From d479dd1aab1c1cb907932c6595b0ef33523fc797 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=B6rg=20Frings-F=C3=BCrst?= Date: Fri, 6 Nov 2015 07:14:47 +0100 Subject: Imported Upstream version 1.8.3 --- tiff/html/man/TIFFcolor.3tiff.html | 975 ------------------------------------- 1 file changed, 975 deletions(-) delete mode 100755 tiff/html/man/TIFFcolor.3tiff.html (limited to 'tiff/html/man/TIFFcolor.3tiff.html') diff --git a/tiff/html/man/TIFFcolor.3tiff.html b/tiff/html/man/TIFFcolor.3tiff.html deleted file mode 100755 index edf423b..0000000 --- a/tiff/html/man/TIFFcolor.3tiff.html +++ /dev/null @@ -1,975 +0,0 @@ - - - - - - -COLOR - - - -

COLOR

-NAME
-SYNOPSIS
-DESCRIPTION
-SEE ALSO
- -
- -

NAME

- - - - - -
-

TIFFYCbCrToRGBInit, TIFFYCbCrtoRGB, TIFFCIELabToRGBInit, -TIFFCIELabToXYZ, TIFFXYZToRGB − color conversion -routines.

-
- -

SYNOPSIS

- - - - - -
-

#include <tiffio.h>

- -

int TIFFYCbCrToRGBInit(TIFFYCbCrToRGB -*ycbcr, float *luma, float -*refBlackWhite");"
-void TIFFYCbCrtoRGB(TIFFYCbCrToRGB *ycbcr, -uint32 Y, int32 Cb, int32 -Cr, uint32 *R, uint32 -*G, uint32 *B );

- -

int TIFFCIELabToRGBInit(TIFFCIELabToRGB -*cielab, TIFFDisplay *display, -float *refWhite);
-void TIFFCIELabToXYZ(TIFFCIELabToRGB *cielab, -uint32 L, int32 a, int32 -b, float *X, float *Y, -float *Z);
-void TIFFXYZToRGB(TIFFCIELabToRGB *cielab, -float X, float Y, float -Z",uint32*"R, -uint32 *G, uint32 *B);

-
- -

DESCRIPTION

- - - - - -
-

TIFF supports several color spaces for images stored in -that format. There is usually a problem of application to -handle the data properly and convert between different -colorspaces for displaying and printing purposes. To -simplify this task libtiff implements several color -conversion routines itself. In particular, these routines -used in TIFFRGBAImage(3TIFF) interface.

- -

TIFFYCbCrToRGBInit() used to initialize -YCbCr to RGB conversion state. Allocating and -freeing of the ycbcr structure belongs to programmer. -TIFFYCbCrToRGB defined in tiffio.h as

-
- - - - - -
-
typedef struct {                /* YCbCr->RGB support */
-        TIFFRGBValue* clamptab; /* range clamping table */
-
-
- - - - - -

int*

- - - - - - - - - - - - - - - - - - - - - - - -
- -

Cr_r_tab;
-int*

-		 -
- -

Cb_b_tab;
-int32*

-		 -
- -

Cr_g_tab;
-int32*

-		 -
- -

Cb_g_tab;

-		 -
- - - - - -
-

int32* Y_tab;
-} TIFFYCbCrToRGB;

- - - - - -
-

luma is a float array of three values representing -proportions of the red, green and blue in luminance, Y (see -section 21 of the TIFF 6.0 specification, where the YCbCr -images discussed). TIFFTAG_YCBCRCOEFFICIENTS holds -that values in TIFF file. refBlackWhite is a float -array of 6 values which specifies a pair of headroom and -footroom image data values (codes) for each image component -(see section 20 of the TIFF 6.0 specification where the -colorinmetry fields discussed). -TIFFTAG_REFERENCEBLACKWHITE is responsible for -storing these values in TIFF file. Following code snippet -should helps to understand the the technique:

-
- - - - - -
-
float *luma, *refBlackWhite;
-uint16 hs, vs;
-
-/* Initialize structures */
-ycbcr = (TIFFYCbCrToRGB*)
-
-
- - - - - - - - - - - - - - - -
- -

_TIFFmalloc(TIFFroundup(sizeof(TIFFYCbCrToRGB), -sizeof(long))

-
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+ 4*256*sizeof(TIFFRGBValue)

-
- -

+ 2*256*sizeof(int)

-
- -

+ 3*256*sizeof(int32));

-
- - - - - -
-

if (ycbcr == NULL) {
-TIFFError("YCbCr->RGB",

- - - - - - - -
- - -

"No space for YCbCr->RGB conversion -state");

-		 -
- - - - - -
-

exit(0);
-}

- -

TIFFGetFieldDefaulted(tif, TIFFTAG_YCBCRCOEFFICIENTS, -&luma);
-TIFFGetFieldDefaulted(tif, TIFFTAG_REFERENCEBLACKWHITE, -&refBlackWhite);
-if (TIFFYCbCrToRGBInit(ycbcr, luma, refBlackWhite) < -0)

- - - - - -
- -

exit(0);

-
- - - - - -
-

/* Start conversion */
-uint32 r, g, b;
-uint32 Y;
-int32 Cb, Cr;

- -

for each pixel in image

- - - - - -
- -

TIFFYCbCrtoRGB(img->ycbcr, Y, Cb, Cr, &r, &g, -&b);

-
- - - - - -
-

/* Free state structure */
-_TIFFfree(ycbcr);

- - - - - -
-

TIFFCIELabToRGBInit() initializes the CIE -L*a*b* 1976 to RGB conversion state. -TIFFCIELabToRGB defined as

