Old thumbnail images appearing blurry

[Joe Austin]

I recently discovered that many of my .jpg images from 12+ years ago now have blurry thumbs in the file window.   They look fine in the viewer and in PS, but are blurred in the file window.

It appears to happen with images that are jpgs generated from raw masters   (.crw, cr2 files in those days).   I have found that forcing a rescan will fix them, but finding them is a ponderous process.  The artifact appears more frequently as the images get older.

The jpgs are versions and buddies to a raw master, and a rule is set to use the jpg as image proxy for the master in the file window (as a result the master thumb appears blurred too, but rescanning the jpg fixes that).


What could be causing this and is there an easier fix than finding all of the version-jpgs from 12 +yrs ago and forcing a rescan?

[Mario]

No idea.
IMatch creates thumbnails at the time the image is indexed and stores them in the database. They are only updated when the image is modified and rescanned. IMatch loads the JPEG, resizes it to the thumbnail size configured for the database and then stores the result in the database.

If your thumbnail size was quite small (300 pixels is the default) at the time and you now display them enlarged in the File Window (there is an option that allows File Windows to scale thumbnails > 100% (Edit > Preferences > File Window) they may be blurry.

[jch2103]

Check to make sure the images haven't been set as 'protected'. (Too easily done with an accidental mouse click on the 'shield' icon in the Viewer.) If that's happened, the images will be blurred out as a privacy measure. 

[Mario]

Check to make sure the images haven't been set as 'protected'. (Too easily done with an accidental mouse click on the 'shield' icon in the Viewer.) If that's happened, the images will be blurred out as a privacy measure.

Ah, that's a very good point!
Didn't think about this. Thanks.

Use View > Protected Files visible and see if this makes a difference.

[Joe Austin]

The images are not protected and the size of the display has not changed.  Keep in mind nothing has been done with these images (I'm finding hundreds) for several years and the actual image is still good.  This does not happen in all cases but it does seem to be a majority of the cases of jpg versions from years ago.    I am finding some now that are in more recent years, but the % of cases seems to diminish with advancing years.

I

[Joe Austin]

I compared the blur caused by protection to the blur I am seeing in these cases.   The protection blur is extreme, while these images are still recognizable, just extremely soft for a thumb.

[Mario]

Then probably the thumbnail produced at the time was small.
Go to Edit > Preferences > Application and search for thumb. If the option "Allow thumbnail enlargement" is enabled, disable it. Then you see the thumbnails at their actual size in File Windows.

If they are smaller than the tiles, IMatch has to enlarge them to fit, which causes more or less severe blur.

[Joe Austin]

Thanks, that does appear to be what is happening.  Is there a way to regenerate thumbs for a jpg without doing a forced update?

[Mario]

Is there a way to regenerate thumbs for a jpg without doing a forced update?

Nope, sorry.
Write-back when needed, then force an update via Shift+Ctrl+F5.