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fellatio korisu korisuya maid monochrome penis

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The left panel said:
# Download larger version (3.4 MB JPG)
# Download PNG (844.4 KB)
.JPG even larger than .PNG?
PNG can adapt it's pallet to a 8bit instead of 24.
It also saves space by just using a sort of 'see above' when a section is the same as above, eg. the white areas.
That's why monochrome should always try and be PNG - lossless, and more compressed.