Weird behavior in Gimp 2.10.14

[lonetree]

Hello all,

I'm new to this forum.

I have been a big fan for gimp and had been using gimp for many years.

I have also recently come back to linux world after "ditching" it for some reasons.

Am currently using Mac OSX and Linux Mint 19 simultaneously.  

To cut the story short, LM is installed with Gimp 2.10.14 (flatpak) and Mac with 2.10.12. I found this weird behavior when I was editing my photos with Luminosity Masking technique. I notice that on the "Light" and "Midtone" layers, all manipulation (e.g contrast, exposure etc) does not have any effect at all, only the "Dark" layers have effects. 

At first I thought it was due to my photos but when I edit the same photos with the same technique on my Mac machine with Gimp 2.10.12, everything works, so to prove that this is caused by ver 2.10.14 and not Linux Mint, I installed 2.10.14 on my Mac and the results were of the same on Linux, only the "Dark" layers works.

Has anyone face the same issues as mine?

I don't mind downgrading Gimp to 2.10.12 on my Linux machine, but I guess I have to do the manual installation approach which I might crash the entire system.

Hope someone or the developer can shed some lights? 

Thanks in advanced.

[rich2005]

This is a known problem.

see: https://www.gimp-forum.net/Thread-Saul-g...in-2-10-14

and for a more hands on method, ofnuts has a plugin see: https://www.gimp-forum.net/Thread-ofn-luminosity-masks

[lonetree]

(02-14-2020, 08:12 AM)rich2005 Wrote: This is a known problem.

see: https://www.gimp-forum.net/Thread-Saul-g...in-2-10-14

and for a more hands on method, ofnuts has a plugin see: https://www.gimp-forum.net/Thread-ofn-luminosity-masks

Thank you for replying @rich2005. So I'm not the only one with this problem.

I downloaded ofn's plugin but seems a little complicated. I'm clueless now.

[rich2005]

(02-14-2020, 12:40 PM)lonetree Wrote: I downloaded ofn's plugin but seems a little complicated. I'm clueless now.

There is a re-worked script(s) here: https://gimplearn.net/viewtopic.php?t=2576  

david_lum_mask.py and david2_lum_mask.py

[Ofnuts]

(02-14-2020, 12:40 PM)lonetree Wrote:

(02-14-2020, 08:12 AM)rich2005 Wrote: This is a known problem.

see: https://www.gimp-forum.net/Thread-Saul-g...in-2-10-14

and for a more hands on method, ofnuts has a plugin see: https://www.gimp-forum.net/Thread-ofn-luminosity-masks

Thank you for replying @rich2005. So I'm not the only one with this problem.

I downloaded ofn's plugin but seems a little complicated. I'm clueless now.

You can define your own masks, but the usual masks are in Select>Luminosity>PatDavid.

This said, while Pat's tutorial explains pretty well how luminosity masks are used, it makes people think that:

• the luminosity masks stop there, while it it only the beginning, you can/should define masks for specific ranges, depending on the pictures.
  
• all the masks can be computed at the beginning on the workflow, and this is wrong. The tutorial creates masks by adding subtracting other masks, so to get the midtones masks you have to compute everything, and you create all the masks every time.  But after your first change, the luminosity of pixels have changed, so applying masks that have been computed before the change is incorrect.
  

My script:

• lets you define arbitrary masks, that you cannot obtain by simple addition and subtraction. Past's masks are also included (they are a small subset of the possible masks)
  
• creates and applies one mask to the current content of your layer, so you can easily use successive masks that are always correct for the current contents of the layer.
  

[lonetree]

Thank you everyone.