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Topic: Ristretto (XFCE image viewer) displaying photos badly - noise, jagged diagonals (Read 773 times) previous topic - next topic
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Ristretto (XFCE image viewer) displaying photos badly - noise, jagged diagonals

I am using Mate desktop, but usually use Ristretto to view photos because Eye of Mate displays image thumbnails on the bottom not the side which doesn't work well on a wide screen display as most photos are narrower than wide screen.
On high resolution photos like 10 or 16MP showing the whole photo (zoom to fit window) in Ristretto, the XFCE image viewer, results in noisy images with jagged diagonal lines. Eye of Mate is much better. This is true on both my Dell M4500 and E7470, Nvidia and Intel graphics respectively. On the M4500 which is a bit slower to load pictures, having an SSD rather than NVME drive, you can see that Eye of Mate initially comes up with the same noisy picture that you see in Ristretto, but then it redraws it in better quality. This redraw never happens in Ristretto and you are left with the trashy quality preview, and although you can zoom in to see the real quality of the image, you can't view the whole picture properly. It's possible to see this transition happen on the E7470 in EOM but it's only briefly on screen.

Edit:
Quick image viewer tests, which might be helpful for anyone who finds the same problem, I tried:
 viewnior pqiv gthumb loupe gpicview feh ephoto pix sxiv imv xviewer lximage-qt gwenview
(It's possible I could have missed some config to make some of these do more what I wanted, but there was nothing obvious)
Very basic - feh, pqiv, sxiv, imv - imv has same low quality image as ristretto
No thumbnail side or bottom bar - image viewer (aka loupe), viewnior and lximage-qt, gpicview, ephoto
EOM style thumbnails on bottom only - gwenview (has many KDE related deps), xviewer
Better alternatives - gthumb, pix - which is gthumb without white border on picture when maximised but not fullscreen, but thumbnail sidebar doesn't appear on startup, seems to have some kind of issues around that, pix-git was the same.
 + zoom button wasn't working in either gthumb or pix -  I needed to set manually in hamburger 3 line icon - preferences - shortcuts - scroll down to Zoom In, click on it, press = key. I imagine it was set to a literal + symbol like you would get on a numerical keypad and = or shift = for + was not registered as +. Also unlike Ristretto, Page Up and Page Down are next / previous picture, with the arrow keys used to scroll around zoomed images. So Gthumb seems to be the best Ristretto replacement to use for now that I found in the repos and I'll run with that unless it reveals some problem behaviour I've not yet encountered.

Re: Ristretto (XFCE image viewer) displaying photos badly - noise, jagged diagonals

Reply #1 –
Does ristretto have a setting to select zoom algorithm? For example, my image viewer of choice can do nearest or bilinear.

Re: Ristretto (XFCE image viewer) displaying photos badly - noise, jagged diagonals

Reply #2 –
In the Ristretto settings I can tick:
Limit rendering quality
Enable smoothing
both of which improve the image, but the result is still not as good as the reloaded eom / gthumb. I would guess it's working on a compromised initial image. I think it's something like the progressive jpeg idea. Possibly though, this is something done in Mate which Ristretto, being from XFCE, is not adapted for, I haven't tried Ristretto using a complete XFCE desktop to test it there.

Re: Ristretto (XFCE image viewer) displaying photos badly - noise, jagged diagonals

Reply #3 –
No, switching to XFCE4 desktop made no difference, I tried both Ristretto and Gthumb with the same results. Perhaps it is just something related to the way Ristretto rescales images to the screen size, and what kind of antialiasing etc. it applies, because looking even at Gthumb and EOM critically, although they are better than Ristretto on it's best settings, I can still see some artifacts like diagonal lines on closely spaced parallel lines which disappear when zoomed in far enough to reveal the true detail. Anyway, Gthumb also adds some handy extra editing features over Ristretto so it was worthwhile giving it a go to discover what it could do, as I hadn't tried it, or certainly not much and not recently if I did.  :D

Edit - I tried geeqie, and it does display the images themselves nicely, but doesn't seem to have any thumbnail bar at all. Usually I take a bunch of photos then flip through them deleting the worst ones, and it's helpful to have the thumbnails in view to make sure I'm left with one of each scene. It's often the case there will be small details which make one look better even though all were basically OK. On my laptops if the thumbnails are at the bottom it makes the main image quite a bit smaller than when they are on the side, but with a bigger monitor or different use  case then another viewer could be more suitable of course.

Re: Ristretto (XFCE image viewer) displaying photos badly - noise, jagged diagonals

Reply #4 –
I'm a bit off topic.

I've always liked simple, lightweight, practical, and fast viewers.

Currently, on XFCE, I use GPicView and Viewnior.