cheng/libtiff
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
20dc498028
libtiff/html/man/TIFFcolor.3tiff.html
Andrey Kiselev f14d1a5636 All makefile templates regenerated.
2007-06-27 12:03:37 +00:00

976 lines
22 KiB
HTML
Raw Blame History

<!-- Creator : groff version 1.18.1 -->
<!-- CreationDate: Sat Feb 24 18:37:16 2007 -->
<html>
<head>
<meta name="generator" content="groff -Thtml, see www.gnu.org">
<meta name="Content-Style" content="text/css">
<title>COLOR</title>
</head>
<body>
<h1 align=center>COLOR</h1>
<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<hr>
<a name="NAME"></a>
<h2>NAME</h2>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p>TIFFYCbCrToRGBInit, TIFFYCbCrtoRGB, TIFFCIELabToRGBInit,
TIFFCIELabToXYZ, TIFFXYZToRGB &minus; color conversion
routines.</p>
</td>
</table>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p><b>#include &lt;tiffio.h&gt;</b></p>
<!-- INDENTATION -->
<p><b>int TIFFYCbCrToRGBInit(TIFFYCbCrToRGB
*</b><i>ycbcr</i><b>, float *</b><i>luma</i><b>, float
*</b><i>refBlackWhite&quot;</i><b>);&quot;<br>
void TIFFYCbCrtoRGB(TIFFYCbCrToRGB *</b><i>ycbcr</i><b>,
uint32</b> <i>Y</i><b>, int32</b> <i>Cb</i><b>, int32</b>
<i>Cr</i><b>, uint32 *</b><i>R</i><b>, uint32
*</b><i>G</i><b>, uint32 *</b><i>B</i> <b>);</b></p>
<!-- INDENTATION -->
<p><b>int TIFFCIELabToRGBInit(TIFFCIELabToRGB
*</b><i>cielab</i><b>, TIFFDisplay *</b><i>display</i><b>,
float *</b><i>refWhite</i><b>);<br>
void TIFFCIELabToXYZ(TIFFCIELabToRGB *</b><i>cielab</i><b>,
uint32</b> <i>L</i><b>, int32</b> <i>a</i><b>, int32</b>
<i>b</i><b>, float *</b><i>X</i><b>, float *</b><i>Y</i><b>,
float *</b><i>Z</i><b>);<br>
void TIFFXYZToRGB(TIFFCIELabToRGB *</b><i>cielab</i><b>,
float</b> <i>X</i><b>, float</b> <i>Y</i><b>, float</b>
<i>Z&quot;</i><b>,</b><i>uint32</i><b>*&quot;</b><i>R</i><b>,
uint32 *</b><i>G</i><b>, uint32 *</b><i>B</i><b>);</b></p>
</td>
</table>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p>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 <b>TIFFRGBAImage(3TIFF)</b> interface.</p>
<!-- INDENTATION -->
<p><b>TIFFYCbCrToRGBInit()</b> used to initialize
<i>YCbCr</i> to <i>RGB</i> conversion state. Allocating and
freeing of the <i>ycbcr</i> structure belongs to programmer.
<i>TIFFYCbCrToRGB</i> defined in <b>tiffio.h</b> as</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<pre>typedef struct { /* YCbCr-&gt;RGB support */
TIFFRGBValue* clamptab; /* range clamping table */
</pre>
</td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="5" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<p>int*</p>
<td width="28%"></td>
<td width="-3%"></td>
<td width="12%"></td>
<td width="6%">
<p>Cr_r_tab;<br>
int*</p>
</td>
<td width="56%">
</td>
<tr valign="top" align="left">
<td width="28%"></td>
<td width="-3%"></td>
<td width="12%"></td>
<td width="6%">
<p>Cb_b_tab;<br>
int32*</p>
</td>
<td width="56%">
</td>
<tr valign="top" align="left">
<td width="28%"></td>
<td width="-3%"></td>
<td width="12%"></td>
<td width="6%">
<p>Cr_g_tab;<br>
int32*</p>
</td>
<td width="56%">
</td>
<tr valign="top" align="left">
<td width="28%"></td>
<td width="-3%"></td>
<td width="12%"></td>
<td width="6%">
<p>Cb_g_tab;</p>
</td>
<td width="56%">
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>int32* Y_tab;<br>
} TIFFYCbCrToRGB;</p></td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p><i>luma</i> 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). <i>TIFFTAG_YCBCRCOEFFICIENTS</i> holds
that values in TIFF file. <i>refBlackWhite</i> 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).
