started tiff
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Ryan Oldenburg
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d662111f58
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266
src/pixie/fileformats/tiff.nim
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266
src/pixie/fileformats/tiff.nim
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import chroma, flatty/binny, pixie/common, pixie/images, pixie/internal
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const
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tiffSignatures* = [
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[0x4d.uint8, 0x4d, 0x00, 0x2a],
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[0x49.uint8, 0x49, 0x2a, 0x00]
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]
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knownTags = [
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0x0100.uint16, # ImageWidth
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0x0101, # ImageLength
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0x0102, # BitsPerSample
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0x0103, # Compression
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0x0106, # PhotometricInterpretation
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0x0111, # StripOffsets
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0x0116, # RowsPerStrip
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0x0117, # StripByteCounts
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0x0140, # ColorMap
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]
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type
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Tiff* = ref object
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width*, height*: int
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data*: seq[ColorRGBA]
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template failInvalid() =
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raise newException(PixieError, "Invalid TIFF buffer, unable to load")
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proc decodeTiff*(data: string): Tiff =
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if data.len < 8:
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failInvalid()
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result = Tiff()
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var
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pos: int
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isBigEndian: bool
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bitsPerSample: seq[int]
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compression: int
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photometricInterpretation: int
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stripOffsets, stripByteCounts: seq[int]
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rowsPerStrip: int
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colorMap: seq[ColorRGBA]
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let signature = cast[array[4, uint8]](data.readUint32(0))
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if signature == tiffSignatures[0]:
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isBigEndian = true
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elif signature == tiffSignatures[1]:
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discard
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else:
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failInvalid()
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pos = 4
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let ifdOffset = data.readUint32(pos).maybeSwap(isBigEndian).int
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pos = ifdOffset # Move to the first IFD offset
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if pos + 2 > data.len:
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failInvalid()
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let numEntries = data.readUint16(pos).maybeSwap(isBigEndian).int
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pos += 2
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for _ in 0 ..< numEntries:
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if pos + 12 > data.len:
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failInvalid()
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let
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tag = data.readUint16(pos + 0).maybeSwap(isBigEndian)
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fieldType = data.readUint16(pos + 2).maybeSwap(isBigEndian)
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numValues = data.readUint32(pos + 4).maybeSwap(isBigEndian).int
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valueOrOffset = pos + 8
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pos += 12
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if tag notin knownTags:
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continue
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let bytesPerValue =
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case fieldType:
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of 1:
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1
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of 2:
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1
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of 3:
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2
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of 4:
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4
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else:
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raise newException(PixieError, "Unsupported field type " & $fieldType)
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var valueOffset =
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if numValues * bytesPerValue <= 4:
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valueOrOffset
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else:
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data.readUint32(valueOrOffset).maybeSwap(isBigEndian).int
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proc readValue(offset: int): int =
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case fieldType:
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of 1:
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if offset + 1 > data.len:
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failInvalid()
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data.readUint8(offset).maybeSwap(isBigEndian).int
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of 3:
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if offset + 2 > data.len:
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failInvalid()
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data.readUint16(offset).maybeSwap(isBigEndian).int
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of 4:
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if offset + 4 > data.len:
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failInvalid()
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data.readUint32(offset).maybeSwap(isBigEndian).int
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else:
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raise newException(PixieError, "Unsupported field type " & $fieldType)
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case tag:
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of knownTags[0]:
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if numValues != 1:
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failInvalid()
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result.width = readValue(valueOffset)
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of knownTags[1]:
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if numValues != 1:
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failInvalid()
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result.height = readValue(valueOffset)
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of knownTags[2]:
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for _ in 0 ..< numValues:
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bitsPerSample.add(readValue(valueOffset))
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valueOffset += bytesPerValue
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of knownTags[3]:
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if numValues != 1:
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failInvalid()
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compression = readValue(valueOffset)
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of knownTags[4]:
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if numValues != 1:
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failInvalid()
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photometricInterpretation = readValue(valueOffset)
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of knownTags[5]:
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for _ in 0 ..< numValues:
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stripOffsets.add(readValue(valueOffset))
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valueOffset += bytesPerValue
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of knownTags[6]:
