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get ready for a 16-bit path in srgb/xyz

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This commit is contained in:
John Cupitt 2012-11-05 22:11:15 +00:00
parent c17cd32ea1
commit e0b3b4157f
4 changed files with 82 additions and 61 deletions
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135
libvips/colour/LabQ2sRGB.c
View File

@ -53,23 +53,46 @@
#include "colour.h"
/* The number of elements in the linear float -> sRGB table.
*/
#define TABLE_SIZE (256)
typedef VipsColourCode VipsLabQ2sRGB;
typedef VipsColourCodeClass VipsLabQ2sRGBClass;
G_DEFINE_TYPE( VipsLabQ2sRGB, vips_LabQ2sRGB, VIPS_TYPE_COLOUR_CODE );
/* linear -> sRGB lut. There's an extra element at the end to let us do a +1
* for interpolation.
/* 8-bit linear -> sRGB lut.
*
* There's an extra element at the end to let us do a +1 for interpolation.
*/
static int vips_Y2v[TABLE_SIZE + 1];
static int vips_Y2v_8[256 + 1];
/* sRGB -> linear lut.
/* 8-bit sRGB -> linear lut.
*/
static float vips_v2Y[256];
static float vips_v2Y_8[256];
/* 16-bit linear -> sRGB lut.
*
* There's an extra element at the end to let us do a +1 for interpolation.
*/
static int vips_16_Y2v[65536 + 1];
/* 16-bit sRGB -> linear lut.
*/
static float vips_16_v2Y[65536];
/* linear RGB -> XYZ matrix.
*/
static float vips_mat_RGB2XYZ[3][3] = {
{ 0.4124, 0.3576, 0.18056 },
{ 0.2126, 0.7152, 0.0722 },
{ 0.0193, 0.1192, 0.9505 }
};
/* XYZ -> linear RGB matrix.
*/
static float vips_mat_XYZ2RGB[3][3] = {
{ 3.2406, -1.5372, -0.4986 },
{ -0.9689, 1.8758, 0.0415, },
{ 0.0557, -0.2040, 1.0570 }
};
/* Do our own indexing of the arrays below to make sure we get efficient mults.
*/
@ -84,12 +107,12 @@ static VipsPel vips_blue[64 * 64 * 64];
/* Create the sRGB linear and unlinear luts.
*/
static void *
calcul_tables( void *client )
calcul_tables_8( void *client )
{
int i;
for( i = 0; i < TABLE_SIZE; i++ ) {
float f = (float) i / (TABLE_SIZE - 1);
for( i = 0; i < 256; i++ ) {
float f = (float) i / (256 - 1);
float v;
if( f <= 0.0031308 )
@ -97,28 +120,28 @@ calcul_tables( void *client )
else
v = (1.0 + 0.055) * pow( f, 1.0 / 2.4 ) - 0.055;
vips_Y2v[i] = 255.0 * v;
vips_Y2v_8[i] = 255.0 * v;
}
/* Copy the final element. This is used in the piecewise linear
* interpolator below.
*/
vips_Y2v[TABLE_SIZE] = vips_Y2v[TABLE_SIZE - 1];
vips_Y2v_8[256] = vips_Y2v_8[256 - 1];
for( i = 0; i < 256; i++ ) {
float f = i / 255.0;
if( f <= 0.04045 )
vips_v2Y[i] = f / 12.92;
vips_v2Y_8[i] = f / 12.92;
else
vips_v2Y[i] = pow( (f + 0.055) / (1 + 0.055), 2.4 );
vips_v2Y_8[i] = pow( (f + 0.055) / (1 + 0.055), 2.4 );
}
return( NULL );
}
static void
vips_col_make_tables_RGB( void )
vips_col_make_tables_RGB_8( void )
{
static gboolean made_tables = FALSE;
@ -128,7 +151,7 @@ vips_col_make_tables_RGB( void )
if( !made_tables ) {
static GOnce once = G_ONCE_INIT;
(void) g_once( &once, calcul_tables, NULL );
(void) g_once( &once, calcul_tables_8, NULL );
made_tables = TRUE;
}
}
@ -137,35 +160,36 @@ vips_col_make_tables_RGB( void )
* lookup tables and calculates X, Y, Z.
*/
int
vips_col_sRGB2XYZ( int r, int g, int b, float *X, float *Y, float *Z )
vips_col_sRGB2XYZ_8( int r, int g, int b, float *X, float *Y, float *Z )
{
/* linear RGB -> XYZ matrix.
*/
static float mat[3][3] = {
{ 0.4124, 0.3576, 0.18056 },
{ 0.2126, 0.7152, 0.0722 },
{ 0.0193, 0.1192, 0.9505 }
};
float *lut = vips_v2Y_8;
float Yr, Yg, Yb;
int i;
