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@@ -118,7 +118,15 @@
`basisu -comp_level 2 x.png`
-To unpack a .basis file to multiple .png/.ktx files:
+In some rare images (ones with blue sky gradients come to bind), you may need to increase the ETC1S comp_level setting. This controls the amount of overall effort the encoder uses to optimize the codebooks (palettes) and compressed data stream. Higher comp_level's are significantly slower, and shouldn't be used unless necessary:
+
+`basisu -ktx2 x.png -comp_level 5 -q 255`
+
+### Unpacking .basis/.KTX2 files to .PNG/.KTX files
+
+You can either use the command line tool or [call the transcoder directly](https://github.com/BinomialLLC/basis_universal/wiki/How-to-Use-and-Configure-the-Transcoder) from JavaScript or C/C++ code to decompress .basis/.KTX2 files to GPU texture data or uncompressed images.
+
+To use the command line tool to unpack a .basis file to multiple .png/.ktx files:
`basisu x.basis`
@@ -132,7 +140,7 @@
After compression, the compressor transcodes all slices in the output .basis file to validate that the file decompresses correctly. It also validates all header, compressed data, and slice data CRC16's.
-For best quality, you must supply basisu with original uncompressed source images. Any other type of lossy compression applied before basisu (including ETC1/BC1-5, BC7, JPEG, etc.) will cause multi-generational artifacts to appear in the final output textures.
+For best quality, you must **supply basisu with original uncompressed source images**. Any other type of lossy compression applied before basisu (including ETC1/BC1-5, BC7, JPEG, etc.) will cause multi-generational artifacts to appear in the final output textures.
For the maximum possible achievable ETC1S mode quality with the current format and encoder (completely ignoring encoding speed!), use:
@@ -157,7 +165,7 @@
To control the ETC1S encoder's quality vs. encoding speed tradeoff, see [ETC1S Compression Effort Levels](https://github.com/BinomialLLC/basis_universal/wiki/ETC1S-Compression-Effort-Levels).
-### More detailed examples
+### More Examples
`basisu x.png`\
Compress sRGB image x.png to a ETC1S format x.basis file using default settings (multiple filenames OK). ETC1S format files are typically very small on disk (around .5-1.5 bits/texel).
