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| <refentry> |
| <refentryinfo> |
| <keywordset> |
| <keyword> |
| read_imagef (1D or 2D) |
| </keyword> |
| </keywordset> |
| </refentryinfo> |
| |
| <refmeta> |
| <refentrytitle>read_imagef (1D or 2D)</refentrytitle> |
| |
| <refmiscinfo> |
| <copyright> |
| <year>2007-2009</year> |
| <holder>The Khronos Group Inc. |
| Permission is hereby granted, free of charge, to any person obtaining a |
| copy of this software and/or associated documentation files (the |
| "Materials"), to deal in the Materials without restriction, including |
| without limitation the rights to use, copy, modify, merge, publish, |
| distribute, sublicense, and/or sell copies of the Materials, and to |
| permit persons to whom the Materials are furnished to do so, subject to |
| the condition that this copyright notice and permission notice shall be included |
| in all copies or substantial portions of the Materials.</holder> |
| </copyright> |
| </refmiscinfo> |
| <manvolnum>2</manvolnum> |
| </refmeta> |
| |
| <!-- ================================ SYNOPSIS --> |
| |
| <refnamediv id="read_image2d"> |
| <refname>read_imagef (1D or 2D)</refname> |
| |
| <refpurpose> |
| Do an element lookup in the 1D or 2D image object, returning floating-point values. |
| </refpurpose> |
| </refnamediv> |
| |
| <refsynopsisdiv xmlns:xlink="http://www.w3.org/1999/xlink"><title></title> |
| <funcsynopsis> |
| <funcprototype> |
| <funcdef> |
| float4 |
| <function> |
| read_imagef |
| </function> |
| </funcdef> |
| <paramdef>image2d_t<parameter>image</parameter></paramdef> |
| <paramdef><link xlink:href="otherDataTypes.html">sampler_t</link><parameter>sampler</parameter></paramdef> |
| <paramdef>int2<parameter>coord</parameter></paramdef> |
| </funcprototype> |
| </funcsynopsis> |
| |
| <funcsynopsis> |
| <funcprototype> |
| <funcdef> |
| float4 |
| <function> |
| read_imagef |
| </function> |
| </funcdef> |
| <paramdef>image2d_t<parameter>image</parameter></paramdef> |
| <paramdef><link xlink:href="otherDataTypes.html">sampler_t</link><parameter>sampler</parameter></paramdef> |
| <paramdef>float2<parameter>coord</parameter></paramdef> |
| </funcprototype> |
| </funcsynopsis> |
| </refsynopsisdiv> |
| |
| <!-- ================================ DESCRIPTION --> |
| |
| <refsect1 id="description"><title>Description</title> |
| <para> |
| Use the coordinate <emphasis>(x, y)</emphasis> to do an element lookup in the 1D or 2D image object specified by <varname>image</varname>. |
| </para> |
| <para> |
| <function>read_imagef</function> returns floating-point values in the range [0.0... 1.0] for image objects created with <varname>image_channel_data_type</varname> set to one of the predefined packed formats or CL_UNORM_INT8 or CL_UNORM_INT16. |
| </para> |
| <para> |
| <function>read_imagef</function> returns floating-point values in the range [-1.0... 1.0] for image objects created with <varname>image_channel_data_type</varname> set to CL_SNORM_INT8, or CL_SNORM_INT16. |
| </para> |
| <para> |
| <function>read_imagef</function> returns floating-point values for image objects created with <varname>image_channel_data_type</varname> set to CL_HALF_FLOAT or CL_FLOAT. |
| </para> |
| <para> |
| The <function>read_imagef</function> calls that take integer coordinates must use a sampler with filter mode set to CLK_FILTER_NEAREST, normalized coordinates set to CLK_NORMALIZED_COORDS_FALSE and addressing mode set to CLK_ADDRESS_CLAMP_TO_EDGE, CLK_ADDRESS_CLAMP or CLK_ADDRESS_NONE; otherwise the values returned are undefined. |
| </para> |
| <para> |
