## C Specification

A 1D image, 1D image buffer, 1D image array, 2D image, 2D image array and 3D image object can be created using the following function

cl_mem clCreateImage(
cl_context context,
cl_mem_flags flags,
const cl_image_format* image_format,
const cl_image_desc* image_desc,
void* host_ptr,
cl_int* errcode_ret);

## Parameters

• context is a valid OpenCL context on which the image object is to be created.

• flags is a bit-field that is used to specify allocation and usage information about the image memory object being created and is described in the supported memory flag values table.

• image_format is a pointer to a structure that describes format properties of the image to be allocated. A 1D image buffer or 2D image can be created from a buffer by specifying a buffer object in the image_descmem_object. A 2D image can be created from another 2D image object by specifying an image object in the image_descmem_object. Refer to the Image Format Descriptor section for a detailed description of the image format descriptor.

• image_desc is a pointer to a structure that describes type and dimensions of the image to be allocated. Refer to the Image Descriptor section for a detailed description of the image descriptor.

• host_ptr is a pointer to the image data that may already be allocated by the application. It is only used to initialize the image, and can be freed after the call to clCreateImage. Refer to the table below for a description of how large the buffer that host_ptr points to must be.

## Description

For all image types except CL_​MEM_​OBJECT_​IMAGE1D_​BUFFER, if the value specified for flags is 0, the default is used which is CL_​MEM_​READ_​WRITE.

For CL_​MEM_​OBJECT_​IMAGE1D_​BUFFER image type, or an image created from another memory object (image or buffer), if the CL_​MEM_​READ_​WRITE, CL_​MEM_​READ_​ONLY or CL_​MEM_​WRITE_​ONLY values are not specified in flags, they are inherited from the corresponding memory access qualifiers associated with mem_object. The CL_​MEM_​USE_​HOST_​PTR, CL_​MEM_​ALLOC_​HOST_​PTR and CL_​MEM_​COPY_​HOST_​PTR values cannot be specified in flags but are inherited from the corresponding memory access qualifiers associated with mem_object. If CL_​MEM_​COPY_​HOST_​PTR is specified in the memory access qualifier values associated with mem_object it does not imply any additional copies when the image is created from mem_object. If the CL_​MEM_​HOST_​WRITE_​ONLY, CL_​MEM_​HOST_​READ_​ONLY or CL_​MEM_​HOST_​NO_​ACCESS values are not specified in flags, they are inherited from the corresponding memory access qualifiers associated with mem_object.

Table 1. Required host_ptr buffer sizes for images
Image Type Size of buffer that host_ptr points to

CL_​MEM_​OBJECT_​IMAGE1D

Missing before version 1.2.

≥ image_row_pitch

CL_​MEM_​OBJECT_​IMAGE1D_​BUFFER

Missing before version 1.2.

≥ image_row_pitch

CL_​MEM_​OBJECT_​IMAGE2D

≥ image_row_pitch × image_height

CL_​MEM_​OBJECT_​IMAGE3D

≥ image_slice_pitch × image_depth

CL_​MEM_​OBJECT_​IMAGE1D_​ARRAY

Missing before version 1.2.

≥ image_slice_pitch × image_array_size

CL_​MEM_​OBJECT_​IMAGE2D_​ARRAY

Missing before version 1.2.

≥ image_slice_pitch × image_array_size

For a 3D image or 2D image array, the image data specified by host_ptr is stored as a linear sequence of adjacent 2D image slices or 2D images respectively. Each 2D image is a linear sequence of adjacent scanlines. Each scanline is a linear sequence of image elements.

For a 2D image, the image data specified by host_ptr is stored as a linear sequence of adjacent scanlines. Each scanline is a linear sequence of image elements.

For a 1D image array, the image data specified by host_ptr is stored as a linear sequence of adjacent 1D images. Each 1D image is stored as a single scanline which is a linear sequence of adjacent elements.

For 1D image or 1D image buffer, the image data specified by host_ptr is stored as a single scanline which is a linear sequence of adjacent elements.

Image elements are stored according to their image format as described in the Image Format Descriptor section.

• errcode_ret will return an appropriate error code. If errcode_ret is NULL, no error code is returned.

clCreateImage returns a valid non-zero image object created and the errcode_ret is set to CL_​SUCCESS if the image object is created successfully. Otherwise, it returns a NULL value with one of the following error values returned in errcode_ret:

• CL_​INVALID_​CONTEXT if context is not a valid context.

• CL_​INVALID_​VALUE if values specified in flags are not valid.

• CL_​INVALID_​IMAGE_​FORMAT_​DESCRIPTOR if values specified in image_format are not valid or if image_format is NULL.

• CL_​INVALID_​IMAGE_​FORMAT_​DESCRIPTOR if a 2D image is created from a buffer and the row pitch and base address alignment does not follow the rules described for creating a 2D image from a buffer.

• CL_​INVALID_​IMAGE_​FORMAT_​DESCRIPTOR if a 2D image is created from a 2D image object and the rules described above are not followed.

• CL_​INVALID_​IMAGE_​DESCRIPTOR if values specified in image_desc are not valid or if image_desc is NULL.

• CL_​INVALID_​IMAGE_​SIZE if image dimensions specified in image_desc exceed the maximum image dimensions described in the Device Queries table for all devices in context.

• CL_​INVALID_​HOST_​PTR if host_ptr is NULL and CL_​MEM_​USE_​HOST_​PTR or CL_​MEM_​COPY_​HOST_​PTR are set in flags or if host_ptr is not NULL but CL_​MEM_​COPY_​HOST_​PTR or CL_​MEM_​USE_​HOST_​PTR are not set in flags.

• CL_​INVALID_​VALUE if an image is being created from another memory object (buffer or image) under one of the following circumstances: 1) mem_object was created with CL_​MEM_​WRITE_​ONLY and flags specifies CL_​MEM_​READ_​WRITE or CL_​MEM_​READ_​ONLY, 2) mem_object was created with CL_​MEM_​READ_​ONLY and flags specifies CL_​MEM_​READ_​WRITE or CL_​MEM_​WRITE_​ONLY, 3) flags specifies CL_​MEM_​USE_​HOST_​PTR or CL_​MEM_​ALLOC_​HOST_​PTR or CL_​MEM_​COPY_​HOST_​PTR.

• CL_​INVALID_​VALUE if an image is being created from another memory object (buffer or image) and mem_object object was created with CL_​MEM_​HOST_​WRITE_​ONLY and flags specifies CL_​MEM_​HOST_​READ_​ONLY, or if mem_object was created with CL_​MEM_​HOST_​READ_​ONLY and flags specifies CL_​MEM_​HOST_​WRITE_​ONLY, or if mem_object was created with CL_​MEM_​HOST_​NO_​ACCESS and_flags_ specifies CL_​MEM_​HOST_​READ_​ONLY or CL_​MEM_​HOST_​WRITE_​ONLY.

• CL_​IMAGE_​FORMAT_​NOT_​SUPPORTED if the image_format is not supported.

• CL_​MEM_​OBJECT_​ALLOCATION_​FAILURE if there is a failure to allocate memory for image object.

• CL_​INVALID_​OPERATION if there are no devices in context that support images (i.e. CL_​DEVICE_​IMAGE_​SUPPORT specified in the Device Queries table is CL_​FALSE).

• CL_​OUT_​OF_​RESOURCES if there is a failure to allocate resources required by the OpenCL implementation on the device.

• CL_​OUT_​OF_​HOST_​MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.