registry/vulkan/appendices/compressedtex.txt

// Copyright (c) 2015-2018 Khronos Group. This work is licensed under a
// Creative Commons Attribution 4.0 International License; see
// http://creativecommons.org/licenses/by/4.0/

[appendix]
= Compressed Image Formats

The compressed texture formats used by Vulkan are described in the
specifically identified sections of the <<data-format,Khronos Data Format
Specification>>, version 1.1.

Unless otherwise described, the quantities encoded in these compressed
formats are treated as normalized, unsigned values.

Those formats listed as sRGB-encoded have in-memory representations of
[eq]#R#, [eq]#G# and [eq]#B# components which are nonlinearly-encoded as
[eq]#R'#, [eq]#G'#, and [eq]#B'#; any alpha component is unchanged.
As part of filtering, the nonlinear [eq]#R'#, [eq]#G'#, and [eq]#B'# values
are converted to linear [eq]#R#, [eq]#G#, and [eq]#B# components; any alpha
component is unchanged.
The conversion between linear and nonlinear encoding is performed as
described in the "`KHR_DF_TRANSFER_SRGB`" section of the Khronos Data Format
Specification.

<<<

[[appendix-compressedtex-bc]]
== Block-Compressed Image Formats

.Mapping of Vulkan BC formats to descriptions
[width="90%",options="header",cols="5,4"]
|====
| elink:VkFormat | <<data-format,Khronos Data Format Specification>> description
2+^| Formats described in the "`S3TC Compressed Texture Image Formats`" chapter
| ename:VK_FORMAT_BC1_RGB_UNORM_BLOCK |BC1 with no alpha
| ename:VK_FORMAT_BC1_RGB_SRGB_BLOCK  |BC1 with no alpha, sRGB-encoded
| ename:VK_FORMAT_BC1_RGBA_UNORM_BLOCK|BC1 with alpha
| ename:VK_FORMAT_BC1_RGBA_SRGB_BLOCK |BC1 with alpha, sRGB-encoded
| ename:VK_FORMAT_BC2_UNORM_BLOCK     |BC2
| ename:VK_FORMAT_BC2_SRGB_BLOCK      |BC2, sRGB-encoded
| ename:VK_FORMAT_BC3_UNORM_BLOCK     |BC3
| ename:VK_FORMAT_BC3_SRGB_BLOCK      |BC3, sRGB-encoded
2+^| Formats described in the "`RGTC Compressed Texture Image Formats`" chapter
| ename:VK_FORMAT_BC4_UNORM_BLOCK     |BC4 unsigned
| ename:VK_FORMAT_BC4_SNORM_BLOCK     |BC4 signed
| ename:VK_FORMAT_BC5_UNORM_BLOCK     |BC5 unsigned
| ename:VK_FORMAT_BC5_SNORM_BLOCK     |BC5 signed
2+^| Formats described in the "`BPTC Compressed Texture Image Formats`" chapter
| ename:VK_FORMAT_BC6H_UFLOAT_BLOCK   |BC6H (unsigned version)
| ename:VK_FORMAT_BC6H_SFLOAT_BLOCK   |BC6H (signed version)
| ename:VK_FORMAT_BC7_UNORM_BLOCK     |BC7
| ename:VK_FORMAT_BC7_SRGB_BLOCK      |BC7, sRGB-encoded
|====

<<<

[[appendix-compressedtex-etc2]]
== ETC Compressed Image Formats

The following formats are described in the "`ETC2 Compressed Texture Image
Formats`" chapter of the <<data-format,Khronos Data Format Specification>>.

.Mapping of Vulkan ETC formats to descriptions
[options="header",cols="1,1"]
|====
| elink:VkFormat | <<data-format,Khronos Data Format Specification>> description
| ename:VK_FORMAT_ETC2_R8G8B8_UNORM_BLOCK     |RGB ETC2
| ename:VK_FORMAT_ETC2_R8G8B8_SRGB_BLOCK      |RGB ETC2 with sRGB encoding
| ename:VK_FORMAT_ETC2_R8G8B8A1_UNORM_BLOCK   |RGB ETC2 with punch-through alpha
| ename:VK_FORMAT_ETC2_R8G8B8A1_SRGB_BLOCK    |RGB ETC2 with punch-through alpha and sRGB
| ename:VK_FORMAT_ETC2_R8G8B8A8_UNORM_BLOCK   |RGBA ETC2
| ename:VK_FORMAT_ETC2_R8G8B8A8_SRGB_BLOCK    |RGBA ETC2 with sRGB encoding
| ename:VK_FORMAT_EAC_R11_UNORM_BLOCK         |Unsigned R11 EAC
| ename:VK_FORMAT_EAC_R11_SNORM_BLOCK         |Signed R11 EAC
| ename:VK_FORMAT_EAC_R11G11_UNORM_BLOCK      |Unsigned RG11 EAC
| ename:VK_FORMAT_EAC_R11G11_SNORM_BLOCK      |Signed RG11 EAC
|====

<<<

[[appendix-compressedtex-astc]]
== ASTC Compressed Image Formats

ASTC formats are described in the "`ASTC Compressed Texture Image Formats`"
chapter of the <<data-format,Khronos Data Format Specification>>.

