Within photographs or in film sometimes we gets a color cast effect which departs the image from being Natural. Color cast is nothing but a tint of specific color over the image making it look like as if it has been photo shooted in that mode. So to remove it we can use the following steps:
I am using the image which i have collected from this link:
Open the image in photoshop and go to the Image menu then select option adjustments to select level option. Actually we will use the separate layer for levels but for now we can use this option.
So as you can see the option opened up, here we are going to make some changes to the color picker tool (for each color point).
Lets start with the black point color picker, double click on it so that color dialog box appears. See at the right bottom portion for the number spaces for R(red), G (green), B (blue), and replace each numbers with 10. Click ok and leave.
Now double click on the white point color picker. In the color dialog box change each numbers of the RGB with 245. Click ok and leave.
And for the last grey point color picker change each numbers to 128 for each RGB channel in the color dialog box. Click ok to leave and click ok to leave the levels dialog box.
Now let me explain what we did above. On the white color picker I have set the color to white (not pure) so that if we pick any color it will brightens that particular color. For the black color point picker I have set the color to black(not pure). This will make any color dark which we pick through this tool.
For the grey point color picker I have changed the color to grey. Will add grey to the color which we pick through this tool.
Now we need to find the most highlighted color of the image where it turns to almost white. And also we need to find the most darkened portion of the image where the pixel starts to turns to black.
Alright for finding these spots lets use the threshold effect of adjustment palette.
Select the image layer and make a marked selection. Go to the Image menu to select the adjustment palette and there select the threshold option.
In the dialog box of the Threshold move the sliders full to the right untill it has reached the end. Now slowly drag the slider to the left untill you see the white spots and stop there.
Now use the color picker tool from tool panel and hold down the shift button and click on the white spot once. This is the white spot. Do not close the threshold dialog box.
Now move the sliders full to the left untill you have reached the end. Then move the slider slowly towards right untill you see the black spots to pick. Choose the spot and click on it by Color picker tool(holding down the shift button).
So now you have two spots for picking the color, cancel the threshold dialog box we are not going to use it over the image because we were using it for the white and black spot sites.
Alright, select the image layer again and this time choose the levels option from the bottom of the layers palette. See below:
We are using this option so that we could have a complete command over levels and also we could have separate layer of it.
When the palette of the levels appears, select the white point color picker and pick the color from the marked sites over the image. Now click ok and then do the same with the black point color picker. Click ok to leave the dialog box. Now select Ok button to leave the levels option.
That is it, see the difference below:
The second image shows the color cast free image with a hint of natural white color light reflection.
You can use this same principle for adding a specific color tone you can see it below.
For this please bear in mind that white and black point color picker tools color which we have chosen earlier will add to the color which you choose later.
Alright that is it for now, I hope you like this blog, thanks for reading it.