View source for Fixing DXT Green Tint Compression

[[File:DXT compression demo.jpg|thumb|right|300px|Original texture (left) versus a re-converted, untreated copy (right), demonstrating the effects of DXT compression.]]
In the {{src|2|nt=1}}, textures are stored using the Valve Texture Format (VTF), which can store image data in a great variety of formats. The most common and standard ones are the lossy and compression-based DXT1 (used for textures with no alpha channel) and DXT5 (used for textures with an alpha channel). 

However, when a VTF file with DXT compression is viewed or extracted using {{VTFEdit|2}} (which also seems to affects {{ps|1}}'s VTF plug-in), a slightly green-tinted output is generated, due to issues with VTFEdit DXT decoder. This doesn't affect the VTFEdit DXT encoder (used to encode VTFs from [[TGA]]/[[PNG]]/other raster image formats). Usually, this altered result would merit no tampering. However, if a project requires both a texture and a modified version to be side by side, differences will inevitably become evident, calling for a workaround to be implemented.

The proper solution is to use {{vtfeditreloaded|2}}, which fixes the green tint issue when viewing or extracting texture. Another solution would be to store the texture using a different format, such as an uncompressed and, therefore, lossless one, like BGR888 or BGRA8888. However, these formats will considerably increase file size and VRAM usage.

==Fixing green tint issues==
# Open the original texture in the image editor of your choice.
# Create a blank layer with alpha channel support on top of the original texture.
# Bucket-fill the new layer with RGB 7 3 7 (HTML notation #070307).
# Copy the original texture and paste it into the alpha channel of the new layer.
# Set the layer mode to Legacy Addition (GIMP),<sup>[1]</sup> Linear Dodge (Add) (Photoshop) or the equivalent addition-based blend mode of your editor.
# Flatten the image if the texture has no transparency. Otherwise, merge all visible layers.
# Export as TGA and convert to VTF using {{Vtfeditreloaded|4}}. For the image data format, use either DXT1 or DXT5, depending on your source material.

===Footnotes===
# For GIMP 2.10, the entire program was ported to the GEGL image processing library, which is based around linear RGB color space as opposed to gamma-corrected (perceptual) RGB color space, which modifies the behavior of several blending modes. This is why switching blending modes from Normal to Legacy is required; for pre-2.10 backwards compatibility.

==See also==
* [[Restoring Texture After DXT Compression]]

[[Category:Material System]]
[[Category:Technical]]
[[Category:Tutorials]]