Android version 2.2 (Froyo) includes support for ETC1. The ‘ETC2’ scheme expands ETC1 in a backwards-compatible way to provide higher quality RGB compression, as well as compression of RGBA (RGB plus alpha), single channel (R11) and dual channel (RG11) data. The following ETC2 codecs are mandatory in OpenGL ES 3.0 and OpenGL 4.3:
What is ETC2 in OpenGL?
The ‘ETC2’ scheme expands ETC1 in a backwards-compatible way to provide higher quality RGB compression, as well as compression of RGBA (RGB plus alpha), single channel (R11) and dual channel (RG11) data. The following ETC2 codecs are mandatory in OpenGL ES 3.0 and OpenGL 4.3:
What is etc compression?
The original specification of ETC compression is based on an older compression format called PACKMAN, and was originally called iPACKMAN (improved PACKMAN). This was later renamed to ETC, and when the specification was updated to ETC2, the original ETC became ETC1. ETC1 is actually pretty simple in its format.
What is etetc texture compression?
ETC (Ericsson Texture Compression) is a texture compression format originally designed on the principal that the Human ocular system (your eyes) is much more perceptive to differences in luminance (brightness) than chrominance (color).
Does it support image compression with Alpha components?
It does not support the compression of images with Alpha components, although there are work-arounds for this. ETC1 takes 4×4 groups of pixel data and compresses each into a single 64-bit word.
What does GL_compressed_rgba8_etc2_EAC mean?
GL_COMPRESSED_RGBA8_ETC2_EAC — Compresses RGBA8888 data with full alpha support. GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2 — Compresses RGBA data where pixels are either fully transparent or fully opaque. sRGB variants of the above codecs are also available.
