[magick-users] Problem converting large tiff pictures

[Ross Presser]

On Tue, Oct 7, 2008 at 12:30 AM, Anthony Thyssen <anthony at griffith.edu.au>wrote:

> <duc.sequere.aut.de.via.decede at imagemagick.org>
>
>  3/ The "thumbnail" program probably does not generate good thumbnails
>     but horible 'smalpled' thumbnails.  IM produces a "quality" result.
>

After some research, and some puzzling banging of my head on the table
trying to figure out why I kept getting 8 byte empty TIFFs, it appears that
thumbnail only works on 1 bit per pixel TIFFs. It is intended for fax
images.

       *thumbnail* is a program written to show how one might use the SubIFD tag
       (#330) to store thumbnail images.  *thumbnail* copies a TIFF Class F fac-
       simile  file  to  the output file and for each image an 8-bit greyscale
       *thumbnail* *sketch*.  The output file contains the  thumbnail
image  with
       the associated full-resolution page linked below with the SubIFD tag.

       By  default,  thumbnail  images are 216 pixels wide by 274 pixels high.
       Pixels are calculated by sampling and filtering the  input  image  with
       each pixel value passed through a contrast curve.

Worse yet, it seems to have some trouble with decompressing; the results I
get have white vertical stripes. This is discussed a bit in various google
results but I don't really understand.