Old-style JPEG compression as described in section 22 of the TIFF 6.0 Specification is not supported.
The CCITT compression types are applicable to bilevel (1-bit) images only. The JPEG compression type is applicable to byte grayscale (1-band) and RGB (3-band) images only.
ZLib and Deflate compression are identical except for the value of the TIFF Compression field: for ZLib the Compression field has value 8 whereas for Deflate it has value 32946 (0x80b2). In both cases each image segment (strip or tile) is written as a single complete zlib data stream.
"EXIF JPEG" is a compression type used when writing the contents of an APP1 EXIF marker segment for inclusion in a JPEG native image metadata tree. The contents appended to the output when this compression type is used are a function of whether an empty or non-empty image is written. If the image is empty, then a TIFF IFD adhering to the specification of a compressed EXIF primary IFD is appended. If the image is non-empty, then a complete IFD and image adhering to the specification of a compressed EXIF thumbnail IFD and image are appended. Note that the data of the empty image may not later be appended using the pixel replacement capability of the TIFF writer.
If ZLib/Deflate or JPEG compression is used, the compression quality may be set. For ZLib/Deflate the supplied floating point quality value is rescaled to the range [1, 9] and truncated to an integer to derive the Deflate compression level. For JPEG the floating point quality value is passed directly to the JPEG writer plug-in which interprets it in the usual way.
The canWriteTiles and canWriteCompressed methods will return true; the canOffsetTiles and canWriteProgressive methods will return false.
If tiles are being written, then each of their dimensions will be rounded to the nearest multiple of 16 per the TIFF specification. If JPEG-in-TIFF compression is being used, and tiles are being written each tile dimension will be rounded to the nearest multiple of 8 times the JPEG minimum coded unit (MCU) in that dimension. If JPEG-in-TIFF compression is being used and strips are being written, the number of rows per strip is rounded to a multiple of 8 times the maximum MCU over both dimensions.
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