// Copyright (c) 2015-2016 The Khronos Group Inc.
// Copyright notice at https://www.khronos.org/registry/speccopyright.html

[appendix]
= Compressed Image Formats

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

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

<<<

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

Those formats listed as ``sRGB-encoded'' have in-memory representations of
_R_, _G_ and _B_ components which are nonlinearly-encoded as
latexmath:[$R'$], latexmath:[$G'$], and latexmath:[$B'$]; any alpha
component is unchanged. As part of filtering, the nonlinear
latexmath:[$R'$], latexmath:[$G'$], and latexmath:[$B'$] values are
converted to linear _R_, _G_, and _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.

.Mapping of {apiname} BC formats to descriptions
[width="90%",options="header",cols="5,4"]
|==============================
| VkFormat | 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 Khronos Data Format Specification.

.Mapping of {apiname} ETC formats to descriptions
[options="header",cols="1,1"]
|==============================
| VkFormat | 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 punchthrough alpha
| ename:VK_FORMAT_ETC2_R8G8B8A1_SRGB_BLOCK    |RGB ETC2 with punchthrough 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 Khronos Data Format Specification.

.Mapping of {apiname} ASTC formats to descriptions
[width="80%",options="header",cols="6,1,1"]
|==============================
| VkFormat ^| Block size ^| sRGB output
| ename:VK_FORMAT_ASTC_4x4_UNORM_BLOCK    ^|latexmath:[$4\times 4$] ^|No
| ename:VK_FORMAT_ASTC_4x4_SRGB_BLOCK     ^|latexmath:[$4\times 4$] ^|Yes
| ename:VK_FORMAT_ASTC_5x4_UNORM_BLOCK    ^|latexmath:[$5\times 4$] ^|No
| ename:VK_FORMAT_ASTC_5x4_SRGB_BLOCK     ^|latexmath:[$5\times 4$] ^|Yes
| ename:VK_FORMAT_ASTC_5x5_UNORM_BLOCK    ^|latexmath:[$5\times 5$] ^|No
| ename:VK_FORMAT_ASTC_5x5_SRGB_BLOCK     ^|latexmath:[$5\times 5$] ^|Yes
| ename:VK_FORMAT_ASTC_6x5_UNORM_BLOCK    ^|latexmath:[$6\times 5$] ^|No
| ename:VK_FORMAT_ASTC_6x5_SRGB_BLOCK     ^|latexmath:[$6\times 5$] ^|Yes
| ename:VK_FORMAT_ASTC_6x6_UNORM_BLOCK    ^|latexmath:[$6\times 6$] ^|No
| ename:VK_FORMAT_ASTC_6x6_SRGB_BLOCK     ^|latexmath:[$6\times 6$] ^|Yes
| ename:VK_FORMAT_ASTC_8x5_UNORM_BLOCK    ^|latexmath:[$8\times 5$] ^|No
| ename:VK_FORMAT_ASTC_8x5_SRGB_BLOCK     ^|latexmath:[$8\times 5$] ^|Yes
| ename:VK_FORMAT_ASTC_8x6_UNORM_BLOCK    ^|latexmath:[$8\times 6$] ^|No
| ename:VK_FORMAT_ASTC_8x6_SRGB_BLOCK     ^|latexmath:[$8\times 6$] ^|Yes
| ename:VK_FORMAT_ASTC_8x8_UNORM_BLOCK    ^|latexmath:[$8\times 8$] ^|No
| ename:VK_FORMAT_ASTC_8x8_SRGB_BLOCK     ^|latexmath:[$8\times 8$] ^|Yes
| ename:VK_FORMAT_ASTC_10x5_UNORM_BLOCK   ^|latexmath:[$10\times 5$] ^|No
| ename:VK_FORMAT_ASTC_10x5_SRGB_BLOCK    ^|latexmath:[$10\times 5$] ^|Yes
| ename:VK_FORMAT_ASTC_10x6_UNORM_BLOCK   ^|latexmath:[$10\times 6$] ^|No
| ename:VK_FORMAT_ASTC_10x6_SRGB_BLOCK    ^|latexmath:[$10\times 6$] ^|Yes
| ename:VK_FORMAT_ASTC_10x8_UNORM_BLOCK   ^|latexmath:[$10\times 8$] ^|No
| ename:VK_FORMAT_ASTC_10x8_SRGB_BLOCK    ^|latexmath:[$10\times 8$] ^|Yes
| ename:VK_FORMAT_ASTC_10x10_UNORM_BLOCK  ^|latexmath:[$10\times 10$] ^|No
| ename:VK_FORMAT_ASTC_10x10_SRGB_BLOCK   ^|latexmath:[$10\times 10$] ^|Yes
| ename:VK_FORMAT_ASTC_12x10_UNORM_BLOCK  ^|latexmath:[$12\times 10$] ^|No
| ename:VK_FORMAT_ASTC_12x10_SRGB_BLOCK   ^|latexmath:[$12\times 10$] ^|Yes
| ename:VK_FORMAT_ASTC_12x12_UNORM_BLOCK  ^|latexmath:[$12\times 12$] ^|No
| ename:VK_FORMAT_ASTC_12x12_SRGB_BLOCK   ^|latexmath:[$12\times 12$] ^|Yes
|==============================