On Fri, Feb 12, 2021 at 10:48 AM Per Jessen wrote:

Roger Oberholtzer wrote:

...

We have had a request for 12-bit color jpeg images. Sigh

12-bit jpeg Work/openSUSE/General Roger Oberholtzer 9:59 AM (10 hours ago) We have had a request for 12-bit color jpeg images. Sigh. Anyway, isn't it the case that the jpeg library must be compiled for 12-bit instead of 8-bit support? Per Jessen via opensuse.org 10:48 AM (9 hours ago) to users Roger Oberholtzer wrote:

We have had a request for 12-bit color jpeg images. Sigh.

Anyway, isn't it the case that the jpeg library must be compiled for 12-bit instead of 8-bit support?

I would imagine that one could not then replace the system jpeg library with this version.

Has anyone tried 12-bit jpeg support in openSUSE? What was involved?

Hi Roger I know nothing about 12bit jpegs, but I was intrigued and googled it - according to the first page of hits, libjpeg and -turbo both have the support. -- Per Jessen, Zürich (-6.6°C) Per Jessen (computer.org), oS-EN Draft saving… On Fri, Feb 12, 2021 at 10:48 AM Per Jessen wrote:

Roger Oberholtzer wrote:

...

We have had a request for 12-bit color jpeg images. Sigh.

Anyway, isn't it the case that the jpeg library must be compiled for 12-bit instead of 8-bit support?

I would imagine that one could not then replace the system jpeg library with this version.

Has anyone tried 12-bit jpeg support in openSUSE? What was involved?

Hi Roger

I know nothing about 12bit jpegs, but I was intrigued and googled it - according to the first page of hits, libjpeg and -turbo both have the support.

I am trying to find out if one can access both with the same compiled library. The bit of info that we have come across implied that it required different versions of the library. I have had no chance to investigate further. It's on my list. I am also curious how one would view 12-bit red, green or blue on a PC. Perhaps the graphics cards have such support. Or they are simply set to 8-bit values. Which makes the whole exercise mysterious. Graphics files with more info that can't typically be used sounds like a solution in search of a problem. -- Roger Oberholtzer .

...

Anyway, isn't it the case that the jpeg library must be compiled for 12-bit instead of 8-bit support?

I would imagine that one could not then replace the system jpeg library with this version.

Has anyone tried 12-bit jpeg support in openSUSE? What was involved?

Hi Roger

I know nothing about 12bit jpegs, but I was intrigued and googled it - according to the first page of hits, libjpeg and -turbo both have the support.

I am trying to find out if one can access both with the same compiled library. The bit of info that we have come across implied that it required different versions of the library. I have had no chance to investigate further. It's on my list. I am also curious how one would view 12-bit red, green or blue on a PC. Perhaps the graphics cards have such support. Or they are simply set to 8-bit values. Which -- Roger Oberholtzer

On 2021-02-15 4:02 p.m., Anton Aylward wrote:

b) how I could create a 12-bit JPG.     Darktable has a 'quality' setting in its 'export' module, but I don't     think that's it.

A, found it. It's called "JPG 2000". So I tried export an old 8-bit as a 12-bit ... Well while editors such as GIMP can open it, no viewer seems able to. Suggestions? -- “Reality is so complex, we must move away from dogma, whether it’s conspiracy theories or free-market,” -- James Glattfelder. http://jth.ch/jbg

On Mon, Feb 15, 2021 at 10:03 PM Anton Aylward wrote:

On 2021-02-12 2:06 p.m., Roger Oberholtzer wrote:

...

I am also curious how one would view 12-bit red, green or blue on a PC.

And I'm curious about

(a) how I would find/identify a 12-but JPG if one exists on my system can exiftool show that up

It's not an exif thing I think. Exif is just the headers and envelope for the image.

(b) how I could create a 120bit JPG. Darktable has a 'quality' setting in its 'export' module, but I don't think that's it.

Quality is just the compression. JPEG now supports lossless compression. That would be the best quality. As to 12-bit components, I guess it depends on your software. If it is using the libjpeg that is installed system-wide, then you can probably only access up to 8 bit components. It is a compile-time thing for the library. I am not sure if it is enough to replace the libjpeg file or if you need to recompile your program as well. I suspect that you must recompile your program as well. And be sure it supports 12-bit. That is, it has no bad logic that assumes a component it 8-bits when allocating image buffer storage. I think 12-bit support was just an experimental thing for JPEG. I don't think medical images are stored that way. That's where the main push for this has come from. I thought that medical images were usually some variant on TIFF. I don't really know. -- Roger Oberholtzer