Re: TIFF Class 3 anyone?

Hans van Mourik (mailto:mourik@PYTHON.KONBIB.NL)
Fri, 17 Mar 1995 12:52:21 +0100 

Message-Id: <mailto:199503171154.FAA17363@library.wustl.edu>
Date:         Fri, 17 Mar 1995 12:52:21 +0100
From: Hans van Mourik <mailto:mourik@PYTHON.KONBIB.NL>
Subject:      Re: TIFF Class 3 anyone?
To: Multiple recipients of list IMAGELIB


Hi Dan,


By class he probably meant compression. TIFF images can be stored using
various compression schemes (This has nothing to do with the version
number TIFF 5.0 or TIFF 6.0). That's the power of TIFF! You can see what
I mean with shareware programs such as Paint Shop Pro or LView Pro 1.A
Now tag 259 indicates the compression scheme, which values might be:


  1   - uncompressed
  3   - CCITT Fax group 3 (Huffman)
  4   - CCITT Fax group 4 (Huffman), commonly used by modern Fax-machines.
  5   - Lev Zimpel Welch (LZW) compression
  6   - JPEG compression
32773 - Packbits


Here is an example that shows what the other tags of the Tagged Image
File Format may be about:


Tag name                     type        length   value (hex value)
254 NewSubfileType           4 long int     1         0 (   0 hex)
256 ImageWidth               3 short int    1       403 ( 193 hex)
257 ImageLength              3 short int    1       311 ( 137 hex)
258 BitsPerSample            3 short int    1         4 (   4 hex)
259 Compression              3 short int    1         1 (   1 hex)
262 PhotometrIntrerpr        3 short int    1         3 (   3 hex)
273 StripOffsets             4 long int    39       120 (  78 hex)
277 SamplesPerPixel          3 short int    1         1 (   1 hex)
278 RowsPerStrip             4 long int     1         8 (   8 hex)
279 StripByteCounts          4 long int    39       276 ( 114 hex)
282 XResolution              5 rational     1       300 ( 12C hex)
283 YResolution              5 rational     1       300 ( 12C hex)
296 ResolutionUnit           3 short int    1         2 (   2 hex)
320 ColorMap                 3 short int   48         8 (   8 hex)


`'''  Cheers,                    J. van Mourik
c mailto:@@                             Koninklijke Bibliotheek
   \  Hans van Mourik            National Library - the Netherlands
  -                              http://www.KonBib.nl


(Soon the virtual exposition ``A Hundred highlights from the
 Koninklijke Bibliotheek'' will be out on WWW)




On Fri, 17 Mar 1995, D.D. Barrett wrote:


> hello, i was advised the other day to use a TIFF class three to save my

> image scans on disk before I use them on a big plotter.  I checked my

> OmniPagePro 2.0 software for tiff and saw Tiff 5.0.  is that class three?

> then i went over to deskscan ii and saw something regarding Tiff but

> wasn't sure.  I would like for someone to explain this to me.

>

> Thank you -Dan

>