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if numValues != 1:
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failInvalid()
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rowsPerStrip = readValue(valueOffset)
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of knownTags[7]:
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for _ in 0 ..< numValues:
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stripByteCounts.add(readValue(valueOffset))
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valueOffset += bytesPerValue
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of knownTags[8]:
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if fieldType != 3:
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failInvalid()
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var values: seq[int]
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for _ in 0 ..< numValues:
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values.add(readValue(valueOffset))
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valueOffset += bytesPerValue
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colorMap.setLen(numValues div 3)
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for i in 0 ..< colorMap.len:
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colorMap[i] = rgba(
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((values[i].float32 / 65535) * 255).uint8,
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((values[i + colorMap.len].float32 / 65535) * 255).uint8,
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((values[i + 2 * colorMap.len].float32 / 65535) * 255).uint8,
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255
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)
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else:
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discard
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if result.width == 0 or result.height == 0:
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failInvalid()
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if stripOffsets.len != stripByteCounts.len:
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failInvalid()
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if bitsPerSample.len == 0:
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failInvalid()
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for i, bits in bitsPerSample:
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if bits notin {8}:
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raise newException(
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PixieError,
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"TIFF bits per sample of " & $bits & " not supported yet"
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)
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# Check the bits per sample are all equal
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for i in 0 ..< bitsPerSample.len:
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for j in 0 ..< bitsPerSample.len:
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if bitsPerSample[i] != bitsPerSample[j]:
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failInvalid()
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var decompressed: string
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case compression:
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of 1: # No compression
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var stripDataLen: int
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for byteCount in stripByteCounts:
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stripDataLen += byteCount
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decompressed.setLen(stripDataLen)
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var at: int
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for i, offset in stripOffsets:
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let byteCount = stripByteCounts[i]
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if offset + byteCount > data.len:
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failInvalid()
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copyMem(decompressed[at].addr, data[offset].unsafeAddr, byteCount)
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at += byteCount
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# of 5: # LZW
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else:
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raise newException(
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PixieError,
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"TIFF compression " & $compression & " not supported yet"
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)
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result.data.setLen(result.width * result.height)
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case photometricInterpretation:
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of 2: # RGB
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if bitsPerSample.len == 4: # 32 bit RGBA
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raise newException(PixieError, "RGBA TIFF not supported yet")
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elif bitsPerSample.len == 3: # 24 bit RGB
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if decompressed.len div 3 != result.data.len:
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failInvalid()
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for i in 0 ..< result.data.len:
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let decompressedIdx = i * 3
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result.data[i] = rgba(
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decompressed[decompressedIdx + 0].uint8,
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decompressed[decompressedIdx + 1].uint8,
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decompressed[decompressedIdx + 2].uint8,
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255
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)
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else:
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failInvalid()
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of 3: # Color Map
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if decompressed.len != result.data.len:
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failInvalid()
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for i in 0 ..< result.data.len:
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let colorMapIndex = decompressed[i].int
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if colorMapIndex > colorMap.len:
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failInvalid()
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result.data[i] = colorMap[colorMapIndex]
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else:
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raise newException(
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PixieError,
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"TIFF photometric interpretation " & $photometricInterpretation &
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" not supported yet"
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)
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proc newImage*(tiff: Tiff): Image =
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result = newImage(tiff.width, tiff.height)
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copyMem(result.data[0].addr, tiff.data[0].addr, tiff.data.len * 4)
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result.data.toPremultipliedAlpha()
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proc convertToImage*(tiff: Tiff): Image {.raises: [].} =
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## Converts a PNG into an Image by moving the data. This is faster but can
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## only be done once.
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type Movable = ref object
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width, height, channels: int
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data: seq[ColorRGBX]
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result = Image()
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result.width = tiff.width
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result.height = tiff.height
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result.data = move cast[Movable](tiff).data
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result.data.toPremultipliedAlpha()
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BIN
tests/fileformats/tiff/pc260001.tif
Normal file
BIN
tests/fileformats/tiff/pc260001.tif
Normal file
Binary file not shown.
6
tests/test_tiff.nim
Normal file
6
tests/test_tiff.nim
Normal file
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@ -0,0 +1,6 @@
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import pixie, pixie/fileformats/tiff
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let
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t = decodeTiff(readFile("tests/fileformats/tiff/pc260001.tif"))
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image = newImage(t)
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# image.writeFile("tests/fileformats/tiff/pc260001.png")
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