Paste: PNG reverse filter truecolor with alpha (hardcoded)
| Author: | klazuka |
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| Mode: | factor |
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| Date: | Mon, 28 Sep 2009 18:39:02 |
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Plain Text |
:: png-unfilter-line ( prev curr filter -- curr' )
prev :> c
prev 4 tail-slice :> b
curr :> a
curr 4 tail-slice :> x
x length [0,b)
filter {
{ filter-none [ drop ] }
{ filter-sub [ [| n | n x nth n a nth + 256 wrap n x set-nth ] each ] }
{ filter-up [ [| n | n x nth n b nth + 256 wrap n x set-nth ] each ] }
{ filter-average [ [| n | n x nth n a nth n b nth + 2/ + 256 wrap n x set-nth ] each ] }
{ filter-paeth [ [| n | n x nth n a nth n b nth n c nth paeth + 256 wrap n x set-nth ] each ] }
} case
curr 4 tail ;
: reverse-png-filter ( lines -- byte-array )
dup first length 0 <array> prefix
[ { 0 0 0 } prepend ] map
2 clump [
first2 dup [ fourth ] [ 0 swap set-fourth ] bi
png-unfilter-line
] map B{ } concat-as ;
| Author: | erg |
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| Mode: | factor |
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| Date: | Mon, 28 Sep 2009 19:00:07 |
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Plain Text |
:: png-unfilter-line ( width prev curr filter -- curr' )
prev :> c
prev width tail-slice :> b
curr :> a
curr width tail-slice :> x
x length [0,b)
filter {
{ filter-none [ drop ] }
{ filter-sub [ [| n | n x nth n a nth + 256 wrap n x set-nth ] each ] }
{ filter-up [ [| n | n x nth n b nth + 256 wrap n x set-nth ] each ] }
{ filter-average [ [| n | n x nth n a nth n b nth + 2/ + 256 wrap n x set-nth ] each ] }
{ filter-paeth [ [| n | n x nth n a nth n b nth n c nth paeth + 256 wrap n x set-nth ] each ] }
} case
curr width tail ;
:: reverse-png-filter ( n lines -- byte-array )
lines dup first length 0 <array> prefix
[ n 1 - 0 <array> prepend ] map
2 clump [
first2 [ [ n ] 2dip ] [ n 1 - swap nth ] [ [ 0 n 1 - ] dip set-nth ] tri
png-unfilter-line
] map B{ } concat-as ;
: png-image-bytes ( loading-png -- byte-array )
[ png-bytes-per-pixel ] [ inflate-data ] [ png-group-width ] tri group rever
se-png-filter ;
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