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#include "vl_csc.h"
#include <util/u_math.h>
#include <util/u_debug.h>
/*
* Color space conversion formulas
*
* To convert YCbCr to RGB,
* vec4 ycbcr, rgb
* mat44 csc
* rgb = csc * ycbcr
*
* To calculate the color space conversion matrix csc with ProcAmp adjustments,
* mat44 csc, cstd, procamp, bias
* csc = cstd * (procamp * bias)
*
* Where cstd is a matrix corresponding to one of the color standards (BT.601, BT.709, etc)
* adjusted for the kind of YCbCr -> RGB mapping wanted (1:1, full),
* bias is a matrix corresponding to the kind of YCbCr -> RGB mapping wanted (1:1, full)
*
* To calculate procamp,
* mat44 procamp, hue, saturation, brightness, contrast
* procamp = brightness * (saturation * (contrast * hue))
* Alternatively,
* procamp = saturation * (brightness * (contrast * hue))
*
* contrast
* [ c, 0, 0, 0]
* [ 0, c, 0, 0]
* [ 0, 0, c, 0]
* [ 0, 0, 0, 1]
*
* brightness
* [ 1, 0, 0, b]
* [ 0, 1, 0, 0]
* [ 0, 0, 1, 0]
* [ 0, 0, 0, 1]
*
* saturation
* [ 1, 0, 0, 0]
* [ 0, s, 0, 0]
* [ 0, 0, s, 0]
* [ 0, 0, 0, 1]
*
* hue
* [ 1, 0, 0, 0]
* [ 0, cos(h), sin(h), 0]
* [ 0, -sin(h), cos(h), 0]
* [ 0, 0, 0, 1]
*
* procamp
* [ c, 0, 0, b]
* [ 0, c*s*cos(h), c*s*sin(h), 0]
* [ 0, -c*s*sin(h), c*s*cos(h), 0]
* [ 0, 0, 0, 1]
*
* bias
* [ 1, 0, 0, ybias]
* [ 0, 1, 0, cbbias]
* [ 0, 0, 1, crbias]
* [ 0, 0, 0, 1]
*
* csc
* [ c*cstd[ 0], c*cstd[ 1]*s*cos(h) - c*cstd[ 2]*s*sin(h), c*cstd[ 2]*s*cos(h) + c*cstd[ 1]*s*sin(h), cstd[ 3] + cstd[ 0]*(b + c*ybias) + cstd[ 1]*(c*cbbias*s*cos(h) + c*crbias*s*sin(h)) + cstd[ 2]*(c*crbias*s*cos(h) - c*cbbias*s*sin(h))]
* [ c*cstd[ 4], c*cstd[ 5]*s*cos(h) - c*cstd[ 6]*s*sin(h), c*cstd[ 6]*s*cos(h) + c*cstd[ 5]*s*sin(h), cstd[ 7] + cstd[ 4]*(b + c*ybias) + cstd[ 5]*(c*cbbias*s*cos(h) + c*crbias*s*sin(h)) + cstd[ 6]*(c*crbias*s*cos(h) - c*cbbias*s*sin(h))]
* [ c*cstd[ 8], c*cstd[ 9]*s*cos(h) - c*cstd[10]*s*sin(h), c*cstd[10]*s*cos(h) + c*cstd[ 9]*s*sin(h), cstd[11] + cstd[ 8]*(b + c*ybias) + cstd[ 9]*(c*cbbias*s*cos(h) + c*crbias*s*sin(h)) + cstd[10]*(c*crbias*s*cos(h) - c*cbbias*s*sin(h))]
* [ c*cstd[12], c*cstd[13]*s*cos(h) - c*cstd[14]*s*sin(h), c*cstd[14]*s*cos(h) + c*cstd[13]*s*sin(h), cstd[15] + cstd[12]*(b + c*ybias) + cstd[13]*(c*cbbias*s*cos(h) + c*crbias*s*sin(h)) + cstd[14]*(c*crbias*s*cos(h) - c*cbbias*s*sin(h))]
*/
/*
* Converts ITU-R BT.601 YCbCr pixels to RGB pixels where:
* Y is in [16,235], Cb and Cr are in [16,240]
* R, G, and B are in [16,235]
*/
static const float bt_601[16] =
{
1.0f, 0.0f, 1.371f, 0.0f,
1.0f, -0.336f, -0.698f, 0.0f,
1.0f, 1.732f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f
};
/*
* Converts ITU-R BT.601 YCbCr pixels to RGB pixels where:
* Y is in [16,235], Cb and Cr are in [16,240]
* R, G, and B are in [0,255]
*/
static const float bt_601_full[16] =
{
1.164f, 0.0f, 1.596f, 0.0f,
1.164f, -0.391f, -0.813f, 0.0f,
