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From: Gerben Vos <gerben@zylab.nl>
To: "'tiff@sgi.com'" <tiff@sgi.com>
Cc: "'hans@ljungbergs.se'" <hans@ljungbergs.se>
Subject: RE: BIG TIFF file problems
Date: Mon, 5 May 1997 12:04:21 +0200
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The RowsPerStrip value is incorrectly being output as a SHORT value
instead of as a LONG, which is a problem since your image has more
than 65535 rows. It's a bug in the RIP software.

It's better to generate multiple strips, however.

Gerben Vos,
programmer, ZyLAB Europe.

>----------
>From: 	McDougle, Brian[SMTP:Brian_McDougle@cissc.canon.com]
>Sent: 	Friday 02 May 1997 18.41
>To: 	'tiff@sgi.com'
>Subject: 	RE: BIG TIFF file problems
>
>The problem is rather simple. The RowsPerStrip must be the same value as
>the ImageLength if you want 1 strip. If you divide the RowsPerStrip
>(597) into the ImageLength (66133) you get 110 with a remainder which
>equates to 111 strips. Change the RowsPerStrip and you should be fine.
>
>Brian McDougle
>Product Support Engineer, Imaging Products
>ISV Support Group
>Canon Information Systems, Inc.
>Email: bmcdougle@cissc.canon.com
>
>
>>----------
>>From: 	Hans Christiansen[SMTP:hans@ljungbergs.se]
>>Sent: 	Friday, May 02, 1997 12:04 AM
>>To: 	tiff@sgi.com
>>Subject: 	BIG TIFF file problems
>>
>>Hello
>>
>>I am having problems with very large tiff files created by our RIP software.
>>
>>The tiff file created is a bilevel tiff comprising of uncompressed data in
>>a single strip!! The size of the file is 707,953,939 bytes.
>>
>>What I want to do is compress this file using lzw, packbits or g4
>>compression.
>>
>>This is however not possible as I get the following error when trying to
>>convert using tiffcp:
>>
>>  # tiffcp -s -c lzw a1.tif a1c.tif
>>  a1.tif: Warning, incorrect count for field "StripOffsets" (1, expecting
>>  111); tag ignored.
>>
>>I have a theory as to why this is happening:
>>
>>Looking at a tiffdump of the file:
>>
>>  # tiffdump a1.tif
>>  a1.tif:
>>  Magic: 0x4d4d <big-endian> Version: 0x2a
>>  Directory 0: offset 8 (0x8) next 0 (0)
>>  SubFileType (254) LONG (4) 1<0>
>>  ImageWidth (256) LONG (4) 1<85640>
>>  ImageLength (257) LONG (4) 1<66133>
>>  BitsPerSample (258) SHORT (3) 1<1>
>>  Compression (259) SHORT (3) 1<1>
>>  Photometric (262) SHORT (3) 1<0>
>>  SamplesPerPixel (277) SHORT (3) 1<1>
>>  StripOffsets (273) LONG (4) 1<174>
>>  RowsPerStrip (278) SHORT (3) 1<597>
>>  StripByteCounts (279) LONG (4) 1<707953765>
>>  XResolution (282) RATIONAL (5) 1<2400>
>>  YResolution (283) RATIONAL (5) 1<2400>
>>
>>I noticed that the width (85640) multiplied by the height (66133)
>>(=5,663,630,120) exceeds the maximum possible value of the type uint32
>>which is 4,294,967,295. It is this 'overflow' that causes tiffcp to fail!
>>
>>I am wondering if anyone agrees with my theory.
>>
>>If so, or even if not, is there anybody who can help me solve this problem?
>>
>>Hans Christiansen
>>
>>hans@ljungbergs.se
>>
>>Ljungbergs Tryckeri AB                Tel. +46 435 120 40
>>Box 100                               Fax. +46 435 126 35
>>S-264 22 Klippan                      Mob. +46 70 518 26 49
>>Sweden
>>