<i>TIFFTAG_REFERENCEBLACKWHITE</i> is responsible for
storing these values in TIFF file. Following code snippet
should helps to understand the the technique:</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<pre>float *luma, *refBlackWhite;
uint16 hs, vs;
/* Initialize structures */
ycbcr = (TIFFYCbCrToRGB*)
</pre>
</td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>_TIFFmalloc(TIFFroundup(sizeof(TIFFYCbCrToRGB),
sizeof(long))</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>+ 4*256*sizeof(TIFFRGBValue)</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>+ 2*256*sizeof(int)</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>+ 3*256*sizeof(int32));</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>if (ycbcr == NULL) {<br>
TIFFError(&quot;YCbCr-&gt;RGB&quot;,</p></td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="4" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="6%">
</td>
<td width="6%">
<p>&quot;No space for YCbCr-&gt;RGB conversion
state&quot;);</p>
</td>
<td width="62%">
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>exit(0);<br>
}</p>
<!-- INDENTATION -->
<p>TIFFGetFieldDefaulted(tif, TIFFTAG_YCBCRCOEFFICIENTS,
&amp;luma);<br>
TIFFGetFieldDefaulted(tif, TIFFTAG_REFERENCEBLACKWHITE,
&amp;refBlackWhite);<br>
if (TIFFYCbCrToRGBInit(ycbcr, luma, refBlackWhite) &lt;
0)</p></td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>exit(0);</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>/* Start conversion */<br>
uint32 r, g, b;<br>
uint32 Y;<br>
int32 Cb, Cr;</p>
<!-- INDENTATION -->
<p>for each pixel in image</p></td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>TIFFYCbCrtoRGB(img-&gt;ycbcr, Y, Cb, Cr, &amp;r, &amp;g,
&amp;b);</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>/* Free state structure */<br>
_TIFFfree(ycbcr);</p></td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p><b>TIFFCIELabToRGBInit()</b> initializes the <i>CIE
L*a*b* 1976</i> to <i>RGB</i> conversion state.
<b>TIFFCIELabToRGB</b> defined as</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<pre>#define CIELABTORGB_TABLE_RANGE 1500
</pre>
</td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="9" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="6%">
<p>typedef struct {</p>
</td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%">
</td>
<td width="6%">
<p>/* CIE Lab 1976-&gt;RGB support */</p>
</td>
<td width="6%"></td>
<td width="37%">
</td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="6%">
</td>
<td width="6%">
<p>int</p>
</td>
<td width="6%">
<p>range;</p>
</td>
<td width="6%"></td>
<td width="6%">
</td>
<td width="6%">
<p>/* Size of conversion table */</p>
</td>
<td width="6%"></td>
<td width="37%">
</td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="6%">
</td>
<td width="6%">
<p>float</p>
</td>
<td width="6%"></td>
<td width="6%">
<p>rstep, gstep, bstep;</p>
</td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%"></td>
<td width="37%">
</td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="6%">
</td>
<td width="6%">
<p>float</p>
</td>
<td width="6%"></td>
<td width="6%">
<p>X0, Y0, Z0;</p>
</td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%">
<p>/* Reference white point */</p>
</td>
<td width="37%">
</td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="6%"></td>
<td width="6%">
<p>TIFFDisplay display;</p>
</td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%"></td>
<td width="37%">
</td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="6%">
</td>
<td width="6%">
<p>float</p>
</td>
<td width="6%"></td>
<td width="6%">
<p>Yr2r[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yr
to r */</p>
</td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%"></td>
<td width="37%">
</td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="6%">
</td>
<td width="6%">
<p>float</p>
</td>
<td width="6%"></td>
<td width="6%">
<p>Yg2g[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yg
to g */</p>
</td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%"></td>
<td width="37%">
</td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="6%">
</td>
<td width="6%">
<p>float</p>
</td>
<td width="6%"></td>
<td width="6%">
<p>Yb2b[CIELABTORGB_TABLE_RANGE + 1]; /* Conversion of Yb
to b */</p>
</td>
<td width="6%"></td>
<td width="6%"></td>
<td width="6%"></td>
<td width="37%">
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>} TIFFCIELabToRGB;</p></td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p><i>display</i> is a display device description, declared
as</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<pre>typedef struct {
</pre>
</td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_mat[3][3]; /* XYZ -&gt; luminance matrix */</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_YCR; /* Light o/p for reference white */</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_YCG;</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_YCB;</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>uint32 d_Vrwr; /* Pixel values for ref. white */</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>uint32 d_Vrwg;</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>uint32 d_Vrwb;</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_Y0R; /* Residual light for black pixel */</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_Y0G;</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_Y0B;</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_gammaR; /* Gamma values for the three guns
