# VkImageCompressionFixedRateFlagBitsEXT(3) Manual Page

## Name

VkImageCompressionFixedRateFlagBitsEXT - Bitmask specifying fixed rate image compression rates

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## C Specification

Bits which can be set in VkImageCompressionControlEXT::`pFixedRateFlags`, specifying allowed compression rates for an image plane, are:

    // Provided by VK_EXT_image_compression_control
    typedef enum VkImageCompressionFixedRateFlagBitsEXT {
        VK_IMAGE_COMPRESSION_FIXED_RATE_NONE_EXT = 0,
        VK_IMAGE_COMPRESSION_FIXED_RATE_1BPC_BIT_EXT = 0x00000001,
        VK_IMAGE_COMPRESSION_FIXED_RATE_2BPC_BIT_EXT = 0x00000002,
        VK_IMAGE_COMPRESSION_FIXED_RATE_3BPC_BIT_EXT = 0x00000004,
        VK_IMAGE_COMPRESSION_FIXED_RATE_4BPC_BIT_EXT = 0x00000008,
        VK_IMAGE_COMPRESSION_FIXED_RATE_5BPC_BIT_EXT = 0x00000010,
        VK_IMAGE_COMPRESSION_FIXED_RATE_6BPC_BIT_EXT = 0x00000020,
        VK_IMAGE_COMPRESSION_FIXED_RATE_7BPC_BIT_EXT = 0x00000040,
        VK_IMAGE_COMPRESSION_FIXED_RATE_8BPC_BIT_EXT = 0x00000080,
        VK_IMAGE_COMPRESSION_FIXED_RATE_9BPC_BIT_EXT = 0x00000100,
        VK_IMAGE_COMPRESSION_FIXED_RATE_10BPC_BIT_EXT = 0x00000200,
        VK_IMAGE_COMPRESSION_FIXED_RATE_11BPC_BIT_EXT = 0x00000400,
        VK_IMAGE_COMPRESSION_FIXED_RATE_12BPC_BIT_EXT = 0x00000800,
        VK_IMAGE_COMPRESSION_FIXED_RATE_13BPC_BIT_EXT = 0x00001000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_14BPC_BIT_EXT = 0x00002000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_15BPC_BIT_EXT = 0x00004000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_16BPC_BIT_EXT = 0x00008000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_17BPC_BIT_EXT = 0x00010000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_18BPC_BIT_EXT = 0x00020000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_19BPC_BIT_EXT = 0x00040000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_20BPC_BIT_EXT = 0x00080000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_21BPC_BIT_EXT = 0x00100000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_22BPC_BIT_EXT = 0x00200000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_23BPC_BIT_EXT = 0x00400000,
        VK_IMAGE_COMPRESSION_FIXED_RATE_24BPC_BIT_EXT = 0x00800000,
    } VkImageCompressionFixedRateFlagBitsEXT;

## Description

- VK_IMAGE_COMPRESSION_FIXED_RATE_NONE_EXT specifies that fixed-rate compression must not be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_1BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [1,2) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_2BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [2,3) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_3BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [3,4) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_4BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [4,5) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_5BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [5,6) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_6BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [6,7) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_7BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [7,8) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_8BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [8,9) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_9BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [9,10) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_10BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [10,11) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_11BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of [11,12) bits per component may be used.

- VK_IMAGE_COMPRESSION_FIXED_RATE_12BPC_BIT_EXT specifies that fixed-rate compression with a bitrate of at least 12 bits per component may be used.

If the format has a different bit rate for different components, VkImageCompressionControlEXT::`pFixedRateFlags` describes the rate of the component with the largest number of bits assigned to it, scaled pro rata. For example, to request that a VK_FORMAT_A2R10G10B10_UNORM_PACK32 format be stored at a rate of 8 bits per pixel, use VK_IMAGE_COMPRESSION_FIXED_RATE_2BPC_BIT_EXT (10 bits for the largest component, stored at quarter the original size, 2.5 bits, rounded down).

If `flags` includes VK_IMAGE_COMPRESSION_FIXED_RATE_EXPLICIT_EXT, and multiple bits are set in VkImageCompressionControlEXT::`pFixedRateFlags` for a plane, implementations should apply the lowest allowed bitrate that is supported.

Note | The choice of “bits per component” terminology was chosen so that the same compression rate describes the same degree of compression applied to formats that differ only in the number of components. For example, VK_FORMAT_R8G8_UNORM compressed to half its original size is a rate of 4 bits per component, 8 bits per pixel. VK_FORMAT_R8G8B8A8_UNORM compressed to half its original size is 4 bits per component, 16 bits per pixel. Both of these cases can be requested with VK_IMAGE_COMPRESSION_FIXED_RATE_4BPC_BIT_EXT.

## See Also

VK_EXT_image_compression_control, VkImageCompressionFixedRateFlagsEXT

## Document Notes

For more information, see the Vulkan Specification.

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

## Copyright

Copyright 2014-2026 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0