3 ms·
Yes, but variable-blocksize DCT is definitely used in the lossy modes (not sure about lossless).
by aidenn0 2y ago
Yes, but variable-blocksize DCT is definitely used in the lossy modes (not sure about lossless).
- edflsafoiewq 2y agoYeah, JPEG uses the DCT, so JPEG XL needs it too to be a superset.
- aidenn0 2y agoYes, but if the DCT were purely vestigial, then: 1. It wouldn't have support for DCTs not in JPEG. 2. It wouldn't use the DCT in its lossy-compression of photographic content if another transform was considered significantly better. Perhaps one could argue that they didn't want to add extra transforms, but they do use a modified Haar transform for e.g. synthetic content and alpha channels.
- lifthrasiir 2y agoThe squeeze transform used for extra progressive decoding is effectively a modified Haar transform.