*/</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_gammaG;</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>float d_gammaB;</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>} TIFFDisplay;</p></td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p>For example, the one can use sRGB device, which has the
following parameters:</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<pre>TIFFDisplay display_sRGB = {
</pre>
</td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="5" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>{ /* XYZ -&gt; luminance matrix */</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
</td>
<td width="6%">
<p>{ 3.2410F, -1.5374F, -0.4986F },</p>
</td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
</td>
<td width="6%">
<p>{ -0.9692F, 1.8760F, 0.0416F },</p>
</td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
</td>
<td width="6%">
<p>{ 0.0556F, -0.2040F, 1.0570F }</p>
</td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>},</p>
</td>
<td width="6%">
</td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>100.0F, 100.0F, 100.0F, /* Light o/p for reference white
*/</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>255, 255, 255, /* Pixel values for ref. white */</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>1.0F, 1.0F, 1.0F, /* Residual light o/p for black pixel
*/</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>2.4F, 2.4F, 2.4F, /* Gamma values for the three guns
*/</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>};</p></td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p><i>refWhite</i> is a color temperature of the reference
white. The <i>TIFFTAG_WHITEPOINT</i> contains the
chromaticity of the white point of the image from where the
reference white can be calculated using following
formulae:</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>refWhite_Y = 100.0<br>
refWhite_X = whitePoint_x / whitePoint_y * refWhite_Y<br>
refWhite_Z = (1.0 - whitePoint_x - whitePoint_y) /
whitePoint_y * refWhite_X</p></td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p>The conversion itself performed in two steps: at the
first one we will convert <i>CIE L*a*b* 1976</i> to <i>CIE
XYZ</i> using <b>TIFFCIELabToXYZ()</b> routine, and at the
second step we will convert <i>CIE XYZ</i> to <i>RGB</i>
using <b>TIFFXYZToRGB().</b> Look at the code sample
below:</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<pre>float *whitePoint;
float refWhite[3];
/* Initialize structures */
img-&gt;cielab = (TIFFCIELabToRGB *)
</pre>
</td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>_TIFFmalloc(sizeof(TIFFCIELabToRGB));</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>if (!cielab) {</p></td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="5" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>TIFFError(&quot;CIE L*a*b*-&gt;RGB&quot;,</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
</td>
<td width="6%">
<p>&quot;No space for CIE L*a*b*-&gt;RGB conversion
state.&quot;);</p>
</td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>exit(0);</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>}</p>
<!-- INDENTATION -->
<p>TIFFGetFieldDefaulted(tif, TIFFTAG_WHITEPOINT,
&amp;whitePoint);<br>
refWhite[1] = 100.0F;<br>
refWhite[0] = whitePoint[0] / whitePoint[1] *
refWhite[1];<br>
refWhite[2] = (1.0F - whitePoint[0] -
whitePoint[1])</p></td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>/ whitePoint[1] * refWhite[1];</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>if (TIFFCIELabToRGBInit(cielab, &amp;display_sRGB,
refWhite) &lt; 0) {</p></td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="5" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>TIFFError(&quot;CIE L*a*b*-&gt;RGB&quot;,</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
</td>
<td width="6%">
<p>&quot;Failed to initialize CIE L*a*b*-&gt;RGB conversion
state.&quot;);</p>
</td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>_TIFFfree(cielab);</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="0%"></td>
<td width="6%">
<p>exit(0);</p>
</td>
<td width="6%"></td>
<td width="62%">
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>}</p>
<!-- INDENTATION -->
<p>/* Now we can start to convert */<br>
uint32 r, g, b;<br>
uint32 L;<br>
int32 a, b;<br>
float X, Y, Z;</p>
<!-- INDENTATION -->
<p>for each pixel in image</p></td>
</table>
<!-- TABS -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>TIFFCIELabToXYZ(cielab, L, a, b, &amp;X, &amp;Y,
&amp;Z);</p>
</td>
<tr valign="top" align="left">
<td width="24%"></td>
<td width="75%">
<p>TIFFXYZToRGB(cielab, X, Y, Z, &amp;r, &amp;g,
&amp;b);</p>
</td>
</table>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="82%">
<p>/* Don&rsquo;t forget to free the state structure */<br>
_TIFFfree(cielab);</p></td>
</table>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>
<!-- INDENTATION -->
<table width="100%" border=0 rules="none" frame="void"
cols="2" cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="91%">
<p><b>TIFFRGBAImage</b>(3TIFF) <b>libtiff</b>(3TIFF),</p>
<!-- INDENTATION -->
<p>Libtiff library home page:
<b>http://www.remotesensing.org/libtiff/</b></p>
</td>
</table>
<hr>
</body>
</html>
Reference in New Issue View Git Blame Copy Permalink