OpenCL Programming by Example

Samplers

One of the parameters passed to read_image and write_image built-ins is the image sampler object. Sampler variables in a program are declared to be of type sampler_t and enable the read and write routines to sample an input pixel value. The samplers are created inside a kernel by using the OR operator for the normalized coordinates, the addressing modes, and the filtering modes. Example is as follows:

const sampler_t sampler = CLK_NORMALIZED_COORDS_FALSE | CLK_ADDRESS_NONE | CLK_FILTER_NEAREST;

Normalized coordinates can be set to either of the following two:

• CLK_NORMALIZED_COORDS_TRUE: The pixel coordinate values are in the range of 0 to 1.0.
• CLK_NORMALIZED_COORDS_FALSE: The pixel coordinate values will be having an extent of image dimensions. ...