JeffTucker has posted several messages in recent days regarding the correct quality settings for jpeg images ( here, here...). This led me to ask myself some questions on this subject.

I usually take my photos in raw+jpeg (medium quality), and I import the jpegs into jAlbum. Here we have a first loss of quality due to jpeg compression. But Jeff's messages made me realize that jAlbum, unless I misunderstand, also applies jpeg compression, therefore on images that have already lost a little information. In this case, wouldn't it be useful to increase the quality of jpegs above 85% in jAlbum? Does my reasoning make sense?

I am well aware that, to resize images or apply a correction, jAlbum has no other choice than to decompress the original image and do its job before re-compressing it.

However, if the image does not need special processing (image that fits the max bounds of the slides, that does not need to be cropped nor corrected, etc.), does jAlbum let it as is, without re-compression, before uploading it to the server? If so, would it be a good or bad idea to increase the image limits (e.g. 3000x3000) and import smaller images (e.g. 2000x1500).

Thanks in advance for your opinion

Not to go too far down this rabbit hole, some things to remember:

First, no camera on the planet shoots JPG's. The image is recorded in a RAW format. So, whether you take that RAW image and convert it to JPG in an app, or whether you let the camera convert it to JPG, it's still going through an initial round of compression.

Second, if the image is scaled for use on a website, which scaling is going to be better? The scaling done by the camera (if different output sizes are available), the scaling done by some other app, or the scaling done by jAlbum? Your guess is as good as mine.

Finally, if, in a double-blind test, you can't tell the difference between the results produced by various different paths, it doesn't matter, does it?

And it gets weirder. In that case, the output thumbnail image actually has been processed, even though all 3 - original, slide image, thumbnail image - have the same dimensions.

So, if I start with a 600x450 original, set thumbnail and image bounds of 1000x1000, and hold everything else constant (zero sharpening, 75% JPEG Quality, no HiDPI fiddling), I get a slide image that's absolutely identical to the original (same byte count), but a thumbnail file that's slightly smaller. But all three images are 600x450.

Go figure.

The one thing that is often overlooked is perspective correction, especially noticeable in photos of tall buildings. I guess most users are not bothered by the distortion as no one has, as far as I recall, ever asked for perspective control within jAlbum.

You are probably both right. But for my part, I have a lot of trouble with for example the facades of cathedrals or old houses when they look more like triangles than anything else. This is often the case in cities where you cannot step back to reduce the effects of perspective.

But jAlbum is a tool for creating beautiful image galleries with the most beautiful images possible