Some image files involve a lot of time and work, so I like to keep a 16bit TIFF file of them for archiving. However, these are extremely large. While searching for alternatives, I came across the relatively new JPEG XL file format. It compresses extremely well (lossless, if you want) and, unlike JPEG, also allows storage of 16 bit (even up to 32 bit) image files. By converting my largest TIFF files into JPEG XL format, I was able to save more than 100 GB. Unfortunately, this format is still very little supported.
Is there any chance that QImage Ultimate will support JPEG XL files in the foreseeable future? At the moment I have to convert my JXL files to TIFF before printing. Support for JPEG XL would make it easier.
In addition, QImage would be another program that supports this advanced file format and would perhaps also contribute to a more rapid spread of JPEG XL.
Thank you very much!
Ernst

I fully understand your concerns.
I am currently only aware of a few programs that support JXL file format. One of them is Affinity Photo. Affinity Photo can both open and save JXL image files. Unfortunately, Photoshop can only open them using Adobe Camera Raw but not save them. Color profiles are supported - this was one of my first tests before I converted my biggest TIFF space hogs to JXL. As far as the file format itself is concerned, I can see no disadvantage compared to JPEG or TIFF. The big advantage is, that JXL compresses much better than JPEG and also saves 16bit images. Compared to a TIFF file, the size of a lossless!! compressed JXL file is less than 1/5 of the TIFF size.
Unfortunately, it seems to me that this format is being pushed aside as much as possible by influential “big players” although it has better features than png, webp, avif, heic, ... It would be high time that TIFF was finally replaced by a more modern file format with better properties.
Nevertheless, thank you very much for your quick reply. Either way, I don't want to do without Qimage any more.
Best regards,
Ernst

To tell you the truth: No, I haven't :-(
I haven't used LZW for a long time because it delays saving and often produces larger files than the uncompressed image file.
But your idea is a good one and that is why I have now carried out further investigations. I have tested different file formats using two different photos.
The first photo contains a lot of detail, which makes efficient compression more difficult.
The second photo shows a blue sky with a few clouds, which should be very easy to compress.

Here are the results:

Grainy wall with detailed wooden door    size [KB]               size [%]
                        (6176x8858px)
TIFF 16bit uncompressed                       320615                    100,00
TIFF 16bit LZW                                      416507                 129,91
TIFF 16bit ZIP                                       315873                    98,52
PNG 16bit fast                                       270140                    84,26
PNG 16bit medium                                 270135                    84,26
PNG 16bit small                                     269503                    84,06
JXL 16bit lossless                                   208481                    65,03   <<<
JXL 16bit quality 100                                24279                     7,57
JXL 8bit transcode from JPEG                    31055                     9,69
JPEG 8bit                                                37303                    11,63


Cloudy sky (9504x6336px)
TIFF 16bit uncompressed                         352901               100,00
TIFF 16bit LZW                                        399351               113,16
TIFF 16bit ZIP                                         325475                 92,23
PNG 16bit fast                                         249114                70,59
PNG 16bit medium                                   242573                68,74
PNG 16bit small                                       242539                68,73
JXL 16bit lossless                                     177324                50,25   <<<
JXL 16bit quality 100                                   3903                  1,11
JXL 8bit transcode from JPEG                       8347                  2,37
JPEG 8bit                                                  10269                 2,91

For both images, the LZW TIFF file saved with Photoshop was larger than the uncompressed TIFF file.
I got the same result when saving with Affinity Photo.
"JXL 8bit transcode from JPEG” means the following: JXL allows a lossless conversion from JPEG to JXL. That means, that the already lossy information of the JPEG will not lose more details by converting it to JPEG XL. But the resulting file is only slightly smaller than the JPEG file.
“JXL 16bit quality 100” is the storage method I tested with Affinity Photo.
Although this is not lossless, I could not detect any visual differences to the original - not even when overlaying in Photoshops layers using “Difference” at 100% view.
This extreme compression rate is still somewhat suspect to me and I would not yet trust it completely. But even the lossless compression is significantly better than with all other file formats. And as I have already checked, color profiles are also supported.
Best regards,
Ernst

This explains my bad experience with LZW. I had only ever archived 16bit TIFFs.
Thank you
Ernst