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    <title>read_image (1D or 2D, Half)</title>
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      <div class="titlepage"></div>
      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="read_image2d"></a>
        <h1>read_imageh (1D or 2D, Half)</h1>
        <p>
            Do an element lookup in the 1D or 2D image object, returning half floating-point values.
        </p>
      </div>
      <div class="refsynopsisdiv">
        <h2></h2>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
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              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef">
                    half4
                    <strong class="fsfunc">                   
                        read_imageh
                    </strong>
                (</code>
                <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="otherDataTypes.html" target="_top">image2d_t</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">image</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="otherDataTypes.html" target="_top">sampler_t</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">sampler</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>int2 <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">coord</var><code>)</code></td>
            </tr>
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        </div>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
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              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef">
                    half4
                    <strong class="fsfunc">                   
                        read_imageh
                    </strong>
                (</code>
                <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="otherDataTypes.html" target="_top">image2d_t</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">image</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="otherDataTypes.html" target="_top">sampler_t</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">sampler</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>float2 <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">coord</var><code>)</code></td>
            </tr>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
		Use the coordinate <span class="emphasis"><em>(x, y)</em></span> to do an element lookup in the 1D or 2D image object specified by <code class="varname">image</code>.
		</p>
        <p>		
<code class="function">read_imageh</code> returns half floating-point values in the range [0.0... 1.0] for image objects created with <code class="varname">image_channel_data_type</code> set to one of the predefined packed formats or CL_UNORM_INT8 or CL_UNORM_INT16.
		</p>
        <p>	
<code class="function">read_imageh</code> returns half floating-point values in the range [-1.0... 1.0] for image objects created with <code class="varname">image_channel_data_type</code> set to CL_SNORM_INT8, or CL_SNORM_INT16.
		</p>
        <p>	
<code class="function">read_imageh</code> returns half floating-point values for image objects created with <code class="varname">image_channel_data_type</code> set to CL_HALF_FLOAT.
		</p>
        <p>	
The <code class="function">read_imageh</code> 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.
		</p>
        <p>	
Values returned by <code class="function">read_imageh</code> for image objects with <code class="varname">image_channel_data_type</code> values not specified in the description above are undefined.
		</p>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
	 
		</p>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />
                                               
            <a href="http://www.khronos.org/registry/cl/specs/opencl-1.0.pdf#page=190" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="imageFunctions.html"><span class="citerefentry"><span class="refentrytitle">Image Functions</span></span></a> 
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2009 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. 
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