Image Read and Write Functions

Built-in functions to read, write, and query image memory objects. Click an item in the table below for details about that function.

read_imagef for 1D Do an element lookup in the 1D image object with or without a sampler, returning floating-point values.
read_image{i|ui} for 1D Do an element lookup in the 1D image object with or without a sampler, returning unnormalized signed integer and unsigned integer values.
read_imageh for 1D OPTIONAL function to do an element lookup in the 1D image object with or without a sampler, returning floating-point values. Enabled with cl_khr_fp16.
write_image {f|i|ui|h} for 1D Write color value to location in the 2D image object. The half type is enabled with cl_khr_fp16.
read_imagef for 2D Do an element lookup in the 2D image object with or without a sampler, returning floating-point values.
read_image{i|ui} for 2D Do an element lookup in the 2D image object with or without a sampler, returning unnormalized signed integer and unsigned integer values.
read_imageh for 2D OPTIONAL function to do an element lookup in the 2D image object with or without a sampler, returning floating-point values. Enabled with cl_khr_fp16.
write_image {f|i|ui|h} for 2D Write color value to location in the 2D image object. The half type is enabled with cl_khr_fp16.
read_imagef for 3D Do an element lookup in the 3D image object with or without a sampler, returning floating-point values.
read_image{i|ui} for 3D Do an element lookup in the 3D image object with or without a sampler, returning unnormalized signed integer and unsigned integer values.
read_imageh for 3D OPTIONAL function to do an element lookup in the 3D image object with or without a sampler, returning floating-point values. Enabled with cl_khr_fp16.
write_image {f|i|ui|h} for 3D Write color value to location in the 2D image object. The half type is enabled with cl_khr_fp16.
get_image_width Return the image width in pixels
get_image_height Return the image height in pixels.
get_image_depth Return the 3D image depth in pixels
get_image_channel_data_type Return the image channel data type
get_image_channel_order Return the image channel order
get_image_dim Return the image dimensions
get_image_array_size Return the number of images in an image array

Notes

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.

Image memory objects that are being read by a kernel should be declared with the __read_only qualifier. write_image calls to image memory objects declared with the __read_only qualifier will generate a compilation error. Image memory objects that are being written to by a kernel should be declared with the __write_only qualifier. read_image calls to image memory objects declared with the __write_only qualifier will generate a compilation error. read_image and write_image calls to the same image memory object in a kernel are not supported.

The read_image calls returns a four component floating-point, integer or unsigned integer color value. The color values returned by read_image are identified as x, y, z, w where x refers to the red component, y refers to the green component, z refers to the blue component and w refers to the alpha component.

Specification

OpenCL Specification

Also see

sampler_t, cl_khr_3d_image_writes

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