This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Block order in Theora superblock.svg Theora superblock showing the order of the coding of blocks within superblock which follows Hilbert curve Superblocks are made up by transform blocks blue which each cover samples Blocks are shown as blue squares block boundaries in green boundaries of areas represented by one sample in gray