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| <title>Image Read, Write, and Query Functions</title> |
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| <meta name="keywords" content="Image Read and Write Functions" /> |
| </head> |
| <body> |
| <div class="refentry"> |
| <a id="id-1"></a> |
| <div class="titlepage"></div> |
| <div xmlns="" class="refnamediv"> |
| <h1>Image Read and Write Functions</h1> |
| <p>Built-in functions to read, write, and query image memory objects. Click an item in the table below for details about that function.</p> |
| </div> |
| <div class="refsect1"> |
| <a id="springboard"></a> |
| <h2></h2> |
| <div class="informaltable"> |
| <table class="informaltable" border="1"> |
| <colgroup> |
| <col align="left" class="col1" /> |
| <col align="left" class="col2" /> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imagef1d.html"><span class="citerefentry"><span class="refentrytitle">read_imagef</span></span></a> for 1D</td> |
| <td align="left"> |
| Do an element lookup in the 1D image object with or without a sampler, |
| returning floating-point values (including optional mipmap support). |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imagei1d.html"><span class="citerefentry"><span class="refentrytitle">read_image{i|ui}</span></span></a> for 1D</td> |
| <td align="left"> |
| Do an element lookup in the 1D image object with or without a sampler, |
| returning unnormalized signed integer and unsigned integer values (including optional mipmap support). |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imageh1d.html"><span class="citerefentry"><span class="refentrytitle">read_imageh</span></span></a> for 1D</td> |
| <td align="left"> |
| OPTIONAL function to do an element lookup in the 1D image object |
| with or without a sampler, returning floating-point values. Enabled with |
| <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>. |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="write_image1d.html"><span class="citerefentry"><span class="refentrytitle">write_image {f|i|ui|h}</span></span></a> for 1D |
| </td> |
| <td align="left"> |
| Write <code class="varname">color</code> value to location in the 2D image object (including optional mipmap support). |
| The <span class="type">half</span> type is enabled with |
| <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>. |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imagef2d.html"><span class="citerefentry"><span class="refentrytitle">read_imagef</span></span></a> for 2D</td> |
| <td align="left"> |
| Do an element lookup in the 2D image object with or without a sampler, |
| returning floating-point values (including optional mipmap support). |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imagei2d.html"><span class="citerefentry"><span class="refentrytitle">read_image{i|ui}</span></span></a> for 2D |
| </td> |
| <td align="left"> |
| Do an element lookup in the 2D image object with or without a sampler, |
| returning unnormalized signed integer and unsigned integer values (including optional mipmap support). |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imageh2d.html"><span class="citerefentry"><span class="refentrytitle">read_imageh</span></span></a> for 2D</td> |
| <td align="left"> |
| OPTIONAL function to do an element lookup in the 2D image object with |
| or without a sampler, returning floating-point values. Enabled with |
| <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>. |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="write_image2d.html"><span class="citerefentry"><span class="refentrytitle">write_image {f|i|ui|h}</span></span></a> for 2D |
| </td> |
| <td align="left"> |
| Write <code class="varname">color</code> value to location in the 2D image object (including optional mipmap support). |
| The <span class="type">half</span> type is enabled with |
| <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>. |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imagef3d.html"><span class="citerefentry"><span class="refentrytitle">read_imagef</span></span></a> for 3D |
| </td> |
| <td align="left"> |
| Do an element lookup in the 3D image object with or without a sampler, |
| returning floating-point values (including optional mipmap support). |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imagei3d.html"><span class="citerefentry"><span class="refentrytitle">read_image{i|ui}</span></span></a> for 3D |
| </td> |
| <td align="left"> |
| Do an element lookup in the 3D image object with or without a sampler, |
| returning unnormalized signed integer and unsigned integer values (including optional mipmap support). |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="read_imageh3d.html"><span class="citerefentry"><span class="refentrytitle">read_imageh</span></span></a> for 3D |
| </td> |
| <td align="left"> |
| OPTIONAL function to do an element lookup in the 3D image object with or |
| without a sampler, returning floating-point values. Enabled with |
| <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>. |
| </td> |
| </tr> |
| <tr> |
| <td align="left"><a class="citerefentry" href="write_image3d.html"><span class="citerefentry"><span class="refentrytitle">write_image {f|i|ui|h}</span></span></a> for 3D |
| </td> |
| <td align="left"> |
| Write <code class="varname">color</code> value to location in the 2D image object (including optional mipmap support). |
| The <span class="type">half</span> type is enabled with |
| <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>. |
| </td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_width.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_width</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the image width in pixels</td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_height.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_height</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the image height in pixels.</td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_depth.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_depth</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the 3D image depth in pixels</td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_channel_data_type.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_channel_data_type</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the image channel data type</td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_channel_order.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_channel_order</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the image channel order</td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_dim.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_dim</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the image dimensions</td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_array_size.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_array_size</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the number of images in an image array</td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_num_mip_levels.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_num_mip_levels</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the number of mip-levels. Enabled with extension <a class="citerefentry" href="cl_khr_mipmap_image.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_mipmap_image</span></span></a></td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <a class="citerefentry" href="get_image_num_samples.html"> |