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-
#define CIELABTORGB_TABLE_RANGE 1500
-
-
-
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- -

typedef struct {

-		 - - -

/* CIE Lab 1976->RGB support */

-		 -
- - -

int

-		 - -

range;

-		 - - -

/* Size of conversion table */

-		 -
- - -

float

-		 - -

rstep, gstep, bstep;

-		 -
- - -

float

-		 - -

X0, Y0, Z0;

-		 - -

/* Reference white point */

-		 -
- -

TIFFDisplay display;

-		 -
- - -

float

-		 - -

Yr2r[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yr -to r */

-		 -
- - -

float

-		 - -

Yg2g[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yg -to g */

-		 -
- - -

float

-		 - -

Yb2b[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yb -to b */

-		 -
- - - - - -
-

} TIFFCIELabToRGB;

- - - - - -
-

display is a display device description, declared -as

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-
typedef struct {
-
-
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- -

float d_mat[3][3]; /* XYZ -> luminance matrix */

-
- -

float d_YCR; /* Light o/p for reference white */

-
- -

float d_YCG;

-
- -

float d_YCB;

-
- -

uint32 d_Vrwr; /* Pixel values for ref. white */

-
- -

uint32 d_Vrwg;

-
- -

uint32 d_Vrwb;

-
- -

float d_Y0R; /* Residual light for black pixel */

-
- -

float d_Y0G;

-
- -

float d_Y0B;

-
- -

float d_gammaR; /* Gamma values for the three guns -*/

-
- -

float d_gammaG;

-
- -

float d_gammaB;

-
- - - - - -
-

} TIFFDisplay;

- - - - - -
-

For example, the one can use sRGB device, which has the -following parameters:

-
- - - - - -
-
TIFFDisplay display_sRGB = {
-
-
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- -

{ /* XYZ -> luminance matrix */

-		 -
- - -

{ 3.2410F, -1.5374F, -0.4986F },

-		 -
- - -

{ -0.9692F, 1.8760F, 0.0416F },

-		 -
- - -

{ 0.0556F, -0.2040F, 1.0570F }

-		 -
- -

},

-		 - -
- -

100.0F, 100.0F, 100.0F, /* Light o/p for reference white -*/

-		 -
- -

255, 255, 255, /* Pixel values for ref. white */

-		 -
- -

1.0F, 1.0F, 1.0F, /* Residual light o/p for black pixel -*/

-		 -
- -

2.4F, 2.4F, 2.4F, /* Gamma values for the three guns -*/

-		 -
- - - - - -
-

};

- - - - - -
-

refWhite is a color temperature of the reference -white. The TIFFTAG_WHITEPOINT contains the -chromaticity of the white point of the image from where the -reference white can be calculated using following -formulae:

-
- - - - - -
-

refWhite_Y = 100.0
-refWhite_X = whitePoint_x / whitePoint_y * refWhite_Y
-refWhite_Z = (1.0 - whitePoint_x - whitePoint_y) / -whitePoint_y * refWhite_X

- - - - - -
-

The conversion itself performed in two steps: at the -first one we will convert CIE L*a*b* 1976 to CIE -XYZ using TIFFCIELabToXYZ() routine, and at the -second step we will convert CIE XYZ to RGB -using TIFFXYZToRGB(). Look at the code sample -below:

-
- - - - - -
-
float   *whitePoint;
-float   refWhite[3];
-
-/* Initialize structures */
-img->cielab = (TIFFCIELabToRGB *)
-
-
- - - - - - -
- -

_TIFFmalloc(sizeof(TIFFCIELabToRGB));

-
- - - - - -
-

if (!cielab) {

- - - - - - - - - - - - - - - - - - - - -
- -

TIFFError("CIE L*a*b*->RGB",

-		 -
- - -

"No space for CIE L*a*b*->RGB conversion -state.");

-		 -
- -

exit(0);

-		 -
- - - - - -
-

}

- -

TIFFGetFieldDefaulted(tif, TIFFTAG_WHITEPOINT, -&whitePoint);
-refWhite[1] = 100.0F;
-refWhite[0] = whitePoint[0] / whitePoint[1] * -refWhite[1];
-refWhite[2] = (1.0F - whitePoint[0] - -whitePoint[1])

- - - - - -
- -

/ whitePoint[1] * refWhite[1];

-
- - - - - -
-

if (TIFFCIELabToRGBInit(cielab, &display_sRGB, -refWhite) < 0) {

- - - - - - - - - - - - - - - - - - - - - - - - - - -
- -

TIFFError("CIE L*a*b*->RGB",

-		 -
- - -

"Failed to initialize CIE L*a*b*->RGB conversion -state.");

-		 -
- -

_TIFFfree(cielab);

-		 -
- -

exit(0);

-		 -
- - - - - -
-

}

- -

/* Now we can start to convert */
-uint32 r, g, b;
-uint32 L;
-int32 a, b;
-float X, Y, Z;

- -

for each pixel in image

- - - - - - - - -
- -

TIFFCIELabToXYZ(cielab, L, a, b, &X, &Y, -&Z);

-
- -

TIFFXYZToRGB(cielab, X, Y, Z, &r, &g, -&b);

-
- - - - - -
-

/* Don’t forget to free the state structure */
-_TIFFfree(cielab);

- -

SEE ALSO

- - - - - -
-

TIFFRGBAImage(3TIFF) libtiff(3TIFF),

- -

Libtiff library home page: -http://www.remotesensing.org/libtiff/

-
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- - -- cgit v1.2.3