etcpak strikes again, this time with version 0.5, which has the ability to calculate planar blocks from the ETC2 standard. Color gradients, which were a sore spot in the image quality previously, will now have a much smoother look. This new option is activated by passing -etc2 parameter and comes at a small time cost (152% of pure ETC1 mode, 77 ms vs 117 ms). Example compressed image:
Planar block count in this image is quite high, as can be seen on the following debug image, where blue color indicates planar mode:
It should be noted that AVX2 version of planar block compression does not produce the same results as scalar one. Keep that in mind on pre-Haswell machines.