| <span class="citerefentry"> |
| <span class="refentrytitle">get_image_num_samples</span> |
| </span> |
| </a> |
| </td> |
| <td align="left">Return the number of samples in the 2D MSAA image. Enabled with extension <a class="citerefentry" href="cl_khr_gl_msaa_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_msaa_sharing</span></span></a></td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| </div> |
| <div class="refsect1"> |
| <a id="notes"></a> |
| <h2>Notes</h2> |
| <p> |
| The built-in functions defined in this section |
| can only be used with image memory objects. An image memory object can be accessed by |
| specific function calls that read from and/or write to specific locations in the image. |
| </p> |
| <p> |
| Note that image writes to sRGB images are only supported if the |
| <a class="citerefentry" href="cl_khr_srgb_image_writes.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_srgb_image_writes</span></span></a> |
| extension is supported; |
| otherwise the behavior of writing to a sRGB image is undefined. |
| </p> |
| <p> |
| Image memory objects that are being read by a kernel should be declared with the <a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">read_only</span></span></a> |
| qualifier. <code class="function">write_image</code> calls to image memory objects declared with the |
| <a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">read_only</span></span></a> |
| qualifier will generate a compilation error. Image memory objects that |
| are being written to by a kernel should be declared with the <a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">write_only</span></span></a> qualifier. |
| <code class="function">read_image</code> calls to image memory objects declared with the <a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">write_only</span></span></a> |
| qualifier will generate a compilation error. <code class="function">read_image</code> and |
| <code class="function">write_image</code> calls to the same image memory object in a kernel are |
| not supported. |
| Image memory objects that are being read and written by a kernel should be declared with the |
| <a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">read_write</span></span></a> |
| qualifier. |
| </p> |
| <p> |
| The <code class="function">read_image</code> calls returns a four component floating-point, integer or |
| unsigned integer color value. The color values returned by <code class="function">read_image</code> |
| are identified as <code class="code">x, y, z, w</code> where <code class="code">x</code> refers to the red component, |
| <code class="code">y</code> refers to the green component, <code class="code">z</code> refers to the blue component |
| and <code class="code">w</code> refers to the alpha component. |
| </p> |
| <p> |
| The samplerless read image functions behave exactly as the corresponding read |
| image functions that take integer coordinates and a sampler with filter mode |
| set to <code class="constant">CLK_FILTER_NEAREST</code>, normalized coordinates set |
| to <code class="constant">CLK_NORMALIZED_COORDS_FALSE</code> and addressing mode to |
| <code class="constant">CLK_ADDRESS_NONE</code>. |
| </p> |
| <h4><a id="id-1.5.7"></a>sRGB Images</h4> |
| <p> |
| |
| The built-in image read functions will perform |
| sRGB to linear RGB conversions if the image is |
| an sRGB image. Writing to sRGB images from a |
| kernel is an optional extension. The |
| <a class="citerefentry" href="cl_khr_srgb_image_writes.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_srgb_image_writes</span></span></a> |
| extension will be reported in the |
| <code class="constant">CL_DEVICE_EXTENSIONS</code> string |
| if a device supports writing to sRGB images using |
| <a class="citerefentry" href="imageFunctions.html"><span class="citerefentry"><span class="refentrytitle">write_imagef</span></span></a>. |
| <a class="citerefentry" href="clGetSupportedImageFormats.html"><span class="citerefentry"><span class="refentrytitle">clGetSupportedImageFormats</span></span></a> |
| will return the supported sRGB images if |
| <code class="constant">CL_MEM_READ_WRITE</code> or |
| <code class="constant">CL_MEM_WRITE_ONLY</code> is specified in |
| <code class="varname">flags</code> argument and the |
| device supports writing to an sRGB image. If |
| <a class="citerefentry" href="cl_khr_srgb_image_writes.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_srgb_image_writes</span></span></a> |
| is supported, the |
| built-in image write functions will perform |
| the linear to sRGB conversion. |
| </p> |
| <p> |
| Only the R, G and B components are converted from |
| linear to sRGB and vice-versa. The alpha |
| component is returned as is. |
| </p> |
| </div> |
| <div class="refsect1"> |
| <a id="specification"></a> |
| <h2>Specification</h2> |
| <p> |
| <img src="pdficon_small1.gif" /> |
| |
| <a href="https://www.khronos.org/registry/cl/specs/opencl-2.1-openclc.pdf#page=127" target="OpenCL Spec">OpenCL Specification</a> |
| </p> |
| </div> |
| <div class="refsect1"> |
| <a id="seealso"></a> |
| <h2>Also see</h2> |
| <p> |
| <a class="citerefentry" href="sampler_t.html"><span class="citerefentry"><span class="refentrytitle">sampler_t</span></span></a>, |
| <a class="citerefentry" href="cl_khr_srgb_image_writes.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_srgb_image_writes</span></span></a>, |
| <a class="citerefentry" href="cl_khr_mipmap_image.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_mipmap_image</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 © 2007-2015 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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