How to reduce the red color on image ?

[david]

The image at the start of this thread has dimensions of 734 pixels high and 563 pixels wide.
In GIMP duplicate the original layer.
With this layer active go to Filters/Blur/Pixelise and set Block width and Block height to 734 pixels (the maximum dimension of the image) - this converts the image to a single large pixel of the average colour of the picture.

   

Then use Colours/Invert to change the layer to its complementary colour and change its mode to overlay.

   

You have three alternative methods of achieving your required result. Please read carefully the posts by Pixlab, denzjos and myself and perhaps write yourself notes of the steps in each case to make sure you understand what you will be doing.

[denzjos]

@Stephen Liu, G'Mic-Qt only solution for this kind of problem. All kind of problems, all kind of solutions.?
   

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A other solution is by using this plugin : https://sourceforge.net/projects/johnlakgimp/

After install, find it in the gimp menu : Colors / Color Grading 
   

[Stephen Liu]

       

(07-20-2022, 07:32 AM)david Wrote: The image at the start of this thread has dimensions of 734 pixels high and 563 pixels wide.
In GIMP duplicate the original layer.
With this layer active go to Filters/Blur/Pixelise and set Block width and Block height to 734 pixels (the maximum dimension of the image) - this converts the image to a single large pixel of the average colour of the picture.



Then use Colours/Invert to change the layer to its complementary colour and change its mode to overlay.



You have three alternative methods of achieving your required result. Please read carefully the posts by Pixlab, denzjos and myself and perhaps write yourself notes of the steps in each case to make sure you understand what you will be doing.

Thanks for your advice.

I suspect whether there is something wrong on my GIMP 2.10.32 here.  Following the steps advised by folks previously here I couldn't produce same result.

Performed following steps as advised by you;
Filters -> Blur -> Pixelize

pls refer to attached screenshot_pixelize_1.png

then -> OK

Colors -> Invert

Pls refer to screenshot_invert.png

I couldn't find the file "photo-sample.jpg copy"

Regards

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(07-20-2022, 08:23 AM)denzjos Wrote: @Stephen Liu, G'Mic-Qt only solution for this kind of problem. All kind of problems, all kind of solutions.?

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A other solution is by using this plugin : https://sourceforge.net/projects/johnlakgimp/

After install, find it in the gimp menu : Colors / Color Grading 

Thanks for your advice.

I have the plugin "color_grading_v174.tar.xz" download on Ubuntu 20.40 desktop

Whether performing following steps the plugin will be automatically added to my GIMP 2.10.32 ?

On Ubuntu Terminal run;

Code:

$ tar -xf color_grading_v174.tar.xz
$ cd color_grading_v174
$ ./configure
$ make
$ sudo make install

Pls advise.  Thanks

Regards

[denzjos]

@Stephen Liu, with NIK Color Efex 4 filter as a Shellout in gimp you get an acceptable result. More possibilities with this program. For installation see : https://www.gimp-forum.net/Thread-PS-NIK...t=Shellout

   

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@Stephen Liu, another solution is adjusting the red, green and blue channels in gimp levels (more info : https://www.youtube.com/watch?v=3iehOYBYgXE)
   

[PixLab]

(07-20-2022, 06:18 AM)Stephen Liu Wrote: "Set foreground color" already selected.

Clinking the "Color Picker" starts "Change Foreground Color" screen.  Pls refer to screenshot

Regards

Why makes it simple when you can make it harder?
Did I tell you to click on the "Change Foreground Color"? No... Although you could do it from there as well, but no more for me today, PixLab is closing.
BTW, seeing all your screenshot, your GIMP is very fine and behaves as it should, the problem is between monitor and chair, though.

@denzjos and @david over to you guys, I gave up.

[sallyanne]

For that photo and any others like it I would go to Colors > Levels> Auto input levels (Not Auto white balance)
Otherwise if you want to make it just how you would like it. Go to levels and pull the red to the right. You may want to move all your center sliders in levels just a small amount.

Value to the left - right make a picture lighter - darker
Red to the left - right will give you more red - green
Blue to the left - right will give you more blue - yellow
Green to the left - right will give you more green - magenta

Sometimes a 'little' extra contrast helps. But not if the photo is already dark.
[attachment=8392]
[attachment=8393]
[attachment=8394]

[Stephen Liu]

(07-24-2022, 06:54 AM)sallyanne Wrote: - snip -

Value to the left - right make a picture lighter - darker
Red to the left - right will give you more red - green
Blue to the left - right will give you more blue - yellow
Green to the left - right will give you more green - magenta

Moving the center handle (small triangle icon)
Pls advise "Input Level" or "Output Level" ?

Thanks

Regards

[sallyanne]

What you could do is the auto input levels first and then if it seems there is still some discrepency in the colour in the 'adjust colour Levels Window' you will see two bars. Using the top bar, move the centre arrow to suit your taste. You may have to do it for each color and you may have to do it differently for each photo so I cannot give you input/output as each photo may be different.

[Stephen Liu]

   

(07-25-2022, 01:46 AM)sallyanne Wrote: What you could do is the auto input levels first and then if it seems there is still some discrepency in the colour in the 'adjust colour Levels Window' you will see two bars. Using the top bar, move the centre arrow to suit your taste. You may have to do it for each color and you may have to do it differently for each photo so I cannot give you input/output as each photo may be different.

Hi sallyanne,

Thanks for your advice.

After testing for several days I think the best approach to restore faded photos tinted with yellowish color is;

Colors -> Colors Balance
pls refer to screenshot upload

It is time consuming not only with 2/3 clicks.

But I still can't understand their features:_
Shadows/Midtones/Highlights

Preserve luminsity/Blending Options

Mode/Opacity

Can you help?

Can any folk on the forum shed me some light?  Thanks

Regards

[denzjos]

Some information : https://www.color-meanings.com/color-balance/