5. Lossless JBIG Black-and-White Fax Mode
This section defines the lossless JBIG black-and-white mode or
Profile J of TIFF for facsimile. Implementations of this profile are
required to also implement Profile S.
The previous section described the extended interchange set of TIFF
fields for black-and-white fax, which provided support for the MH, MR
and MMR compression of black-and-white images. This section adds a
mode with JBIG compression capability.
5.1. Overview
This section describes a black-and-white mode that uses JBIG
compression. The ITU-T has approved the single-progression sequential
mode of JBIG [T.82] for Group 3 facsimile. JBIG coding offers
improved compression for halftoned originals. JBIG compression is
used in accordance with the application rules given in ITU-T Rec.
T.85 [T.85].
This mode is essentially the extended black-and-white mode with JBIG
compression used instead of MH, MR or MMR.
5.2. Required TIFF Fields
This section lists the required fields and the values they must have
to be ITU-compatible. Besides the fields listed in Section 2.2.1, the
extended black-and-white fax mode requires the following fields.
5.2.1. Baseline fields
The TIFF fields that SHALL be used in this mode are the same as those
described in Section 4.2.1 for the extended black-and-white mode,
with two exceptions: the following text replaces the text in Section
4.2.1 for the Compression and FillOrder fields.
Compression(259) = 9. SHORT
RequiredByTIFFBaseline
9 = ITU-T Rec. T.82 coding, applying ITU-T Rec. T.85 (JBIG). This is
a TIFF extension value.
Default = 1 (and is not applicable; field must be specified).
FillOrder(266) = 2. SHORT
RequiredByTIFFBaseline
2 = Pixels are arranged within a byte such that pixels with lower
column values are stored in the lower-order bits of the bytes, i.e.,
least significant bit first (LSB).
NOTE: The JBIG coding of black-and-white image data in Profile J
follows ITU-T Rec. T.85 [T.85], which specifies LSB first ordering
within a byte. Note that Baseline TIFF readers are only required to
support MSB first ordering or FillOrder = 1.
5.2.2. Extension fields
Same fields as those in Section 2.2.1.
5.2.3. New fields
None.
5.3. Recommended TIFF Fields
See Section 2.2.3 and 2.2.4.
5.4. Lossless JBIG Black-and-white Fax Mode Summary
Recommended fields are shown with an asterisk *.
Required fields or values are shown with a double asterisk **. If the
double asterisk is on the field name, then all the listed values are
required of implementations; if the double asterisks are in the
Values column, then only the values suffixed with a double asterisk
are required of implementations.
+---------------------------+--------------------------------+
| Baseline Fields | Values |
+---------------------------+--------------------------------+
| BitsPerSample | 1** |
+---------------------------+--------------------------------+
| Compression | 9**: JBIG coding |
+---------------------------+--------------------------------+
| DateTime* | {ASCII}: date/time in 24-hour |
| | format "YYYY:MM:DD HH:MM:SS" |
+---------------------------+--------------------------------+
| FillOrder** | 1: most significant bit first |
| | 2: least significant bit first |
+---------------------------+--------------------------------+
| ImageDescription* | {ASCII}: A string describing |
| | the contents of the image. |
+---------------------------+--------------------------------+
| ImageWidth | 1728**, 2048, 2432, 2592, |
| | 3072, 3456, 3648, 4096, 4864 |
+---------------------------+--------------------------------+
| ImageLength** | n: total number of scanlines |
| | in image |
+---------------------------+--------------------------------+
| NewSubFileType** | 2: Bit 1 identifies single |
| | page of a multi-page document |
+---------------------------+--------------------------------+
| Orientation | 1**-8, Default 1 |
+------------------------------------------------------------+
+---------------------------+--------------------------------+
| PhotometricInterpretation | 0: pixel value 1 means black |
| ** | 1: pixel value 1 means white |
+---------------------------+--------------------------------+
| ResolutionUnit** | 2: inch |
| | 3: centimeter |
+---------------------------+--------------------------------+
| RowsPerStrip** | n: number of scanlines per |
| | TIFF strip |
+---------------------------+--------------------------------+
| SamplesPerPixel** | 1 |
+---------------------------+--------------------------------+
| Software* | {ASCII}: name & release |
| | number of creator software |
+---------------------------+--------------------------------+
| StripByteCounts** | <n>: number of bytes in TIFF |
| | strip |
+---------------------------+--------------------------------+
| StripOffsets** | <n>: offset from beginning of |
| | file to each TIFF strip |
+---------------------------+--------------------------------+
| XResolution | 200, 204**, 300, 400, 408 |
| | (written in pixels/inch) |
+---------------------------+--------------------------------+
| YResolution | 98**, 196**, 100, |
| | 200, 300, 391, 400 |
| | (written in pixels/inch) |
+---------------------------+--------------------------------+
| Extension Fields |
+---------------------------+--------------------------------+
| DocumentName* | {ASCII}: name of document |
| | scanned |
+---------------------------+--------------------------------+
| PageNumber** | n,m: page number followed by |
| | total page count |
+---------------------------+--------------------------------+
| New Fields |
+---------------------------+--------------------------------+
| GlobalParametersIFD* | IFD: global parameters IFD |
+---------------------------+--------------------------------+
| ProfileType* | n: type of data stored in file |
+---------------------------+--------------------------------+
| FaxProfile* | n: ITU-compatible fax mode |
+---------------------------+--------------------------------+
| CodingMethods* | n: compression algorithms used |
| | in file |
+---------------------------+--------------------------------+