(05-04-2018, 04:25 PM)rich2005 Wrote: Ok, while you were writing that, I followed your procedure through.
A video recording: https://youtu.be/KZZJXd5pwGw 3 and a half minutes.
The thumbnail (page 2) does fail, but metadata with Gimp (any version) is still not wonderful and I suggest using some other application such as exif tool if you desperately need to save metadata.
I think the video confirms what I found. As previously mentioned I was dealing with some uncertainty regarding the difference between Page 1 & Page 2. My intuition caused me to think that the primary image was Page 2 whereas now I believe it is Page 1. More certainty was displayed in the video where Page 1 was first selected when importing the GIMP 2.10 created tif file whereas as I first selected Page 2.
While the thumbnail is not something that I particularly care about insofar as I now see how to open the real image I do think that being able to create correct tif files is extremely important. This is what I expect to be the final form for edited images that I'd like to be able to share. The reason I choose NO compression is precisely to maximize compatibility with other software (i.e., the compression algorithms are by no means universally supported). The fact that there is at least one very widely distributed viewer that cannot open a tif file created by GIMP does suggest to me that there is something wrong with at least some tif files produced (exported) by GIMP 2.10 and that this problem ought to be corrected.
I offer some speculation. My limited experience seems to isolate the problem to the situation where it only occurs when GIMP 2.10 has opened an xcf file created by a prior version of GIMP. Insofar as prior versions of GIMP make no mention of thumbnails might it be that they do NOT have support for thumbnails? If so, is it possible that this causes GIMP 2.10 to do something unintended with respect to thumbnails when processing xcf files created by prior versions of GIMP?
When it comes to metadata I have made some attempt to use ExifTool to export from an original camera developed jpg file to a tif type file created by GIMP 2.8 which basically has no metadata. This is still in the experimental stages for me but I have determined that some care is required. It is possible to screw up how other software displays images even though GIMP has no problem. For example, cameras can be held in different positions when photos are shot. It looks like orientation metadata is used to help with display of such images. Images created by GIMP tend to have intended orientation but updating this element of metadata can have very strange affects on what is displayed in some viewers that have nothing to do with orientation.
I was hoping that GIMP could recognize where the incoming values conflict with changes made during editing and get corrected in such a way that other software is at minimum able to properly display an image. The idea being that when the image we're creating with GIMP is an enhanced/refined photograph let's try to preserve relevant metadata. I've not yet experienced any problems associated with the metadata output by GIMP 2.10 but you seem to be suggesting this could easily happen. It also looks to me like even though GIMP claims to be able to edit metadata this is a somewhat selective process and doesn't apply to all of the metadata.