Is it possible to deliverately bring discolored tone color to image ?

[ldd2]

Greetings guys.

I have an image fan art that I have previously printed with glossy photo paper. This image was kept in a locker for about 2 years in overall 10-20° C and didn't even touch it. The fact is this print got discolored over time and now has this very interesting color looking for me... I would really appreciate to know if there's some way to bring this same or similar color looking from the physical printed image but with it's digital version through GIMP or image editor tools.


https://imgur.com/a/Soqt0yI  
(First image is the digital original version VS the other 3 that have it's current looking after being 2 years in a relatively closed up furniture and it was affected by air/ambient humidity)

I have attempted to do some testings through color image tools from GIMP v2.10 but got no luck in getting something remotely close. I may really appreciate the help. Thanks.

[tmanni]

This is not an exact workflow step by step, but the main ideas are :

- to obtain the bright regions, use Colors -> Brightness-Contrast... : in the Blending Options, set the Mode to Divide and play with the Opacity and the Contrast value
- you can also use the Screen blending mode to brighten the whole result
- the result has a strong magenta hue : use Colors -> Colorize... : choose a reddish color then in the Blending Options, set the Mode to LCH Color and play with the Opacity
- the result has low saturation : use Colors -> Saturation to decrease it
- the result has weak contrast : use Colors -> Brightness-Contrast... decrease the Contrast value
- use Filter -> Blur -> Gaussian Blur with a small value

After several attempts, you can obtain something like this:

[rich2005]

The printing process is cyan-magenta-yellow-black (CMYK) and some of these inks fade more that others.

To emulate the fade you need a CMYK filter. There are some in the Gimp plugin gmic http://www.gmic.eu

In the gmic colours section CMYK mixer with cyan removed and black (K) almost gone