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cl_image_format.adoc

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cl_image_format

The image format descriptor structure is defined as:

                        typedef struct _cl_image_format {
          cl_channel_order image_channel_order;
          cl_channel_type  image_channel_data_type;
} cl_image_format;

Members

image_channel_order

Specifies the number of channels and the channel layout i.e. the memory layout in which channels are stored in the image. Valid values are described in the table (Table 5.6) below.

Format Description

CL_R, CL_Rx, or CL_A

CL_INTENSITY

This format can only be used if channel data type = CL_UNORM_INT8, CL_UNORM_INT16, CL_SNORM_INT8, CL_SNORM_INT16, CL_HALF_FLOAT, or CL_FLOAT.

CL_LUMINANCE

This format can only be used if channel data type = CL_UNORM_INT8, CL_UNORM_INT16, CL_SNORM_INT8, CL_SNORM_INT16, CL_HALF_FLOAT, or CL_FLOAT.

CL_DEPTH

This format can only be used if channel data type = CL_UNORM_INT16 or CL_FLOAT.

CL_RG, CL_RGx, or CL_RA

CL_RGB or CL_RGBx

These formats can only be used if channel data type = CL_UNORM_SHORT_565, CL_UNORM_SHORT_555 or CL_UNORM_INT101010.

CL_RGBA

CL_sRGB, CL_sRGBx, CL_sRGBA, CL_sBGRA

These formats can only be used if channel data type = CL_UNORM_INT8.

CL_ARGB, CL_BGRA, CL_ABGR

These formats can only be used if channel data type = CL_UNORM_INT8, CL_SNORM_INT8, CL_SIGNED_INT8 or CL_UNSIGNED_INT8.

CL_DEPTH_STENCIL

This format can only be used if channel data type = CL_UNORM_INT24 or CL_FLOAT (applies if the cl_khr_gl_depth_images extension is enabled).
image_channel_data_type

Describes the size of the channel data type. The number of bits per element determined by the image_channel_data_type and image_channel_order must be a power of two. The list of supported values is described in the table (Table 5.7) below.

Image Channel Data Type Description

CL_SNORM_INT8

Each channel component is a normalized signed 8-bit integer value.

CL_SNORM_INT16

Each channel component is a normalized signed 16-bit integer value.

CL_UNORM_INT8

Each channel component is a normalized unsigned 8-bit integer value.

CL_UNORM_INT16

Each channel component is a normalized unsigned 16-bit integer value.

CL_UNORM_SHORT_565

Represents a normalized 5-6-5 3-channel RGB image. The channel order must be CL_RGB or CL_RGBx.

CL_UNORM_SHORT_555

Represents a normalized x-5-5-5 4-channel xRGB image. The channel order must be CL_RGB or CL_RGBx.

CL_UNORM_INT_101010

Represents a normalized x-10-10-10 4-channel xRGB image. The channel order must be CL_RGB or CL_RGBx.

CL_SIGNED_INT8

Each channel component is an unnormalized signed 8-bit integer value.

CL_SIGNED_INT16

Each channel component is an unnormalized signed 16-bit integer value.

CL_SIGNED_INT32

Each channel component is an unnormalized signed 32-bit integer value.

CL_UNSIGNED_INT8

Each channel component is an unnormalized unsigned 8-bit integer value.

CL_UNSIGNED_INT16

Each channel component is an unnormalized unsigned 16-bit integer value.

CL_UNSIGNED_INT32

Each channel component is an unnormalized unsigned 32-bit integer value.

CL_HALF_FLOAT

Each channel component is a 16-bit half-float value.

CL_FLOAT

Each channel component is a single precision floating-point value.

CL_FLOAT

Each channel component is a single precision floating point value (applies if the cl_khr_gl_depth_images extension is enabled).

CL_UNORM_INT24

Each channel component is a normalized unsigned 24-bit integer value (applies if the cl_khr_gl_depth_images extension is enabled).

Description

For example, to specify a normalized unsigned 8-bit / channel RGBA image:

          image_channel_order = CL_RGBA
          image_channel_data_type = CL_UNORM_INT8

image_channel_data_type values of CL_UNORM_SHORT_565, CL_UNORM_SHORT_555, CL_UNORM_INT_101010, and CL_UNORM_INT_101010_2 are special cases of packed image formats where the channels of each element are packed into a single unsigned short or unsigned int. For these special packed image formats, the channels are normally packed with the first channel in the most significant bits of the bitfield, and successive channels occupying progressively less significant locations. For CL_UNORM_SHORT_565, R is in bits 15:11, G is in bits 10:5 and B is in bits 4:0. For CL_UNORM_SHORT_555, bit 15 is undefined, R is in bits 14:10, G in bits 9:5 and B in bits 4:0. For CL_UNORM_INT_101010, bits 31:30 are undefined, R is in bits 29:20, G in bits 19:10 and B in bits 9:0. For CL_UNORM_INT_101010_2, R is in bits 31:22, G in bits 21:12, B in bits 11:2 and A in bits 1:0.

OpenCL implementations must maintain the minimum precision specified by the number of bits in image_channel_data_type. If the image format specified by image_channel_order, and image_channel_data_type cannot be supported by the OpenCL implementation, then the call to clCreateImage will return a NULL memory object.