User:SirYodaJedi/Image formats

For a Russian translation primarily by NOUG4AT, see User:SirYodaJedi/Image formats/ru.

This is an essay.
It contains the advice or opinions of one or more of the Valve Developer Community's contributors.
This page is not an encyclopedia article, nor is it one of the Valve Developer Community's policies or guidelines, as it has not been thoroughly vetted by the community.
Some essays represent widespread norms; others only represent minority viewpoints.

The following is a list of standard image formats, along with which engines support them, whether they are compressed, and when I recommend using them.

Important:These are subjective recomendations; do not move the page out of userspace! Instead, consider copying the objective segments to a new page.

Warning:I have not personally tested the any formats in or , as I don't have either available to test. I also have not tested IA88, A8, or BGRA16F. The information stated on this page regarding those is based upon conceptual knowledge of the formats and preexisting documentation regarding strata's VTF v7.6 and Source 2's VTEX formats.

	Supported in
Format	GoldSrc	Source	Strata	Source 2	Compressed?	Recommended usage
P8 (256-color)	Yes, except for main menu backgrounds and detail textures	No (use BGR565 or BGRA8888)	No (use BC7)	No (use BC7)	Yes, 1 palette for entire image with 256 colors	: Most textures (world, models, sprites, overviews, etc.)
BGR888, RGB888 (24-bit true color)	Limited; only for skyboxes, detail textures, main menu backgrounds, and VGUI elements	Yes	Yes	Yes	No (except in , see notes)	: Skyboxes, detail textures, main menu backgrounds, and VGUI elements : Skyboxes, low-res normal maps without an alpha channel, and colored textures wherein a significant portion is dark grey. and : Not recommended; use BC7 instead
BGRA8888, RGBA8888 (32-bit true color with translucency)	Limited; only for VGUI elements	Yes	Yes	Yes	No	: Densely detailed textures with alpha channels : Densely detailed low-res normal maps with specular mask via alpha channel ($normalmapalphaenvmapmask). + : Not recommended; use BC7 instead
BGRA8888, RGBA8888 (Source 1 Compressed HDR, aka "RGBM"; sky shaders only)	No	Yes	Yes	Yes	Yes; alpha channel used as a multiplicand rather than for translucency (see Valve Texture Format#HDR compression) Can also be combined used with DXT5, but doing so is not recommended.	: HDR skyboxes and : Not recommended; use BC6H instead
BGRA16161616F, RGBA16161616F (16 bpc Floating Point HDR with translucency)	No	Yes	Yes	Yes	No	, , : HDR textures with an alpha channel
BGR565 (16-bit color)	No	Yes	Yes	No (use BC7)	No	: Low-res normal maps without specular mask; : Densely detailed low-res textures without alpha channels : Not recommended; use BC7 instead
BGRA4444 (16-bit color with translucency)	No	Yes	Yes	No (use BC7)	No	: Not recommended; causes noticable color shift rendering it unable to convincingly portray a flat normal map. : Not recommended; use BC7 instead.
I8 (8-bit greyscale)	Technically (using P8)	Yes	Yes	Yes	No	: Specular masks for materials without a normal map (avoids DXTn green tint; same file size as DTX5). : Decals using DecalModulate (avoids DXTn green tint) +: Not recommended; use ATI1N instead
IA88 (8-bit greyscale with translucency)	No	Yes	Yes	Yes	No	: Greyscale decals with an alpha channel +: Not recommended; use BC7 instead
A8 (Translucency only)	Technically, only for sprites (using IndexAlpha) and decals	Yes	Yes	Yes	No	, , & : Single-color textures with an alpha channel (use material coloring to assign non-white colors)
DXT1 (AKA BC1)	(only in )	Yes	Yes	Yes	Yes; two explicit BGR565 colors and two interpolated colors per 4x4 block	, , & : Moderately detailed high-res textures with no alpha channel
DXT3 (AKA BC2)	No	Yes	Yes	No (use DXT5)	RGB only; RGB handled like DXT1, with uncompressed 4-bit alpha	, : Not recommended, use DXT5 instead
DXT5 (AKA BC3)	No	Yes	Yes	Yes	Yes; RGB handled like DXT1, with alpha handled like ATI1N	, , & : Moderately detailed high-res textures with an alpha channel
ATI1N (AKA BC4)	No	No (use I8)	Yes	Yes	Yes; four explicit I8 values and four interpolated values per 4x4 block	: Specular masks for materials without a normal map. : All Specular masks
ATI2N (AKA BC5)	No	No (use BGR565 if really necessary)	Yes	Yes	Yes; two independent ATI1N-style channels (red and green)	: $blendmodulatetexture, perhaps : ???
BC6H (AKA BC6)	No	No (use compressed BGRA8888)	Yes	Yes	Yes; four explicit RGB161616 or RGB161616F colors and four interpolated colors per 4x4 block	& : HDR skyboxes
BC7	No	No (use BGR565 or BGRA8888)	Yes	Yes	Yes; four explicit RGB888 or RGBA8888 colors and four interpolated colors per 4x4 block	& : Whenever DXT1 or DXT5 is too blocky and/or DXT green tint needs to be avoided.

Note:The Steam versions of support RLE-compressed TGA files for certain use cases, such as skyboxes and detail textures. Other use cases, such as taskbar icons or transparent VGUI sprites, do not support RLE compression.
Not all programs can export compressed TGAs; GIMP does this when exporting to TGA by default. Make sure that the origin is set to "bottom-left".

Note:All formats supported by can be compressed with PNG-style deflate compression, using its custom v7.6 VTF format. This is used in conjunction with whatever inherent GPU-supported compression format is being used; as such, it is not mentioned in this table.

Note:Although the VTF format used by supports encoding color channels in multiple orders (RGB, BGR, RGBA, BGRA, ARGB, ABGR), only BGR and BGRA are guaranteed to work correctly. By comparison, prefers RGB and RGBA, using its VTEX format.

Note:Additionally, formats with a 1-bit alpha channel, such as BGRA5551 or BGR888_BLUESCREEN are not as reliable as those with a 4-bit or 8-bit alpha channel, and will often treat the entire image as opaque, with the transparent pixels appearing as black.
Formats with 1-bit alpha should be avoided anyway (except in ), even when using $alphatest, as it will result in inaccurate transparency on mipmaps.

Note:, , and all support non-floating point HDR textures, however floating point is preferred, as it allows for better precision over the texture's brightness. VTEX defaults to floating point when using nocompress with pfm (see HDR Skybox Creation#Creating the Materials).