Discard JPG color profiles - interpret them as simple RGB

[Abrimaal]

Once there was only RGB, CMYK and grayscale and nobody took care about color spaces and profiles. What happened that today we have so many color profiles, and they apply only to .jpg format?
I process photos in various editors, each of them saves .jpg with a color profile. Some editors, especially mobile apps even don't inform the user that they change the original profile and apply another.

I often stitch together the same image processed in various editors, because the sky looks great in one version.

In another version of the same photo the shadows look the best, in another there is a detail that I want to expose.

Using include / exclude masks, Hugin blends the images and creates a perfect photo from all the versions.

Even without finding control points. I just reset positions and stitch - they are the same size.

Often the creation of a perfect photo or a collage ends while opening the images.
If at least one of images uses a different color profile, it cannot be loaded, even by force (by changing filename in .pto file).
I don't know any profile converter, so I save all photos to .png or .tif. The color profiles are discarded, Hugin opens them all and the difference is almost invisible.

Can I ask for enabling such dialog while opening: Discard the color profiles?
Or such a checkbox in settings
[ v ] Discard .jpg color profiles if they are different.

[Bruno Postle]

I open them all in GIMP and convert to sRGB, but this isn't something we can expect all users to find obvious.

Possible solutions are:
1. Transparently convert everything to a single profile when remapping.
2. Discard profiles for all images but the 'anchor', and let the Hugin photometric optimiser sort out the rest.

I have no idea how hard 1 is, and 2 would need some testing to see how viable it is.

--
Bruno

[Abrimaal]

Ad GIMP and other external converters: time counts. Often we have to prepare a photo document to publish it the same day, and we want to have good photos for future projects.

One more possible solution. Hugin work files are in .tif format.

While opening (with the option discard color profiles selected), all .jpg images are saved temporarily as .tif.

The panorama is stitched from these .tif files. Original .jpg files are not used. 

[David W. Jones]

Unlike the original poster, my images don't become JPG until the final production panorama is converted from 48-bit TIFF using RawTherapee or LuminanceHDR. I shoot raw format in the camera, so there's no JPG at all during processing.

--
David W. Jones
gnome...@gmail.com
wandering the landscape of god
http://dancingtreefrog.com

Sent from my Android device with F/LOSS K-9 Mail.

[David W. Jones]

On 3/19/20 9:07 PM, Bruno Postle wrote:
> I open them all in GIMP and convert to sRGB, but this isn't something
> we can expect all users to find obvious.
>
> Possible solutions are:
> 1. Transparently convert everything to a
> single profile when remapping.
>
> 2. Discard profiles for all images but
> the 'anchor', and let the Hugin photometric optimiser sort out the
> rest.
>
> I have no idea how hard 1 is, and 2 would need some testing to see
> how viable it is.

Problem with #2 is - what happens if you change the anchor image? Or
would discarding the profile only happen when the photometric optimizer
runs? If so, that would make it difficult to change the anchor image and
rerun the optimizer. I find myself doing that when using one anchor
makes exposure/etc blow up too much in other frames. Then I change the
anchor and re-optimize until I get exposures I like.

I think I like #1 better. But I don't use JPG in processing, so I'm not
the best person to talk about this.

[Jan Dubiec]

On 2020-03-21 01:03, David W. Jones wrote:
> Unlike the original poster, my images don't become JPG until the
> final production panorama is converted from 48-bit TIFF using
> RawTherapee or LuminanceHDR. I shoot raw format in the camera, so

> there's no JPG at all during processing.Could you explain your workflow a bit more? What is between RAW and
Hugin? RawTherapee I suppose, but what "profile" do you use? And what
exactly TIFF->JPEG "converter" does? Does it do e.g. tone mapping?

[Gunter Königsmann]

Are wie sure that the color profiles are never an important part of the jpeg that will make them more producible if it is missing? If not removing them might be no option, bit applying them on uncompressing the image will. I believe no camera will use something like the profiles found in http://www.color.org/version4html.xalter that excjange redwith green or similaf but one never knows.
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

[Bruno Postle]

This is not just a problem with JPEG files, most image formats can carry colour profiles. It just happens that your TIFF process results in all photos having the same, or no, profile.

--
Bruno

[David W. Jones]

Tonemapping. My RAW and TIFF images are 16-bit per color (RGB). JPG has
only 8-bits per color. Every time you convert from 16-bit to 8-bit, you
lose color information. That's why, for instance, you can adjust
exposure on 48-bit TIFFs but not in JPGs.

Anyway, I think the original poster's question boiled down to "Why have
color profiles at all?" I found this on howtogeek, maybe it's helpful:

https://www.howtogeek.com/343900/what-is-a-color-profile/

--
David W. Jones
gnome...@gmail.com
wandering the landscape of god
http://dancingtreefrog.com

My password is the last 8 digits of π.