> PNG filters each horizontal line of the image data before running it through Deflate, with a pre-processing step. Yes, as a means of making the data fed into

> PNG filters each horizontal line of the image data before running it through Deflate, with a pre-processing step. Yes, as a means of making the data fed into the compressor repetitive enough to benefit from the compression algorithm. > So, no, a general purpose compression algorithm isn't very good for image data on its own. That's not what I said.