AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

2000.02.15 18:31 "Re: Help required to create a TIFF image.", by Helge Blischke

Prashant Rao wrote:
>
> Hi Helge Blischke,

> Sorry to intrude. i had sent this message yesterday to the group and > didn't the reply from anybody. I was just wondering if you could help

> me out.
>

> I have got a tiff image with the following parameters. I want to > convert this tiff image to have the IFD OFFSET at 8.

> How do I do this?
> I tried with fill order LSB2MSB and MSB2LSB. Still getting the same
> results.
>
> Thanks in Advance,
> Prashanth S.P.
>

> P.S: If I have a tiff file with first IFD offset 0x8 when I create a > new tif file using tiffcp utility, I get a new tif file with a

> different IFD offset. First IFD offset has to be 0x8 for my project.

As tiffcp lets you to change the compression method, dividing the output file into a different

number of strips or tiles, it must create the actual IFD fields last. As the StripByteCounts

and the StripOffsets fields then may gain a different number of items, their size cannot

be cumputed in advance.

You could eigher hack your own version of tiffcp or make a "tiffreorder" that only moves

the IFD to the beginning of the file, updates the offset pointers, and copies the data unchanged

behind the IFD.

But, why the hell do you need the IFD to begin at offset 8? The spec clearly states that

every TIFF reader _must_ accept an IFD sitting anywhere within the file (even weird cases with the

IFD sitting between two image strips).

Helge
>

--
H.Blischke@srz-berlin.de
H.Blischke@srz-berlin.com
H.Blischke@acm.org