Previews in Dolphin

[Qqmike]

I took photos on a cell phone.
Some of them may have come from other people who took photos on their cell phones and sent them to me.
I transferred them to my PC.
They are .jpg files (with long strange names otherwise).

--> But ... I can NOT see the previews of them (in their folders, when viewed in Dolphin).

I enabled "previews" in Dolphin, btw, and otherwise I can see previews of photos and things.

Any ideas how I can see the previews of those (cell phone) photos?

[claydoh]

All jpegs, or just those particular phone ones?
Do they open in Gwenview?

Make sure you have the package kdegraphics-thumbnailers installed, it should be.

Also, check the preview size settings to make sure there isn't a limit set, or raise the limit if there is one. Same if the files are kept on a network shared drive (I keep forgetting this one myself)

Check that the files really are jpegs, this iirc will confuse the thumbnailer if they really are png, raw, or something else.
You might check some using the file command,. I have one PNG i renamed to JPG, which did break the thumbnail:

$ file Screenshot_20220424_190715.jpg
Screenshot_20220424_190715.jpg: PNG image data, 869 x 492, 8-bit/color RGB, non-interlaced
​

Dolphin/Gwenview's file properties section just shows the file extension, not the actual file data info.

[Qqmike]

No previews in Dolphin for only those phone images -- other jpg's have a preview when viewed in Dolphin.
They do open in Gwenview -- no problem.
The size set for Local Files is "No Limit."
If I rt-click > Properties on one of those pics, the type if JPEG Image, but it also says Content is WebP image.
Also:

$ file test_for_pics/1.jpg
test_for_pics/1.jpg: RIFF (little-endian) data, Web/P image, VP8 encoding, 1024x768, Scaling: [none]x[none], YUV color, decoders should clamp

So, maybe that is the issue: WebP. A quick search indicates that you need a PPA package to preview such files (in Ubuntu, but what about using Dolphin as the file manager?).
Or, you can convert WebP to jpg (but maybe not by batches) -- and again you need to get and set up a package to do that conversion.

I have MANY such files! A few hundreds.

Having a preview of such files on my screen would help me to quickly sort/classify the pics into categories, without having to double-click > open each one to see what it is.

Thanks.

[claydoh]

So they are not jpg, and the thumbnailer doesn't like having incorrect extensions. Try renaming a file as .webp, and see if that works --- sample images I grabbed from the web preview just fine. It is the incorrect file extension causing the issue, I imagine.

Krename to the rescue? That will batch rename files, to change the extension.
Otherwise, I can't say what will make dolphin see webp images that are named as jpgs.
or why a phone app is using this format , and naming them as jpg files

webp is sort of a Google thing, but not for their camera app, or Photos service, as far as I can determine.

[Qqmike]

Try renaming a file as .webp, and see if that works --- sample images I grabbed from the web preview just fine. It is the incorrect file extension causing the issue, I imagine.

That worked!

webp is sort of a Google thing, but not for their camera app, or Photos service, as far as I can determine.

Well, that's what I was thinking, too. Maybe these photos somehow came off a website, like Facebook or some messenger service, IMO?, or some-such.

I COULD look into changing those files from jpg to webp ... (actually converting them, not just naming).

[claydoh]

I COULD look into changing those files from jpg to webp ... (actually converting them, not just naming

They already are webp, so I assume you mean the other way 'round?
That might be helpful for editing purposes, I think., depending on the application used.

[Qqmike]

Yes, convert those webp files to jpg.

[Qqmike]

Krename works to simply rename the files with a (custom) extension of .webp.

[Qqmike]

Krename is now an option in my context menu when using Dolphin (right-click > rename with Krename). Pretty cool. You can highlight all files in a folder and immediately rename the batch of them right there, without doing any special navigation. Thanks!