A subclass of
ImageWriteParam ImageWriteParam allowing control over the TIFF writing process. The set of innately
supported compression types is listed in the following table:
Supported Compression Types
| Compression Type | Description | Reference |
|---|
| CCITT RLE |
Modified Huffman compression |
TIFF 6.0 Specification, Section 10 |
| CCITT T.4 |
CCITT T.4 bilevel encoding/Group 3 facsimile compression |
TIFF 6.0 Specification, Section 11 |
| CCITT T.6 |
CCITT T.6 bilevel encoding/Group 4 facsimile compression |
TIFF 6.0 Specification, Section 11 |
| LZW |
LZW compression |
TIFF 6.0 Specification, Section 13 |
| JPEG |
"New" JPEG-in-TIFF compression |
TIFF
Technical Note #2 |
| ZLib |
"Deflate/Inflate" compression (see note following this table) |
Adobe Photoshop® TIFF Technical Notes (PDF) |
| PackBits |
Byte-oriented, run length compression |
TIFF 6.0 Specification, Section 9 |
| Deflate |
"Zip-in-TIFF" compression (see note following this table) |
ZLIB Compressed Data Format Specification,
DEFLATE Compressed Data Format Specification |
| EXIF JPEG |
EXIF-specific JPEG compression (see note following this table) |
EXIF 2.2 Specification
(PDF), section 4.5.5, "Basic Structure of Thumbnail Data" |
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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