reverse-png-filter ( lines n -- byte-array )


Vocabulary
images.png

Inputs
linesan object
nan object


Outputs
byte-arrayan object


Definition
USING: arrays grouping kernel math sequences ;

IN: images.png

:: reverse-png-filter ( lines n -- byte-array )
lines dup first length 0 <array> prefix
[ n 1 - 0 <array> prepend ] map 2 clump [
n swap first2
[ ] [ n 1 - swap nth ] [ [ 0 n 1 - ] dip set-nth ] tri
png-unfilter-line
] map B{ } concat-as ;