transparency chunk
This commit is contained in:
Ryan Oldenburg
parent
c0803c3336
commit
5f7908f8a4
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@ -7,7 +7,7 @@ const
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type
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ChunkCounts = object
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PLTE, IDAT: uint8
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PLTE, IDAT, tRNS: uint8
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PngHeader = object
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width, height: int
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@ -146,7 +146,9 @@ proc unfilter(
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result[unfiteredIdx(x, y)] = value
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proc parseImageData(
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header: PngHeader, palette: seq[array[3, uint8]], data: seq[uint8]
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header: PngHeader,
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palette: seq[array[3, uint8]],
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transparency, data: seq[uint8]
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): seq[ColorRGBA] =
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result.setLen(header.width * header.height)
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@ -178,6 +180,7 @@ proc parseImageData(
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case header.colorType:
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of 0:
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let special = if transparency.len == 2: transparency[1].int else: -1
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var bytePos, bitPos: int
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for y in 0 ..< header.height:
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for x in 0 ..< header.width:
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@ -204,8 +207,9 @@ proc parseImageData(
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inc bytePos
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bitPos = 0
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let alpha = if value.int == special: 0 else: 255
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result[x + y * header.width] = ColorRGBA(
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r: value, g: value, b: value, a: 255
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r: value, g: value, b: value, a: alpha.uint8
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)
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# If we move to a new row, skip to the next full byte
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@ -213,13 +217,21 @@ proc parseImageData(
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inc bytePos
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bitPos = 0
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of 2:
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let special =
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if transparency.len == 6:
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ColorRGBA(
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r: transparency[1], g: transparency[3], b: transparency[5], a: 255
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)
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else:
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ColorRGBA()
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var bytePos: int
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for y in 0 ..< header.height:
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for x in 0 ..< header.width:
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let rgb = cast[ptr array[3, uint8]](unfiltered[bytePos].unsafeAddr)[]
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result[x + y * header.width] = ColorRGBA(
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r: rgb[0], g: rgb[1], b: rgb[2], a: 255
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)
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var rgba = ColorRGBA(r: rgb[0], g: rgb[1], b: rgb[2], a: 255)
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if rgba == special:
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rgba.a = 0
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result[x + y * header.width] = rgba
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bytePos += 3
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of 3:
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var bytePos, bitPos: int
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@ -247,9 +259,15 @@ proc parseImageData(
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if value.int >= palette.len:
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failInvalid()
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let rgb = palette[value]
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let
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rgb = palette[value]
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transparency =
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if transparency.len > value.int:
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transparency[value]
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else:
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255
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result[x + y * header.width] = ColorRGBA(
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r: rgb[0], g: rgb[1], b: rgb[2], a: 255
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r: rgb[0], g: rgb[1], b: rgb[2], a: transparency
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)
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# If we move to a new row, skip to the next full byte
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@ -297,7 +315,7 @@ proc decodePng*(data: seq[uint8]): Image =
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counts = ChunkCounts()
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header: PngHeader
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palette: seq[array[3, uint8]]
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imageData: seq[uint8]
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transparency, imageData: seq[uint8]
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prevChunkType: string
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# First chunk must be IHDR
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@ -333,9 +351,26 @@ proc decodePng*(data: seq[uint8]): Image =
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failInvalid()
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of "PLTE":
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inc counts.PLTE
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if counts.PLTE > 1 or counts.IDAT > 0:
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if counts.PLTE > 1 or counts.IDAT > 0 or counts.tRNS > 0:
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failInvalid()
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palette = parsePalette(data[pos ..< pos + chunkLen])
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of "tRNS":
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inc counts.tRNS
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if counts.tRNS > 1 or counts.IDAT > 0:
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failInvalid()
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transparency = data[pos ..< pos + chunkLen]
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case header.colorType:
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of 0:
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if transparency.len != 2:
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failInvalid()
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of 2:
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if transparency.len != 6:
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failInvalid()
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of 3:
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if transparency.len > palette.len:
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failInvalid()
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else:
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failInvalid()
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of "IDAT":
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inc counts.IDAT
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if counts.IDAT > 1 and prevChunkType != "IDAT":
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@ -372,7 +407,7 @@ proc decodePng*(data: seq[uint8]): Image =
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result = Image()
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result.width = header.width
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result.height = header.height
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result.data = parseImageData(header, palette, imageData)
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result.data = parseImageData(header, palette, transparency, imageData)
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proc decodePng*(data: string): Image {.inline.} =
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decodePng(cast[seq[uint8]](data))
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@ -73,6 +73,109 @@ const
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"s39n3p04", # 39x39 paletted file, no interlacing
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# "s40i3p04", # 40x40 paletted file, interlaced
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"s40n3p04", # 40x40 paletted file, no interlacing
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# "bgai4a08", # 8 bit grayscale, alpha, no background chunk, interlaced
