source-git / compat-libtiff3

Clone
Source Code
GIT

Blame html/man/TIFFcolor.3tiff.html

c8 c8s master
  1.   9085e20561efcff468cbcf9c074b55450fe749ca
  2.   html
  3.   man
  4.   TIFFcolor.3tiff.html
Blob History Raw
Packit 994f1a
Packit 994f1a
Packit 994f1a 
<html>
Packit 994f1a 
<head>
Packit 994f1a 
<meta name="generator" content="groff -Thtml, see www.gnu.org">
Packit 994f1a 
<meta name="Content-Style" content="text/css">
Packit 994f1a 
<title>COLOR</title>
Packit 994f1a 
</head>
Packit 994f1a 
<body>
Packit 994f1a
Packit 994f1a 
COLOR
Packit 994f1a 
NAME
Packit 994f1a 
SYNOPSIS
Packit 994f1a 
DESCRIPTION
Packit 994f1a 
SEE ALSO
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
NAME
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFYCbCrToRGBInit, TIFFYCbCrtoRGB, TIFFCIELabToRGBInit,
Packit 994f1a 
TIFFCIELabToXYZ, TIFFXYZToRGB − color conversion
Packit 994f1a 
routines.
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
SYNOPSIS
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
#include <tiffio.h>
Packit 994f1a
Packit 994f1a 
int TIFFYCbCrToRGBInit(TIFFYCbCrToRGB
Packit 994f1a 
*ycbcr, float *luma, float
Packit 994f1a 
*refBlackWhite");"
Packit 994f1a 
void TIFFYCbCrtoRGB(TIFFYCbCrToRGB *ycbcr,
Packit 994f1a 
uint32 Y, int32 Cb, int32
Packit 994f1a 
Cr, uint32 *R, uint32
Packit 994f1a 
*G, uint32 *B );
Packit 994f1a
Packit 994f1a 
int TIFFCIELabToRGBInit(TIFFCIELabToRGB
Packit 994f1a 
*cielab, TIFFDisplay *display,
Packit 994f1a 
float *refWhite);
Packit 994f1a 
void TIFFCIELabToXYZ(TIFFCIELabToRGB *cielab,
Packit 994f1a 
uint32 L, int32 a, int32
Packit 994f1a 
b, float *X, float *Y,
Packit 994f1a 
float *Z);
Packit 994f1a 
void TIFFXYZToRGB(TIFFCIELabToRGB *cielab,
Packit 994f1a 
float X, float Y, float
Packit 994f1a 
Z",uint32*"R,
Packit 994f1a 
uint32 *G, uint32 *B);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
DESCRIPTION
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFF supports several color spaces for images stored in
Packit 994f1a 
that format. There is usually a problem of application to
Packit 994f1a 
handle the data properly and convert between different
Packit 994f1a 
colorspaces for displaying and printing purposes. To
Packit 994f1a 
simplify this task libtiff implements several color
Packit 994f1a 
conversion routines itself. In particular, these routines
Packit 994f1a 
used in TIFFRGBAImage(3TIFF) interface.
Packit 994f1a
Packit 994f1a 
TIFFYCbCrToRGBInit() used to initialize
Packit 994f1a 
YCbCr to RGB conversion state. Allocating and
Packit 994f1a 
freeing of the ycbcr structure belongs to programmer.
Packit 994f1a 
TIFFYCbCrToRGB defined in tiffio.h as
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
typedef struct {                /* YCbCr->RGB support */
Packit 994f1a 
        TIFFRGBValue* clamptab; /* range clamping table */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="5" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a 
int*
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
Cr_r_tab;
Packit 994f1a 
int*
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
Cb_b_tab;
Packit 994f1a 
int32*
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
Cr_g_tab;
Packit 994f1a 
int32*
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
Cb_g_tab;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
int32* Y_tab;
Packit 994f1a 
} TIFFYCbCrToRGB;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
luma is a float array of three values representing
Packit 994f1a 
proportions of the red, green and blue in luminance, Y (see
Packit 994f1a 
section 21 of the TIFF 6.0 specification, where the YCbCr
Packit 994f1a 
images discussed). TIFFTAG_YCBCRCOEFFICIENTS holds
Packit 994f1a 
that values in TIFF file. refBlackWhite is a float
Packit 994f1a 
array of 6 values which specifies a pair of headroom and
Packit 994f1a 
footroom image data values (codes) for each image component
Packit 994f1a 
(see section 20 of the TIFF 6.0 specification where the
Packit 994f1a 
colorinmetry fields discussed).
Packit 994f1a 
TIFFTAG_REFERENCEBLACKWHITE is responsible for
Packit 994f1a 
storing these values in TIFF file. Following code snippet
Packit 994f1a 
should helps to understand the the technique:
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float *luma, *refBlackWhite;
Packit 994f1a 
uint16 hs, vs;
Packit 994f1a
Packit 994f1a 
/* Initialize structures */
Packit 994f1a 
ycbcr = (TIFFYCbCrToRGB*)
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
_TIFFmalloc(TIFFroundup(sizeof(TIFFYCbCrToRGB),
Packit 994f1a 
sizeof(long))
