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devongovett / png-stream

A streaming PNG encoder and decoder
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Default previous scanline to all zeros on the first scanline #4

Closed devongovett closed 7 years ago

devongovett commented 7 years ago

See http://www.w3.org/TR/PNG/#9Filters.

For filters that refer to the prior scanline, the entire prior scanline and bytes "to the left of" the first pixel in the prior scanline shall be treated as being zeroes for the first scanline of a reduced image.