In case one sees problems loading TIF files or JPG files saved by Canon DPP software, here are explanations.
The most recent update to Gimp free software on Debian Linux can once again open TIFF files saved by Canon DPP. Imagemagick still cannot. The previous version of Gimp failed to load them due to a security update.
If you see problems loading TIFF files saved by Canon DPP, there are two problems in those TIFF files. The default value is according to the TIFF standard and should not cause a problem. The second problem is an incorrect size for an embedded ICC profile. The latest Gimp ignores the ICC problem and offers to convert to a Gimp ICC and then saves a correct ICC when exporting the file.
When Graphicsmagick tries to load either a JPG or a TIF file saved from Canon DPP and convert to a PNG it fails with this error message: "convert: Incorrect data in iCCP `IMG_5482c.png' @ error/png.c/MagickPNGErrorHandler/1491." The behavior of Gimp is friendlier since it just fixes the problem.
The problem in TIF files was a crufty ancient default value in the TIFF standard and the difficulty that created in calculating the amount of memory to allocate for a TIFF image when loading it.
The TIFF standard is at: https://web.archive.org/web/20180810205359/https://www.adobe.io/content/udp/en/open/standards/TIFF/_... and page 39 mentions the default value in an example of how to calculate size. Canon DPP still uses that default value, "effectively infinity", and confuses some modern software.
I hope this might explain odd behavior that some might see.
John