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# "bgai4a16", # 16 bit grayscale, alpha, no background chunk, interlaced
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"bgan6a08", # 3x8 bits rgb color, alpha, no background chunk
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# "bgan6a16", # 3x16 bits rgb color, alpha, no background chunk
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"bgbn4a08", # 8 bit grayscale, alpha, black background chunk
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# "bggn4a16", # 16 bit grayscale, alpha, gray background chunk
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"bgwn6a08", # 3x8 bits rgb color, alpha, white background chunk
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# "bgyn6a16", # 3x16 bits rgb color, alpha, yellow background chunk
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# "tbbn0g04", # transparent, black background chunk
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# # "tbbn2c16", # transparent, blue background chunk
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"tbbn3p08", # transparent, black background chunk
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# # "tbgn2c16", # transparent, green background chunk
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"tbgn3p08", # transparent, light-gray background chunk
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"tbrn2c08", # transparent, red background chunk
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# # "tbwn0g16", # transparent, white background chunk
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"tbwn3p08", # transparent, white background chunk
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"tbyn3p08", # transparent, yellow background chunk
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"tp0n0g08", # not transparent for reference (logo on gray)
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"tp0n2c08", # not transparent for reference (logo on gray)
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"tp0n3p08", # not transparent for reference (logo on gray)
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"tp1n3p08", # transparent, but no background chunk
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"tm3n3p02", # multiple levels of transparency, 3 entries
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# "g03n0g16", # grayscale, file-gamma = 0.35
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"g03n2c08", # color, file-gamma = 0.35
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"g03n3p04", # paletted, file-gamma = 0.35
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# "g04n0g16", # grayscale, file-gamma = 0.45
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"g04n2c08", # color, file-gamma = 0.45
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"g04n3p04", # paletted, file-gamma = 0.45
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# "g05n0g16", # grayscale, file-gamma = 0.55
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"g05n2c08", # color, file-gamma = 0.55
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"g05n3p04", # paletted, file-gamma = 0.55
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# "g07n0g16", # grayscale, file-gamma = 0.70
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"g07n2c08", # color, file-gamma = 0.70
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"g07n3p04", # paletted, file-gamma = 0.70
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# "g10n0g16", # grayscale, file-gamma = 1.00
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"g10n2c08", # color, file-gamma = 1.00
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"g10n3p04", # paletted, file-gamma = 1.00
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# "g25n0g16", # grayscale, file-gamma = 2.50
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"g25n2c08", # color, file-gamma = 2.50
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"g25n3p04", # paletted, file-gamma = 2.50
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"f00n0g08", # grayscale, no interlacing, filter-type 0
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"f00n2c08", # color, no interlacing, filter-type 0
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"f01n0g08", # grayscale, no interlacing, filter-type 1
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"f01n2c08", # color, no interlacing, filter-type 1
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"f02n0g08", # grayscale, no interlacing, filter-type 2
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"f02n2c08", # color, no interlacing, filter-type 2
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"f03n0g08", # grayscale, no interlacing, filter-type 3
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"f03n2c08", # color, no interlacing, filter-type 3
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"f04n0g08", # grayscale, no interlacing, filter-type 4
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"f04n2c08", # color, no interlacing, filter-type 4
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"f99n0g04", # bit-depth 4, filter changing per scanline
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# "pp0n2c16", # six-cube palette-chunk in true-color image
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"pp0n6a08", # six-cube palette-chunk in true-color+alpha image
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"ps1n0g08", # six-cube suggested palette (1 byte) in grayscale image
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# "ps1n2c16", # six-cube suggested palette (1 byte) in true-color image
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"ps2n0g08", # six-cube suggested palette (2 bytes) in grayscale image
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# "ps2n2c16", # six-cube suggested palette (2 bytes) in true-color image
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"ccwn2c08", # chroma chunk w:0.3127,0.3290 r:0.64,0.33 g:0.30,0.60 b:0.15,0.06
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"ccwn3p08", # chroma chunk w:0.3127,0.3290 r:0.64,0.33 g:0.30,0.60 b:0.15,0.06
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"cdfn2c08", # physical pixel dimensions, 8x32 flat pixels
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"cdhn2c08", # physical pixel dimensions, 32x8 high pixels
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"cdsn2c08", # physical pixel dimensions, 8x8 square pixels
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"cdun2c08", # physical pixel dimensions, 1000 pixels per 1 meter
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"ch1n3p04", # histogram 15 colors
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"ch2n3p08", # histogram 256 colors
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"cm0n0g04", # modification time, 01-jan-2000 12:34:56
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"cm7n0g04", # modification time, 01-jan-1970 00:00:00
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"cm9n0g04", # modification time, 31-dec-1999 23:59:59
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# "cs3n2c16", # color, 13 significant bits
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"cs3n3p08", # paletted, 3 significant bits
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"cs5n2c08", # color, 5 significant bits
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"cs5n3p08", # paletted, 5 significant bits
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"cs8n2c08", # color, 8 significant bits (reference)
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"cs8n3p08", # paletted, 8 significant bits (reference)
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"ct0n0g04", # no textual data
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"ct1n0g04", # with textual data
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"ctzn0g04", # with compressed textual data
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"cten0g04", # international UTF-8, english
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"ctfn0g04", # international UTF-8, finnish
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"ctgn0g04", # international UTF-8, greek
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"cthn0g04", # international UTF-8, hindi
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"ctjn0g04", # international UTF-8, japanese
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"exif2c08", # chunk with jpeg exif data
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# "oi1n0g16", # grayscale mother image with 1 idat-chunk
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# "oi1n2c16", # color mother image with 1 idat-chunk
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# "oi2n0g16", # grayscale image with 2 idat-chunks
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# "oi2n2c16", # color image with 2 idat-chunks
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# "oi4n0g16", # grayscale image with 4 unequal sized idat-chunks
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# "oi4n2c16", # color image with 4 unequal sized idat-chunks
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# "oi9n0g16", # grayscale image with all idat-chunks length one
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# "oi9n2c16", # color image with all idat-chunks length one
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"z00n2c08", # color, no interlacing, compression level 0 (none)
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"z03n2c08", # color, no interlacing, compression level 3
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"z06n2c08", # color, no interlacing, compression level 6 (default)
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"z09n2c08", # color, no interlacing, compression level 9 (maximum)
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]
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pngSuiteCorruptedFiles* = [
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