I used Irfan View's "Auto Adjust Colors" to remove yellow tint in bathroom image under. But I want see all changes and steps so I can learn myself what variables to adjust.
If you want to "correct" images on IrfanView the only step you can do in IrfanView is Click that button and that is it. "Auto Adjust Colors" Done. Nothing else to do in the program. Nada. What is doing inside is not important, if it works it works; if it does not... but and you want to really understand:
How can I color correct the tint on my photos?
Let's focus on that.
I. My first and most important point: I use Irfanview every day, for years now, and it is one of the best image viewers among other things. Batch converting one file format to another, resampling, etc.
But it is not for correcting images. If you want to Learn how yo correct images Do NOT use Irfanview.
II. Use another program where you can actually control stuff. There are a lot of programs that can do this, from some easy to some more and more complex. The question here would be how deep you want to go.
I will focus on the simplest program I can think of, but that does not mean it is the best program to do it or even the one I use. I almost never use it, but it works. The image viewer that has a bit more options is FastStone viewer www.faststone.org.
A. The first step is to always work on a copy of your files
B. Select the folder that contains your image, click on it and go to the menu Colors Adjust Curves.
C. Play with the buttons there. Select a channel and play with the curves.
When you select another image, the viewer will ask if you want to save the changes.
One important thing you need to understand is a color wheel, some color theory. But that is too complex for one post.
Search this https://duckduckgo.com/?q=color+wheel+theory
This specific correction is called white balance, where the components of the color (RGB) on an object that is supposed to be white need to balance themselves to have the same value, therefore a neutral color White.
Another thing is brightness and contrast. Where you move the brightest target value (1) according to the graph (2) You can do this either channel by channel or the overall image, you can do it before or after the other correction.
Answering the specific question The automatic correction IrfanView makes is something like adjusting the maximum value of the three channels.
There are more professional tools for doing this.
If you really want to learn how to do it properly, use a specialized program, not a viewer. This category of programs is Raw Image processors. Some free but good options:
The difference is that you have a ton of more options, for example, you can see the three channels one above the other, or automatic tools for white balance and white point. And you do the adjustments in a nondestructive way.
Other programs can be Image editors, like Gimp, Krita, FireAlpaca, MediBang, etc. But those are another story.
I must clarify. I use Irfanview as a viewer all the time but to correct images I use a ton of the other programs, either a Raw Image processor or an Image Editor, Either paid or free ones, but mostly paid, because they have even more and more specialized options.