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
+ 4*256*sizeof(TIFFRGBValue)
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
+ 2*256*sizeof(int)
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
+ 3*256*sizeof(int32));
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
if (ycbcr == NULL) {
Packit 994f1a 
TIFFError("YCbCr->RGB",
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="4" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
"No space for YCbCr->RGB conversion
Packit 994f1a 
state");
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
exit(0);
Packit 994f1a 
}
Packit 994f1a
Packit 994f1a 
TIFFGetFieldDefaulted(tif, TIFFTAG_YCBCRCOEFFICIENTS,
Packit 994f1a 
&luma);
Packit 994f1a 
TIFFGetFieldDefaulted(tif, TIFFTAG_REFERENCEBLACKWHITE,
Packit 994f1a 
&refBlackWhite);
Packit 994f1a 
if (TIFFYCbCrToRGBInit(ycbcr, luma, refBlackWhite) <
Packit 994f1a 
0)
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
exit(0);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
/* Start conversion */
Packit 994f1a 
uint32 r, g, b;
Packit 994f1a 
uint32 Y;
Packit 994f1a 
int32 Cb, Cr;
Packit 994f1a
Packit 994f1a 
for each pixel in image
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFYCbCrtoRGB(img->ycbcr, Y, Cb, Cr, &r, &g,
Packit 994f1a 
&b);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
/* Free state structure */
Packit 994f1a 
_TIFFfree(ycbcr);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFCIELabToRGBInit() initializes the CIE
Packit 994f1a 
L*a*b* 1976 to RGB conversion state.
Packit 994f1a 
TIFFCIELabToRGB defined as
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
#define CIELABTORGB_TABLE_RANGE 1500
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="9" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
typedef struct {
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
/* CIE Lab 1976->RGB support */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
int
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
range;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
/* Size of conversion table */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
rstep, gstep, bstep;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
X0, Y0, Z0;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
/* Reference white point */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFDisplay display;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
Yr2r[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yr
Packit 994f1a 
to r */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
Yg2g[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yg
Packit 994f1a 
to g */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
Yb2b[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yb
Packit 994f1a 
to b */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
} TIFFCIELabToRGB;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
display is a display device description, declared
Packit 994f1a 
as
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
typedef struct {
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_mat[3][3]; /* XYZ -> luminance matrix */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_YCR; /* Light o/p for reference white */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_YCG;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_YCB;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
uint32 d_Vrwr; /* Pixel values for ref. white */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
uint32 d_Vrwg;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
uint32 d_Vrwb;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_Y0R; /* Residual light for black pixel */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_Y0G;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_Y0B;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_gammaR; /* Gamma values for the three guns
Packit 994f1a 
*/
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_gammaG;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float d_gammaB;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
} TIFFDisplay;
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
For example, the one can use sRGB device, which has the
Packit 994f1a 
following parameters:
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFDisplay display_sRGB = {
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="5" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
{ /* XYZ -> luminance matrix */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
