The image descriptor structure describes the type and dimensions of the image or image array and is defined as:
image_type
Describes the image type and must be either CL_MEM_OBJECT_IMAGE1D, CL_MEM_OBJECT_IMAGE1D_BUFFER, CL_MEM_OBJECT_IMAGE1D_ARRAY, CL_MEM_OBJECT_IMAGE2D, CL_MEM_OBJECT_IMAGE2D_ARRAY, or CL_MEM_OBJECT_IMAGE3D.
image_width
The width of the image in pixels. For a 2D image and image array, the image width must be ≤ CL_DEVICE_IMAGE2D_MAX_WIDTH. For a 3D image, the image width must be ≤ CL_DEVICE_IMAGE3D_MAX_WIDTH. For a 1D image buffer, the image width must be ≤ CL_DEVICE_IMAGE_MAX_BUFFER_SIZE. For a 1D image and 1D image array, the image width must be ≤ CL_DEVICE_IMAGE2D_MAX_WIDTH.
image_height
The height of the image in pixels. This is only used if the image is a 2D, 3D or 2D image array. For a 2D image or image array, the image height must be ≤ CL_DEVICE_IMAGE2D_MAX_HEIGHT. For a 3D image, the image height must be ≤ CL_DEVICE_IMAGE3D_MAX_HEIGHT.
image_depth
The depth of the image in pixels. This is only used if the image is a 3D image and must be a value ≥ 1 and ≤ CL_DEVICE_IMAGE3D_MAX_DEPTH.
image_array_size
The number of images in the image array. This is only used if the image is a 1D or 2D image array. The values for image_array_size, if specified, must be a value ≥ 1 and ≤ CL_DEVICE_IMAGE_MAX_ARRAY_SIZE.
Note that reading and writing 2D image arrays from a kernel with image_array_size = 1 may be lower performance than 2D images.
image_row_pitch
The scan-line pitch in bytes. This must be 0 if host_ptr is NULL and can be either 0 or ≥ image_width * size of element in bytes if host_ptr is not NULL. If host_ptr is not NULL and image_row_pitch = 0, image_row_pitch is calculated as image_width * size of element in bytes. If image_row_pitch is not 0, it must be a multiple of the image element size in bytes.
image_slice_pitch
The size in bytes of each 2D slice in the 3D image or the size in bytes of each image in a 1D or 2D image array. This must be 0 if host_ptr is NULL. If host_ptr is not NULL, image_slice_pitch can be either 0 or ≥ image_row_pitch * image_height for a 2D image array or 3D image and can be either 0 or ≥ image_row_pitch for a 1D image array. If host_ptr is not NULL and image_slice_pitch = 0, image_slice_pitch is calculated as image_row_pitch * image_height for a 2D image array or 3D image and image_row_pitch for a 1D image array. If image_slice_pitch is not 0, it must be a multiple of the image_row_pitch.
num_mip_level, num_samples
, Must be 0.
buffer
Refers to a valid buffer memory object if image_type is CL_MEM_OBJECT_IMAGE1D_BUFFER. Otherwise it must be NULL. For a 1D image buffer object, the image pixels are taken from the buffer object's data store. When the contents of a buffer object's data store are modified, those changes are reflected in the contents of the 1D image buffer object and vice-versa at corresponding sychronization points. The image_width * size of element in bytes must be ≤ size of buffer object data store.
Concurrent reading from, writing to and copying between both a buffer object and 1D image buffer object associated with the buffer object is undefined. Only reading from both a buffer object and 1D image buffer object associated with the buffer object is defined.
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cl_image_format(3clc)
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OpenCL Specification
page 95, section 5.3.1.2 - Image Descriptor