Bad quality thumbnails in Dolphin

I am an avid media collector and many of my images have bad blurry or jaggy thumbnails, while most of them are fine. Any way to fix this?
It won’t let me post images here.

You can make a screenshot and then link it to an imgur upload.

Just post the link like this: imgur(dot)com(slash)123456

It says “An error occurred: Sorry, you can’t include links in your posts.”, I think it’s because this account is new.

Even with this format? :point_down:

Oh I see. Here’s an example:
The top right thumbnail is very blurry even at max thumbnail size. Here’s the image if you want to test.

The thumbnail is notably sharper for me.

Click to view at original size.

What is the md5 hash of the image before you uploaded it to imgur?

md5sum "Intelligent Warming.jpg"

Ok it seems imgur re-encodes the image. Here’s a site that doesn’t, I tested and it’s the same hash.

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Just as I suspected, and it’s also something I wanted to make sure of before continuing.


What you’re seeing is the backend thumbnailer using the embedded EXIF thumbnail. It’s not “generating” a thumbnail, but rather saving CPU cycles by simply reading and using the JPEG metadata and finding an already-existing embedded thumbnail.

You could use exiv2 to remove the embedded EXIF thumbnails without modifying nor re-compressing the JPEGs. (Keep in mind you’ll have to clear your thumbnail cache for the thumbnailer to create newly generated thumbnails.)

exiv2 -d t file.jpg

This can also use a wildcard, to work on all files within a folder, or even in a script/loop/find to be used recursively. Just be warned: It’s a one-way operation, and it will affect the images in-place.

For example, to do all JPEGs in the current directory:

exiv2 -d t *.{jpg,jpeg}

I must repeat. BE CAREFUL when using one-way operations.

Ahh jpegs and their quirks, weird because I don’t remember this happening last time I used Manjaro, which was a few months ago.
I have everything backed up, will try that command line utility.
Thanks a lot.

I believe under Dolphin’s preferences → Previews, there used to be an explicit option next to the JPEG thumbnailer to use (or to not use) embedded EXIF thumbnails. I think the developers removed that option. :frowning:

EDIT: Looks like I remembered correctly!

Again, I’m disappointed in the direction KDE’s developers are heading… :pensive:

In my opinion, they should have left it up to each user whether or not they want the thumbnailer to generate thumbnails from the JPEG image itself, or to use an embedded EXIF thumbnail if one exists.

Now that they’ve removed that option, you’re stuck with these quirks that decrease the user-experience quality.

Way to go, KDE…

They really want to be more like GNOME. “Fewer options means less clutter! Less ‘confusion!’ Which means a better user experience! At least according to our studies.” :woozy_face:

Yup, it is a shame. I tried the command and it clears them right up, at least. Nice.

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And now you also learned that imgur modifies the uploaded file, so it’s terrible for archiving or sharing an image exactly as it is. :wink:

Problem is, imgur is a well-known service, just like “Google”. :person_shrugging:

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