{ 3.2410F, -1.5374F, -0.4986F },
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
{ -0.9692F, 1.8760F, 0.0416F },
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
{ 0.0556F, -0.2040F, 1.0570F }
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
},
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
100.0F, 100.0F, 100.0F, /* Light o/p for reference white
Packit 994f1a 
*/
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
255, 255, 255, /* Pixel values for ref. white */
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
1.0F, 1.0F, 1.0F, /* Residual light o/p for black pixel
Packit 994f1a 
*/
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
2.4F, 2.4F, 2.4F, /* Gamma values for the three guns
Packit 994f1a 
*/
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
};
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
refWhite is a color temperature of the reference
Packit 994f1a 
white. The TIFFTAG_WHITEPOINT contains the
Packit 994f1a 
chromaticity of the white point of the image from where the
Packit 994f1a 
reference white can be calculated using following
Packit 994f1a 
formulae:
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
refWhite_Y = 100.0
Packit 994f1a 
refWhite_X = whitePoint_x / whitePoint_y * refWhite_Y
Packit 994f1a 
refWhite_Z = (1.0 - whitePoint_x - whitePoint_y) /
Packit 994f1a 
whitePoint_y * refWhite_X
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
The conversion itself performed in two steps: at the
Packit 994f1a 
first one we will convert CIE L*a*b* 1976 to CIE
Packit 994f1a 
XYZ using TIFFCIELabToXYZ() routine, and at the
Packit 994f1a 
second step we will convert CIE XYZ to RGB
Packit 994f1a 
using TIFFXYZToRGB(). Look at the code sample
Packit 994f1a 
below:
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
float   *whitePoint;
Packit 994f1a 
float   refWhite[3];
Packit 994f1a
Packit 994f1a 
/* Initialize structures */
Packit 994f1a 
img->cielab = (TIFFCIELabToRGB *)
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
_TIFFmalloc(sizeof(TIFFCIELabToRGB));
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
if (!cielab) {
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="5" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFError("CIE L*a*b*->RGB",
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
"No space for CIE L*a*b*->RGB conversion
Packit 994f1a 
state.");
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
exit(0);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
}
Packit 994f1a
Packit 994f1a 
TIFFGetFieldDefaulted(tif, TIFFTAG_WHITEPOINT,
Packit 994f1a 
&whitePoint);
Packit 994f1a 
refWhite[1] = 100.0F;
Packit 994f1a 
refWhite[0] = whitePoint[0] / whitePoint[1] *
Packit 994f1a 
refWhite[1];
Packit 994f1a 
refWhite[2] = (1.0F - whitePoint[0] -
Packit 994f1a 
whitePoint[1])
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
/ whitePoint[1] * refWhite[1];
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
if (TIFFCIELabToRGBInit(cielab, &display_sRGB,
Packit 994f1a 
refWhite) < 0) {
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="5" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFError("CIE L*a*b*->RGB",
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
"Failed to initialize CIE L*a*b*->RGB conversion
Packit 994f1a 
state.");
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
_TIFFfree(cielab);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
exit(0);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
}
Packit 994f1a
Packit 994f1a 
/* Now we can start to convert */
Packit 994f1a 
uint32 r, g, b;
Packit 994f1a 
uint32 L;
Packit 994f1a 
int32 a, b;
Packit 994f1a 
float X, Y, Z;
Packit 994f1a
Packit 994f1a 
for each pixel in image
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFCIELabToXYZ(cielab, L, a, b, &X, &Y,
Packit 994f1a 
&Z);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFXYZToRGB(cielab, X, Y, Z, &r, &g,
Packit 994f1a 
&b);
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
/* Don’t forget to free the state structure */
Packit 994f1a 
_TIFFfree(cielab);
Packit 994f1a
Packit 994f1a
Packit 994f1a 
SEE ALSO
Packit 994f1a
Packit 994f1a
Packit 994f1a 
       cols="2" cellspacing="0" cellpadding="0">
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
TIFFRGBAImage(3TIFF) libtiff(3TIFF),
Packit 994f1a
Packit 994f1a 
Libtiff library home page:
Packit 994f1a 
http://www.remotesensing.org/libtiff/
Packit 994f1a
Packit 994f1a
Packit 994f1a
Packit 994f1a 
</body>
Packit 994f1a 
</html>

Powered by Pagure 5.14.1

SSH Hostkey/Fingerprint | Documentation