2005.06.07 19:15 "Re: [Tiff] Group4 compression & alpha channel", by Andrey Kiselev

Hi, Bob,

It has been observed that when GraphicsMagick writes a min-is-black TIFF image with Group4 compression and an alpha channel (as an extra sample) that the right half of the image is lost. The image description is:

I strongly suspect that this loss of data is due to libtiff but have not done a thorough investigation yet to make absolutely sure. The same occurs when using FAX compression.

By simply not requesting Group4 or FAX compression, the file is saved and read ok. This works:

Are there any known issues in libtiff with this scenario?

I do not remember any reports of such a bug. I think it is a matter for our Bugzilla.

Regards,
Andrey

Andrey V. Kiselev
Home phone: +7 812 5970603 ICQ# 26871517