2_PIX_FMT_SRGGB8:
				/* fall through */
			default:
				quick_debayer_set_dst(&destination[j],
						      b0, b1, b2);
				break;
		}
		j += 3;

		i = i + byteskip;
		row_left = row_left - byteskip;
		if(row_left < byteskip){
			i = i + row_left;
			row_left = width;
			i = i + width;
			i = i + (width * 2 * (skip-1));
		}
	} while (i < input_size);
}


// YUV 4:2:2 to RGB conversion
void quick_yuv2rgb(const uint8_t *source, uint8_t *destination,
		uint32_t pix_fmt, int width, int height, int skip)
{
	int stride = width * 2;
	int pixelsize = 4;
	int input_size = width * 2 * height;
	int i = 0, j = 0;
	int row_left = stride;
	uint8_t Y1, Y2, U, V;
	do {
		switch (pix_fmt) {
			case V4L2_PIX_FMT_UYVY:
				Y1 = source[i+1];
				Y2 = source[i+3];
				U = source[i];
				V = source[i+2];
				break;
			case V4L2_PIX_FMT_YUYV:
				Y1 = source[i];
				Y2 = source[i+2];
				U = source[i+1];
				V = source[i+3];
				break;
		}
		destination[j] = 1.164f * Y1 + 1.596f * (V - 128);
		destination[j+1] = 1.164f * Y1 - 0.813f * (V - 128) - 0.391f * (U - 128);
		destination[j+2] = 1.164f * Y1 + 2.018f * (U - 128);
		j += 3;
		destination[j] = 1.164f * Y2 + 1.596f * (V - 128);
		destination[j+1] = 1.164f * Y2 - 0.813f * (V - 128) - 0.391f * (U - 128);
		destination[j+2] = 1.164f * Y2 + 2.018f * (U - 128);
		j += 3;

		i += pixelsize * skip * 2;
		row_left -= (pixelsize * skip * 2);
		if(row_left < (pixelsize * skip * 2)){
			i = i + row_left;
			row_left = width;
			i = i + (stride * skip);
		}
	} while (i < input_size);
}