Khronos Data Format Specification Andrew Garrard Version 1.2, Revision 1 2019-03-31 1 / 207 Khronos Data Format Specification License Information Copyright (C) 2014-2019 The Khronos Group Inc. All Rights Reserved. This specification is protected by copyright laws and contains material proprietary to the Khronos Group, Inc. It or any components may not be reproduced, republished, distributed, transmitted, displayed, broadcast, or otherwise exploited in any manner without the express prior written permission of Khronos Group. You may use this specification for implementing the functionality therein, without altering or removing any trademark, copyright or other notice from the specification, but the receipt or possession of this specification does not convey any rights to reproduce, disclose, or distribute its contents, or to manufacture, use, or sell anything that it may describe, in whole or in part. 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All other product names, trademarks, and/or company names are used solely for identification and belong to their respective owners. 2 / 207 Revision number Date Release Info Author 0.1 Jan 2015 Initial sharing AG 0.2 Feb 2015 Added clarification, tables, examples AG 0.3 Feb 2015 Further cleanup AG 0.4 Apr 2015 Channel ordering standardized AG 0.5 Apr 2015 Typos and clarification AG 1.0 May 2015 Submission for 1.0 release AG 1.0 rev 2 Jun 2015 Clarifications for 1.0 release AG 1.0 rev 3 Jul 2015 Added KHR_DF_SAMPLE_DATATYPE_LINEAR AG 1.0 rev 4 Jul 2015 Clarified KHR_DF_SAMPLE_DATATYPE_LINEAR AG 1.0 rev 5 Mar 2019 Clarification and typography AG 1.1 Nov 2015 Added definitions of compressed texture formats AG 1.1 rev 2 Jan 2016 Added definitions of floating point formats AG 1.1 rev 3 Feb 2016 Fixed typo in sRGB conversion (thank you, Tom Grim!) AG 1.1 rev 4 Mar 2016 Fixed typo/clarified sRGB in ASTC, typographical improvements AG 1.1 rev 5 Mar 2016 Switch to official Khronos logo, removed scripts, restored title AG 1.1 rev 6 Jun 2016 ASTC "block footprint" note, fixed credits/changelog/contents AG 1.1 rev 7 Sep 2016 ASTC multi-point "part" and quint decode typo fixes AG 1.1 rev 8 Jun 2017 ETC2 legibility and table typo fix AG 1.1 rev 9 Mar 2019 Typo fixes and much reformatting AG 1.2 rev 0 Sep 2017 Added color conversion formulae and extra options AG 1.2 rev 1 Mar 2019 Typo fixes and much reformatting AG 3 / 207 Contents 1 Introduction 3 2 Overview 4 2.1 Glossary . .5 3 Required concepts not in the “format”8 4 Translation to API-specific representations 10 5 Data format descriptor 11 6 Descriptor block 12 7 Khronos Basic Data Format Descriptor Block 14 7.1 vendorId ................................................... 15 7.2 descriptorType ................................................ 15 7.3 versionNumber ............................................... 15 7.4 descriptorBlockSize ............................................. 15 7.5 colorModel ................................................. 16 7.5.1 KHR_DF_MODEL_UNSPECIFIED (=0) ............................ 16 7.5.2 KHR_DF_MODEL_RGBSDA (=1) ................................ 16 7.5.3 KHR_DF_MODEL_YUVSDA (=2) ................................ 17 7.5.4 KHR_DF_MODEL_YIQSDA (=3) ................................ 17 7.5.5 KHR_DF_MODEL_LABSDA (=4) ................................ 18 7.5.6 KHR_DF_MODEL_CMYKA (=5) ................................. 18 7.5.7 KHR_DF_MODEL_XYZW (=6).................................. 18 7.5.8 KHR_DF_MODEL_HSVA_ANG (=7)............................... 19 7.5.9 KHR_DF_MODEL_HSLA_ANG (=8)............................... 