vips_col_make_tables_RGB();
vips_col_make_tables_RGB_8();
i = VIPS_CLIP( 0, r, 255 );
Yr = vips_v2Y[i];
Yr = lut[i];
i = VIPS_CLIP( 0, g, 255 );
Yg = vips_v2Y[i];
Yg = lut[i];
i = VIPS_CLIP( 0, b, 255 );
Yb = vips_v2Y[i];
Yb = lut[i];
/* The matrix already includes D65 channel weighting.
*/
*X = VIPS_D65_Y0 * (mat[0][0] * Yr + mat[0][1] * Yg + mat[0][2] * Yb);
*Y = VIPS_D65_Y0 * (mat[1][0] * Yr + mat[1][1] * Yg + mat[1][2] * Yb);
*Z = VIPS_D65_Y0 * (mat[2][0] * Yr + mat[2][1] * Yg + mat[2][2] * Yb);
*X = vips_mat_RGB2XYZ[0][0] * Yr +
vips_mat_RGB2XYZ[0][1] * Yg + vips_mat_RGB2XYZ[0][2] * Yb;
*Y = vips_mat_RGB2XYZ[1][0] * Yr +
vips_mat_RGB2XYZ[1][1] * Yg + vips_mat_RGB2XYZ[1][2] * Yb;
*Z = vips_mat_RGB2XYZ[2][0] * Yr +
vips_mat_RGB2XYZ[2][1] * Yg + vips_mat_RGB2XYZ[2][2] * Yb;
*X *= VIPS_D65_Y0;
*Y *= VIPS_D65_Y0;
*Z *= VIPS_D65_Y0;
return( 0 );
}
@ -174,17 +198,11 @@ vips_col_sRGB2XYZ( int r, int g, int b, float *X, float *Y, float *Z )
* contain an approximation of the right colour.
*/
int
vips_col_XYZ2sRGB( float X, float Y, float Z,
vips_col_XYZ2sRGB_8( float X, float Y, float Z,
int *r_ret, int *g_ret, int *b_ret,
int *or_ret )
{
/* XYZ -> linear RGB matrix.
*/
static float mat[3][3] = {
{ 3.2406, -1.5372, -0.4986 },
{ -0.9689, 1.8758, 0.0415, },
{ 0.0557, -0.2040, 1.0570 }
};
int *lut = vips_Y2v_8;
int or;
@ -194,7 +212,7 @@ vips_col_XYZ2sRGB( float X, float Y, float Z,
float v;
int r, g, b;
vips_col_make_tables_RGB();
vips_col_make_tables_RGB_8();
/* The matrix already includes D65 channel weighting, just change from
* 0 - 100 to 0 - 1.
@ -205,9 +223,12 @@ vips_col_XYZ2sRGB( float X, float Y, float Z,
/* Multiply through the matrix to get luminosity values.
*/
Yr = mat[0][0] * X + mat[0][1] * Y + mat[0][2] * Z;
Yg = mat[1][0] * X + mat[1][1] * Y + mat[1][2] * Z;
Yb = mat[2][0] * X + mat[2][1] * Y + mat[2][2] * Z;
Yr = vips_mat_XYZ2RGB[0][0] * X +
vips_mat_XYZ2RGB[0][1] * Y + vips_mat_XYZ2RGB[0][2] * Z;
Yg = vips_mat_XYZ2RGB[1][0] * X +
vips_mat_XYZ2RGB[1][1] * Y + vips_mat_XYZ2RGB[1][2] * Z;
Yb = vips_mat_XYZ2RGB[2][0] * X +
vips_mat_XYZ2RGB[2][1] * Y + vips_mat_XYZ2RGB[2][2] * Z;
/* Clip range, set the out-of-range flag.
*/
@ -222,30 +243,30 @@ vips_col_XYZ2sRGB( float X, float Y, float Z,
} \
}
/* Work out colour value (0-Vrw) to feed the tube to get that
* luminosity.
/* Look up with a float index: interpolate between the nearest two
* points.
*
* The +1 on the index is safe, see above.
*/
or = 0;
Yf = Yr * (TABLE_SIZE - 1);
CLIP( 0, Yf, TABLE_SIZE - 1);
Yf = Yr * (256 - 1);
CLIP( 0, Yf, 256 - 1);
Yi = (int) Yf;
v = vips_Y2v[Yi] + (vips_Y2v[Yi + 1] - vips_Y2v[Yi]) * (Yf - Yi);
v = lut[Yi] + (lut[Yi + 1] - lut[Yi]) * (Yf - Yi);
r = VIPS_RINT( v );
Yf = Yg * (TABLE_SIZE - 1);
CLIP( 0, Yf, TABLE_SIZE - 1);
Yf = Yg * (256 - 1);
CLIP( 0, Yf, 256 - 1);
Yi = (int) Yf;
v = vips_Y2v[Yi] + (vips_Y2v[Yi + 1] - vips_Y2v[Yi]) * (Yf - Yi);
v = lut[Yi] + (lut[Yi + 1] - lut[Yi]) * (Yf - Yi);
g = VIPS_RINT( v );
Yf = Yb * (TABLE_SIZE - 1);
CLIP( 0, Yf, TABLE_SIZE - 1);
Yf = Yb * (256 - 1);
CLIP( 0, Yf, 256 - 1);
Yi = (int) Yf;
v = vips_Y2v[Yi] + (vips_Y2v[Yi + 1] - vips_Y2v[Yi]) * (Yf - Yi);
v = lut[Yi] + (lut[Yi + 1] - lut[Yi]) * (Yf - Yi);
b = VIPS_RINT( v );
*r_ret = r;
@ -278,7 +299,7 @@ build_tables( void *client )
int oflow;
vips_col_Lab2XYZ( L, A, B, &X, &Y, &Z );
vips_col_XYZ2sRGB( X, Y, Z,
vips_col_XYZ2sRGB_8( X, Y, Z,
&rb, &gb, &bb, &oflow );
t = INDEX( l, a, b );

