Solutions for files saved by Canon DPP and problems loading them into other software

[johnrmoyer]

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

[johnrmoyer]

Canon DPP saves image files with two separate size values for the ICC profile. If other software uses the smaller of the two sizes, other data might be overwritten when the ICC profile is loaded or an incomplete ICC profile might be loaded. 

A work around is to always tell DPP not to save an ICC profile and then there will not be an incorrect profile saved. An ICC profile may be added later using exiftool free software.

A correct ICC profile for sRGB may be downloaded from https://registry.color.org/rgb-registry/srgbprofiles and seems to me to work for creating JPEG files after using the sRGB color space for editing in DPP.

The ICC profile may be added to a JPG or TIF file created by DPP using exiftool.

The following command line will add the ICC profile to both a JPG and a TIF file with the same "filename" on macOS or Linux. I no longer do Windows, but expect that the quoting and wild card file name patterns will be different on Windows.

exiftool -ICC_Profile'<='../sRGB_v4_ICC_preference.icc filename.[JT][PI][FG]

I have not tried AdobeRGB ICC profiles because I do not edit in AdobeRBG.