| Values returned by <function>read_imagef</function> for image objects with <varname>image_channel_data_type</varname> values not specified in the description above are undefined. |
| </para> |
| </refsect1> |
| |
| <!-- ================================ NOTES --> |
| |
| <refsect1 id="notes"><title>Notes</title> |
| <para> |
| The following table describes the mapping of the number of channels of an image element to the appropriate components in the float4, int4 or unsigned int4 vector data type for the color values returned by <function>read_image{f|i|ui}</function> or supplied to <function>write_image{f|i|ui}</function>. The unmapped components will be set to <constant>0.0</constant> for red, green and blue channels and will be set to <constant>1.0</constant> for the alpha channel. |
| </para> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2" align="center" colsep="1" rowsep="1"> |
| <colspec colname="col1" colnum="1" /> |
| <colspec colname="col2" colnum="2" /> |
| <thead> |
| <row> |
| <entry>Channel Order</entry> |
| <entry>float4, int4 or unsigned int4 components of channel data</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry><constant>CL_R</constant></entry> |
| <entry><constant>(r, 0.0, 0.0, 1.0)</constant></entry> |
| </row> |
| <row> |
| <entry><constant>CL_A</constant></entry> |
| <entry><constant>(0.0, 0.0, 0.0, a)</constant></entry> |
| </row> |
| <row> |
| <entry><constant>CL_RG</constant></entry> |
| <entry><constant>(r, g, 0.0, 1.0)</constant></entry> |
| </row> |
| <row> |
| <entry><constant>CL_RA</constant></entry> |
| <entry><constant>(r, 0.0, 0.0, a)</constant></entry> |
| </row> |
| <row> |
| <entry><constant>CL_RGB</constant></entry> |
| <entry><constant>(r, g, b, 1.0)</constant></entry> |
| </row> |
| <row> |
| <entry><constant>CL_RGBA, CL_BGRA, CL_ARGB</constant></entry> |
| <entry><constant>(r, g, b, a)</constant></entry> |
| </row> |
| <row> |
| <entry><constant>CL_INTENSITY</constant></entry> |
| <entry><constant>(I, I, I, I)</constant></entry> |
| </row> |
| <row> |
| <entry><constant>CL_LUMINANCE</constant></entry> |
| <entry><constant>(L, L, L, 1.0)</constant></entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| </refsect1> |
| <!-- ================================ EXAMPLE --> |
| <!-- DO NOT DELETE IN CASE AN EXAMPLE IS ADDED IN THE FUTURE --> |
| <!-- |
| <refsect2 id="example1"> |
| <title> |
| Example |
| </title> |
| |
| <informaltable frame="none"> |
| <tgroup cols="1" align="left" colsep="0" rowsep="0"> |
| <colspec colname="col1" colnum="1" /> |
| <tbody> |
| <row> |
| <entry> |
| Example goes here - it will be set in "code" type with white space preserved. |
| </entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </refsect2> |
| --> |
| |
| |
| <!-- ================================ SPECIFICATION --> |
| <!-- Set the "uri" attribute in the <olink /> element to the "named destination" for the PDF page |
| --> |
| <refsect1 id="specification"><title>Specification</title> |
| <para> |
| <imageobject> |
| <imagedata fileref="pdficon_small1.gif" format="gif" /> |
| </imageobject> |
| |
| <olink uri="imageFunctions">OpenCL Specification</olink> |
| </para> |
| </refsect1> |
| |
| |
| <!-- ================================ ALSO SEE --> |
| |
| <refsect1 id="seealso"><title>Also see</title> |
| <para> |
| <citerefentry href="imageFunctions"><refentrytitle>Image Functions</refentrytitle></citerefentry> |
| </para> |
| </refsect1> |
| |
| |
| |
| <!-- ============================== COPYRIGHT --> |
| <!-- Content included from copyright.inc.xsl --> |
| |
| <refsect3 id="Copyright"><title></title> |
| <imageobject> |
| <imagedata fileref="KhronosLogo.jpg" format="jpg" /> |
| </imageobject> |
| <para /> |
| </refsect3> |
| |
| </refentry> |
| |
