There are some pictures which color are biased.
For example, The image is too red.
In such case, we can use Curves. Curves often be used as add brightness, but Curves have a unique other way.
Add Curves on the image at first.
Click the icon which show ‘Sample in image to set white point‘. And Click the point which should be white in the image. By this action the point which should be white becomes white.
Not only the white point, There are also the black point and the grey point.
The old woman in the image wear the clothe of Black and White, I can use the Black point also.
Black becomes more Black.
Next image is also biased to blue. After adding Curves, I got more natural color image. I use her hair for the black point and her clothes white line as the white point.