2
libvips/colour/XYZ2sRGB.c
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@ -84,7 +84,7 @@ vips_XYZ2sRGB_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
int r, g, b;
int or;
vips_col_XYZ2sRGB( X, Y, Z, &r, &g, &b, &or );
vips_col_XYZ2sRGB_8( X, Y, Z, &r, &g, &b, &or );
p += 3;

2
libvips/colour/sRGB2XYZ.c
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@ -72,7 +72,7 @@ vips_sRGB2XYZ_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
p += 3;
vips_col_sRGB2XYZ( r, g, b, &X, &Y, &Z );
vips_col_sRGB2XYZ_8( r, g, b, &X, &Y, &Z );
q[0] = X;
q[1] = Y;

4
libvips/include/vips/colour.h
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@ -193,10 +193,10 @@ float vips_col_Lcmc2L( float Lcmc );
float vips_col_Ccmc2C( float Ccmc );
float vips_col_Chcmc2h( float C, float hcmc );
int vips_col_XYZ2sRGB( float X, float Y, float Z,
int vips_col_XYZ2sRGB_8( float X, float Y, float Z,
int *r_ret, int *g_ret, int *b_ret,
int *or_ret );
int vips_col_sRGB2XYZ( int r, int g, int b, float *X, float *Y, float *Z );
int vips_col_sRGB2XYZ_8( int r, int g, int b, float *X, float *Y, float *Z );
float vips_pythagoras( float L1, float a1, float b1,
float L2, float a2, float b2 );