ImageSharp/src/ImageSharp/Formats/Tiff/README.md

ImageSharp TIFF codec

References

• TIFF

  • TIFF 6.0 Specification,(http://www.npes.org/pdf/TIFF-v6.pdf)
  • TIFF Supplement 1
  • TIFF Supplement 2
  • TIFF Supplement 3
  • TIFF-F/FX Extension (RFC2301)
  • TIFF/EP Extension (Wikipedia)
  • Adobe TIFF Pages
  • Unofficial TIFF FAQ
  • CCITT T.4 Compression
  • CCITT T.6 Compression

• DNG

  • Adobe DNG Pages

• Metadata (EXIF)

  • EXIF 2.3 Specification

• Metadata (XMP)

  • Adobe XMP Pages
  • Adobe XMP Developer Center

Implementation Status

• The Decoder currently only supports decoding multiframe images, which have the same dimensions.
• Some compression formats are not yet supported. See the list below.

Deviations from the TIFF spec (to be fixed)

• Decoder
  • A Baseline TIFF reader must skip over extra components (e.g. RGB with 4 samples per pixels)
    • NB: Need to handle this for both planar and chunky data
  • If the SampleFormat field is present and not 1 - fail gracefully if you cannot handle this
  • Compression=None should treat 16/32-BitsPerSample for all samples as SHORT/LONG (for byte order and padding rows)
  • Check Planar format data - is this encoded as strips in order RGBRGBRGB or RRRGGGBBB?

Compression Formats

	Encoder	Decoder	Comments
None	Y	Y
Ccitt1D	Y	Y
PackBits	Y	Y
CcittGroup3Fax	Y	Y
CcittGroup4Fax	Y	Y
Lzw	Y	Y	Based on ImageSharp GIF LZW implementation - this code could be modified to be (i) shared, or (ii) optimised for each case
Old Jpeg			We should not even try to support this
Jpeg (Technote 2)	Y	Y
Deflate (Technote 2)	Y	Y	Based on PNG Deflate.
Old Deflate (Technote 2)		Y

Photometric Interpretation Formats

	Encoder	Decoder	Comments
WhiteIsZero	Y	Y	General + 1/4/8-bit optimised implementations
BlackIsZero	Y	Y	General + 1/4/8-bit optimised implementations
Rgb (Chunky)	Y	Y	General + Rgb888 optimised implementation
Rgb (Planar)		Y	General implementation only
PaletteColor	Y	Y	General implementation only
TransparencyMask
Separated (TIFF Extension)
YCbCr (TIFF Extension)		Y
CieLab (TIFF Extension)
IccLab (TechNote 1)

Baseline TIFF Tags

	Encoder	Decoder	Comments
NewSubfileType
SubfileType
ImageWidth	Y	Y
ImageLength	Y	Y
BitsPerSample	Y	Y
Compression	Y	Y
PhotometricInterpretation	Y	Y
Thresholding
CellWidth
CellLength
FillOrder		Y
ImageDescription	Y	Y
Make	Y	Y
Model	Y	Y
StripOffsets	Y	Y
Orientation		-	Ignore. Many readers ignore this tag.
SamplesPerPixel	Y	-	Currently ignored, as can be inferred from count of BitsPerSample
RowsPerStrip	Y	Y
StripByteCounts	Y	Y
MinSampleValue
MaxSampleValue
XResolution	Y	Y
YResolution	Y	Y
PlanarConfiguration		Y	Encoding support only chunky.
FreeOffsets
FreeByteCounts
GrayResponseUnit
GrayResponseCurve
ResolutionUnit	Y	Y
Software	Y	Y
DateTime	Y	Y
Artist	Y	Y
HostComputer	Y	Y
ColorMap	Y	Y
ExtraSamples		(Y)	Only UnassociatedAlphaData is supported so far
Copyright	Y	Y

Extension TIFF Tags

	Encoder	Decoder	Comments
NewSubfileType
DocumentName	Y	Y
PageName
XPosition
YPosition
T4Options		Y
T6Options
PageNumber
TransferFunction
Predictor	Y	Y	only Horizontal
WhitePoint
PrimaryChromaticities
HalftoneHints
TileWidth		-
TileLength		-
TileOffsets		-
TileByteCounts		-
BadFaxLines
CleanFaxData
ConsecutiveBadFaxLines
SubIFDs		-
InkSet
InkNames
NumberOfInks
DotRange
TargetPrinter
SampleFormat		-
SMinSampleValue
SMaxSampleValue
TransferRange
ClipPath
XClipPathUnits
YClipPathUnits
Indexed
JPEGTables
OPIProxy
GlobalParametersIFD
ProfileType
FaxProfile
CodingMethods
VersionYear
ModeNumber
Decode
DefaultImageColor
JPEGProc
JPEGInterchangeFormat
JPEGInterchangeFormatLength
JPEGRestartInterval
JPEGLosslessPredictors
JPEGPointTransforms
JPEGQTables
JPEGDCTables
JPEGACTables
YCbCrCoefficients		Y
YCbCrSubSampling		Y
YCbCrPositioning
ReferenceBlackWhite		Y
StripRowCounts	-	-	See RFC 2301 (File Format for Internet Fax).
XMP	Y	Y
ImageID
ImageLayer

Private TIFF Tags

	Encoder	Decoder	Comments
Wang Annotation
MD FileTag
MD ScalePixel
MD ColorTable
MD LabName
MD SampleInfo
MD PrepDate
MD PrepTime
MD FileUnits
ModelPixelScaleTag
IPTC	Y	Y
INGR Packet Data Tag
INGR Flag Registers
IrasB Transformation Matrix
ModelTiepointTag
ModelTransformationTag
Photoshop
Exif IFD		-	0x8769 SubExif
ICC Profile	Y	Y
GeoKeyDirectoryTag
GeoDoubleParamsTag
GeoAsciiParamsTag
GPS IFD
HylaFAX FaxRecvParams
HylaFAX FaxSubAddress
HylaFAX FaxRecvTime
ImageSourceData
Interoperability IFD
GDAL_METADATA
GDAL_NODATA
Oce Scanjob Description
Oce Application Selector
Oce Identification Number
Oce ImageLogic Characteristics
DNGVersion
DNGBackwardVersion
UniqueCameraModel
LocalizedCameraModel
CFAPlaneColor
CFALayout
LinearizationTable
BlackLevelRepeatDim
BlackLevel
BlackLevelDeltaH
BlackLevelDeltaV
WhiteLevel
DefaultScale
DefaultCropOrigin
DefaultCropSize
ColorMatrix1
ColorMatrix2
CameraCalibration1
CameraCalibration2
ReductionMatrix1
ReductionMatrix2
AnalogBalance
AsShotNeutral
AsShotWhiteXY
BaselineExposure
BaselineNoise
BaselineSharpness
BayerGreenSplit
LinearResponseLimit
CameraSerialNumber
LensInfo
ChromaBlurRadius
AntiAliasStrength
DNGPrivateData
MakerNoteSafety
CalibrationIlluminant1
CalibrationIlluminant2
BestQualityScale
Alias Layer Metadata