TIFF and LibTiff Mail List Archive


1998.12.01 17:17 "MH coding", by A. Grisard
1998.12.01 21:40 "Re: MH coding", by Frank D. Cringle
1998.12.02 15:41 "MH Coding "on the wire"", by A. Grisard

1998.12.02 15:41 "MH Coding "on the wire"", by A. Grisard

EOL is 11 (or more) zeros followed by a 1. End of page (strictly speaking: return to control) is 6 consecutive EOLs and is only necessary "on the wire", not when compressed data are encapsulated in a tiff file.

I understand that "on the wire" means "over the serial line" to an an external fax modem for example. What I need to know is the format of the fax data that actually flows *over the transmission line* to the DCE.

Following Frank's recommendation, I managed to get a copy of Section 10 of the TIFF 6.0 Specification. That helps for a beginning. Thanks to Frank. But there are still some questions...

The specs state on page 44: 'No EOL code words are used'. Is this valid for stored data, line data or both?

In general, I understand that one fax line "on the wire" is composed of as many black and white run length codes as necessary to describe a total of 1.728 pixels (for normal resolution). The resulting bit stream is then split into 8-bit bytes, the last byte being filled with zeroes, if incomplete. Every single line is then terminated by an EOL code of 11 or more zeroes followed by a 1.

Is this correct?

Is it really necessary to staff the last (incomplete) byte of a line even if EOL code is present?

A. Grisard