I don't see any difference

That's good, because they're actually the same image. I manually cropped the slide image to the theme image dimensions, then swapped it out in the finished album. Just a quick sanity test, to make sure we weren't suffering from an optical illusion, or confirmation bias. Always worth a quick check.

To sum up my testing:

Three albums, all with sharpening 50%, JPEG Quality 85%, smooth/standard scaling.

2500x1471 original, image bounds 1920x1920 (just to make sure no extra cropping gets done), normal jAlbum processing: (demo album removed)

2500x1471 original, image bounds 1920x1920, manually replaced the generated theme image: (demo album removed)

2500x691 original, pre-cropped to the same aspect ratio as the theme image (6.4:1), image bounds 1920x300, normal jAlbum processing: (demo album removed)

In each case, the theme image is fine. This tells me that the jAlbum core is behaving properly, and doing the best job it can with the source material.

What Tiger is doing, I can't say. It's doing the image generation on its own, but that's all internal, in code I can't see. It's calling the same routines from the jAlbum core as Neptune, but in a different way. That shouldn't matter, but you're seeing a difference. I don't really know how to test it, so I'll have to leave it to Laza, if he wants to investigate further.

(BTW, if you have larger "true" originals, use them. Scaling them in some other app, then letting jAlbum scale them again raises the possibility of some degradation. One scaling operation is always better than two or three.)

Edited by: JeffTucker on 18 Dec 2024, 20:18 - demo albums removed, having served their purpose

The "original quality" can never be reached because the JPG uses lossy compression, which means it will lose some detail during the saving process.

I made a test album to compare normal images and the hero image. If they are the same size, they are identical. This proves that Tiger and jAlbum are applying the exact same settings for both.
https://laza.jalbum.net/Testing%20folder%20image%20quality/index.html

Naturally, if the slide image is larger, it has more details, and when they are smaller than the 1:1 size, a high DPI monitor can display more details.

Laza, the cover photo looks satisfactory on your test album. What settings did you use for this on JAlbum and Tiger?

Edited by: BJWH on 18 Dec 2024, 14:07

Choose File > Import > Settings from Published Album, and paste the URL.

A moment of idle speculation....

One of the reasons I have always railed against variants is that they're designed to cure a ten-year-old problem, to wit, slow connections and limited bandwidth on some devices. So, variants try to "right size" the slide image that's fed to the visitor. I maintain that the need for this is gone. Just choose image bounds large enough to provide a good show on the typical large monitor, and don't worry about the bandwidth.

Maybe we're evolving towards a stage at which we don't need scaled images at all. Just use the original every time. Have jAlbum produce thumbnails (because a page of 100 originals would still be staggeringly slow to load), and apply image edits, if any, but not make scaled slides.

Just did a quick check, and of all the Laza skins, only Tiger is making this mistake.