1.164f, 2.018f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f
};
/*
* Converts ITU-R BT.709 YCbCr pixels to RGB pixels where:
* Y is in [16,235], Cb and Cr are in [16,240]
* R, G, and B are in [16,235]
*/
static const float bt_709[16] =
{
1.0f, 0.0f, 1.540f, 0.0f,
1.0f, -0.183f, -0.459f, 0.0f,
1.0f, 1.816f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f
};
/*
* Converts ITU-R BT.709 YCbCr pixels to RGB pixels where:
* Y is in [16,235], Cb and Cr are in [16,240]
* R, G, and B are in [0,255]
*/
static const float bt_709_full[16] =
{
1.164f, 0.0f, 1.793f, 0.0f,
1.164f, -0.213f, -0.534f, 0.0f,
1.164f, 2.115f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f
};
static const float identity[16] =
{
1.0f, 0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f, 0.0f,
0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f
};
void vl_csc_get_matrix(enum VL_CSC_COLOR_STANDARD cs,
struct vl_procamp *procamp,
bool full_range,
float *matrix)
{
float ybias = full_range ? -16.0f/255.0f : 0.0f;
float cbbias = -128.0f/255.0f;
float crbias = -128.0f/255.0f;
float c = procamp ? procamp->contrast : 1.0f;
float s = procamp ? procamp->saturation : 1.0f;
float b = procamp ? procamp->brightness : 0.0f;
float h = procamp ? procamp->hue : 0.0f;
const float *cstd;
assert(matrix);
switch (cs) {
case VL_CSC_COLOR_STANDARD_BT_601:
cstd = full_range ? &bt_601_full[0] : &bt_601[0];
break;
case VL_CSC_COLOR_STANDARD_BT_709:
cstd = full_range ? &bt_709_full[0] : &bt_709[0];
break;
case VL_CSC_COLOR_STANDARD_IDENTITY:
default:
assert(cs == VL_CSC_COLOR_STANDARD_IDENTITY);
memcpy(matrix, &identity[0], sizeof(float) * 16);
return;
}
matrix[ 0] = c*cstd[ 0];
matrix[ 1] = c*cstd[ 1]*s*cosf(h) - c*cstd[ 2]*s*sinf(h);
matrix[ 2] = c*cstd[ 2]*s*cosf(h) + c*cstd[ 1]*s*sinf(h);
matrix[ 3] = cstd[ 3] + cstd[ 0]*(b + c*ybias) + cstd[ 1]*(c*cbbias*s*cosf(h) + c*crbias*s*sinf(h)) + cstd[ 2]*(c*crbias*s*cosf(h) - c*cbbias*s*sinf(h));
matrix[ 4] = c*cstd[ 4];
matrix[ 5] = c*cstd[ 5]*s*cosf(h) - c*cstd[ 6]*s*sinf(h);
matrix[ 6] = c*cstd[ 6]*s*cosf(h) + c*cstd[ 5]*s*sinf(h);
matrix[ 7] = cstd[ 7] + cstd[ 4]*(b + c*ybias) + cstd[ 5]*(c*cbbias*s*cosf(h) + c*crbias*s*sinf(h)) + cstd[ 6]*(c*crbias*s*cosf(h) - c*cbbias*s*sinf(h));
matrix[ 8] = c*cstd[ 8];
matrix[ 9] = c*cstd[ 9]*s*cosf(h) - c*cstd[10]*s*sinf(h);
matrix[10] = c*cstd[10]*s*cosf(h) + c*cstd[ 9]*s*sinf(h);
matrix[11] = cstd[11] + cstd[ 8]*(b + c*ybias) + cstd[ 9]*(c*cbbias*s*cosf(h) + c*crbias*s*sinf(h)) + cstd[10]*(c*crbias*s*cosf(h) - c*cbbias*s*sinf(h));
matrix[12] = c*cstd[12];
matrix[13] = c*cstd[13]*s*cos(h) - c*cstd[14]*s*sin(h);
matrix[14] = c*cstd[14]*s*cos(h) + c*cstd[13]*s*sin(h);
matrix[15] = cstd[15] + cstd[12]*(b + c*ybias) + cstd[13]*(c*cbbias*s*cos(h) + c*crbias*s*sin(h)) + cstd[14]*(c*crbias*s*cos(h) - c*cbbias*s*sin(h));
}
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