19 7.5.10 KHR_DF_MODEL_HSVA_HEX (=9)............................... 20 7.5.11 KHR_DF_MODEL_HSLA_HEX (= 10) . 20 7.5.12 KHR_DF_MODEL_YCGCOA (= 11) . 20 7.5.13 KHR_DF_MODEL_YCCBCCRC (= 12) . 21 7.5.14 KHR_DF_MODEL_ICTCP (= 13) . 21 7.5.15 KHR_DF_MODEL_CIEXYZ (= 14) . 22 7.5.16 KHR_DF_MODEL_CIEXYY (= 15) . 22 7.6 colorModel for compressed formats . 23 7.6.1 KHR_DF_MODEL_DXT1A/KHR_DF_MODEL_BC1A (= 128) . 23 7.6.2 KHR_DF_MODEL_DXT2/3/KHR_DF_MODEL_BC2 (= 129) . 23 7.6.3 KHR_DF_MODEL_DXT4/5/KHR_DF_MODEL_BC3 (= 130) . 23 7.6.4 KHR_DF_MODEL_BC4 (= 131) . 23 4 / 207 7.6.5 KHR_DF_MODEL_BC5 (= 132) . 23 7.6.6 KHR_DF_MODEL_BC6H (= 133) . 23 7.6.7 KHR_DF_MODEL_BC7 (= 134) . 24 7.6.8 KHR_DF_MODEL_ETC1 (= 160) . 24 7.6.9 KHR_DF_MODEL_ETC2 (= 161) . 24 7.6.10 KHR_DF_MODEL_ASTC (= 162) . 24 7.7 colorPrimaries ................................................ 25 7.7.1 KHR_DF_PRIMARIES_UNSPECIFIED (= 0) . 25 7.7.2 KHR_DF_PRIMARIES_BT709 (=1).............................. 25 7.7.3 KHR_DF_PRIMARIES_BT601_EBU (=2)........................... 25 7.7.4 KHR_DF_PRIMARIES_BT601_SMPTE (= 3) . 25 7.7.5 KHR_DF_PRIMARIES_BT2020 (=4) ............................. 25 7.7.6 KHR_DF_PRIMARIES_CIEXYZ (=5) ............................. 25 7.7.7 KHR_DF_PRIMARIES_ACES (=6)............................... 26 7.7.8 KHR_DF_PRIMARIES_ACESCC (=7) ............................. 26 7.7.9 KHR_DF_PRIMARIES_NTSC1953 (=8)............................ 26 7.7.10 KHR_DF_PRIMARIES_PAL525 (=9) ............................. 26 7.7.11 KHR_DF_PRIMARIES_DISPLAYP3 (= 10) . 26 7.7.12 KHR_DF_PRIMARIES_ADOBERGB (= 11) . 26 7.8 transferFunction .............................................. 27 7.8.1 KHR_DF_TRANSFER_UNSPECIFIED (= 0) . 27 7.8.2 KHR_DF_TRANSFER_LINEAR (=1).............................. 27 7.8.3 KHR_DF_TRANSFER_SRGB (=2)................................ 27 7.8.4 KHR_DF_TRANSFER_ITU (=3) ................................ 27 7.8.5 KHR_DF_TRANSFER_NTSC (=4)................................ 27 7.8.6 KHR_DF_TRANSFER_SLOG (=5)................................ 28 7.8.7 KHR_DF_TRANSFER_SLOG2 (=6)............................... 28 7.8.8 KHR_DF_TRANSFER_BT1886 (=7).............................. 28 7.8.9 KHR_DF_TRANSFER_HLG_OETF (=8) ............................ 28 7.8.10 KHR_DF_TRANSFER_HLG_EOTF (=9) ............................ 28 7.8.11 KHR_DF_TRANSFER_PQ_EOTF (= 10) . 28 7.8.12 KHR_DF_TRANSFER_PQ_OETF (= 11) . 28 7.8.13 KHR_DF_TRANSFER_DCIP3 (= 12) . 28 7.8.14 KHR_DF_TRANSFER_PAL_OETF (= 13) . 28 7.8.15 KHR_DF_TRANSFER_PAL625_EOTF (= 14) . 28 7.8.16 KHR_DF_TRANSFER_ST240 (= 15) . 28 7.8.17 KHR_DF_TRANSFER_ACESCC (= 16) . 29 7.8.18 KHR_DF_TRANSFER_ACESCCT (= 17) . 29 7.8.19 KHR_DF_TRANSFER_ADOBERGB (= 18) . 29 7.9 flags ..................................................... 29 7.9.1 KHR_DF_FLAG_ALPHA_PREMULTIPLIED (= 1) . 29 7.10 texelBlockDimension[0..3] ......................................... 30 7.11 bytesPlane[0..7] ............................................... 31 7.12 Sample information . 32 7.12.1 bitOffset .............................................. 32 7.12.2 bitLength ............................................. 32 7.12.3 channelType ............................................ 33 7.12.4 samplePosition[0..3] ....................................... 33 7.12.5 sampleLower ........................................... 34 7.12.6 sampleUpper ........................................... 35 5 / 207 8 Extension for more complex formats 36 9 Frequently Asked Questions 38 9.1 Why have a binary format rather than a human-readable one? . 38 9.2 Why not use an existing representation