PdfCCITTFaxDecodeFilter Class

A flag indicating whether 1 bits shall be interpreted as black pixels and 0 bits as white pixels, the reverse of the normal PDF convention for image data.

Default value: .

The width of the image in pixels. If the value is not a multiple of 8, the filter shall adjust the width of the unencoded image to the next multiple of 8 so that each line starts on a byte boundary.

Default value: 1728.

The number of damaged rows of data that shall be tolerated before an error occurs. This entry shall apply only if EndOfLine is and K is non-negative. Tolerating a damaged row shall mean locating its end in the encoded data by searching for an EndOfLine pattern and then substituting decoded data from the previous row if the previous row was not damaged, or a white scan line if the previous row was also damaged.

Default value: 0.

A flag indicating whether the filter shall expect extra 0 bits before each encoded line so that the line begins on a byte boundary. If , the filter shall skip over encoded bits to begin decoding each line at a byte boundary. If , the filter shall not expect extra bits in the encoded representation.

Default value: .

A flag indicating whether the filter shall expect the encoded data to be terminated by an end-of-block pattern, overriding the Rows parameter. If , the filter shall stop when it has decoded the number of lines indicated by Rows or when its data has been exhausted, whichever occurs first. The end-of-block pattern shall be the CCITT end-of-facsimile-block (EOFB) or return-to-control (RTC) appropriate for the K parameter.

Default value: .

A flag indicating whether end-of-line bit patterns shall be present in the encoding. The PdfCCITTFaxDecodeFilter shall always accept end-of-line bit patterns. If EndOfLine is end-of-line bit patterns shall be present.

Default value: .

A code identifying the encoding scheme used:

<0

Pure two-dimensional encoding (Group 4)

=0

Pure one-dimensional encoding (Group 3, 1-D)

>0

Mixed one- and two-dimensional encoding (Group 3, 2-D), in which a line encoded one-dimensionally may be followed by at most K − 1 lines encoded two-dimensionally

The filter shall distinguish among negative, zero, and positive values of K to determine how to interpret the encoded data; however, it shall not distinguish between different positive K values.

Default value: 0.

The height of the image in scan lines. If the value is 0, the image’s height is not predetermined, and the encoded data shall be terminated by an end-of-block bit pattern or by the end of the filter’s data.

Default value: 0.