.Mapping of Vulkan ASTC formats to descriptions
[width="75%",options="header",cols="63%,15%,22%"]
|====
| elink:VkFormat ^| Compressed texel block dimensions ^| sRGB-encoded
| ename:VK_FORMAT_ASTC_4x4_UNORM_BLOCK    ^|[eq]#4 {times} 4# ^|No
| ename:VK_FORMAT_ASTC_4x4_SRGB_BLOCK     ^|[eq]#4 {times} 4# ^|Yes
| ename:VK_FORMAT_ASTC_5x4_UNORM_BLOCK    ^|[eq]#5 {times} 4# ^|No
| ename:VK_FORMAT_ASTC_5x4_SRGB_BLOCK     ^|[eq]#5 {times} 4# ^|Yes
| ename:VK_FORMAT_ASTC_5x5_UNORM_BLOCK    ^|[eq]#5 {times} 5# ^|No
| ename:VK_FORMAT_ASTC_5x5_SRGB_BLOCK     ^|[eq]#5 {times} 5# ^|Yes
| ename:VK_FORMAT_ASTC_6x5_UNORM_BLOCK    ^|[eq]#6 {times} 5# ^|No
| ename:VK_FORMAT_ASTC_6x5_SRGB_BLOCK     ^|[eq]#6 {times} 5# ^|Yes
| ename:VK_FORMAT_ASTC_6x6_UNORM_BLOCK    ^|[eq]#6 {times} 6# ^|No
| ename:VK_FORMAT_ASTC_6x6_SRGB_BLOCK     ^|[eq]#6 {times} 6# ^|Yes
| ename:VK_FORMAT_ASTC_8x5_UNORM_BLOCK    ^|[eq]#8 {times} 5# ^|No
| ename:VK_FORMAT_ASTC_8x5_SRGB_BLOCK     ^|[eq]#8 {times} 5# ^|Yes
| ename:VK_FORMAT_ASTC_8x6_UNORM_BLOCK    ^|[eq]#8 {times} 6# ^|No
| ename:VK_FORMAT_ASTC_8x6_SRGB_BLOCK     ^|[eq]#8 {times} 6# ^|Yes
| ename:VK_FORMAT_ASTC_8x8_UNORM_BLOCK    ^|[eq]#8 {times} 8# ^|No
| ename:VK_FORMAT_ASTC_8x8_SRGB_BLOCK     ^|[eq]#8 {times} 8# ^|Yes
| ename:VK_FORMAT_ASTC_10x5_UNORM_BLOCK   ^|[eq]#10 {times} 5# ^|No
| ename:VK_FORMAT_ASTC_10x5_SRGB_BLOCK    ^|[eq]#10 {times} 5# ^|Yes
| ename:VK_FORMAT_ASTC_10x6_UNORM_BLOCK   ^|[eq]#10 {times} 6# ^|No
| ename:VK_FORMAT_ASTC_10x6_SRGB_BLOCK    ^|[eq]#10 {times} 6# ^|Yes
| ename:VK_FORMAT_ASTC_10x8_UNORM_BLOCK   ^|[eq]#10 {times} 8# ^|No
| ename:VK_FORMAT_ASTC_10x8_SRGB_BLOCK    ^|[eq]#10 {times} 8# ^|Yes
| ename:VK_FORMAT_ASTC_10x10_UNORM_BLOCK  ^|[eq]#10 {times} 10# ^|No
| ename:VK_FORMAT_ASTC_10x10_SRGB_BLOCK   ^|[eq]#10 {times} 10# ^|Yes
| ename:VK_FORMAT_ASTC_12x10_UNORM_BLOCK  ^|[eq]#12 {times} 10# ^|No
| ename:VK_FORMAT_ASTC_12x10_SRGB_BLOCK   ^|[eq]#12 {times} 10# ^|Yes
| ename:VK_FORMAT_ASTC_12x12_UNORM_BLOCK  ^|[eq]#12 {times} 12# ^|No
| ename:VK_FORMAT_ASTC_12x12_SRGB_BLOCK   ^|[eq]#12 {times} 12# ^|Yes
|====