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read_imagef (3D)
read_imagef (3D)
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read_imagef (3D) Do an element lookup in the 3D image object, returning floating-point values.

##

float4 `read_imagef` image3d_t image sampler_t sampler int4 coord float4 `read_imagef` image3d_t image sampler_t sampler float4 coord float4 `read_imagef` image3d_t image int4 coord

## Description

For the forms that take an image3d_t, use the coordinate (coord.x, coord.y, coord.z) to do an element lookup in the 3D image object specified by `image`. coord.w is ignored.

For the forms that take an image3d_array_t, use coord.xy to do an element lookup in the 2D image identified by coord.z in the 2D image array specified by `image`.

The samplerless read image functions behave exactly as the corresponding read image functions that take integer coordinates and a sampler with filter mode set to `CLK_FILTER_NEAREST`, normalized coordinates set to `CLK_NORMALIZED_COORDS_FALSE` and addressing mode to `CLK_ADDRESS_NONE`.

`read_imagef` returns floating-point values in the range [0.0... 1.0] for image objects created with `image_channel_data_type` set to one of the predefined packed formats or `CL_UNORM_INT8` or `CL_UNORM_INT16`.

`read_imagef` returns floating-point values in the range [-1.0... 1.0] for image objects created with `image_channel_data_type` set to `CL_SNORM_INT8`, or `CL_SNORM_INT16`.

`read_imagef` returns floating-point values for image objects created with `image_channel_data_type` set to `CL_HALF_FLOAT` or `CL_FLOAT`.

The `read_imagef` calls that take integer coordinates must use a sampler with filter mode set to `CLK_FILTER_NEAREST`, normalized coordinates set to `CLK_NORMALIZED_COORDS_FALSE` and addressing mode set to `CLK_ADDRESS_CLAMP_TO_EDGE`, `CLK_ADDRESS_CLAMP` or `CLK_ADDRESS_NONE`; otherwise the values returned are undefined.

Values returned by `read_imagef` for image objects with `image_channel_data_type` values not specified in the description above are undefined.

## Notes

General information about the `read_image`* functions follows.

&imageFunctionsInc; &imageMappingInc;

## Specification

OpenCL Specification

## Also see

Image Functions

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