Alison Johnston

Yet another under used tool in Photoshop, but extremely useful in removing colour casts from images. Eddie Tapp calls this the 90% method, which works 100% of the time, on 90% of images. The first image below is a before and after shot, the original shot on the left, and the colour cast corrected on the right. I happen to know the colour of the top my daughter was wearing in this shot and that she doesn’t have a liver condition – well, not since the transplant …. LOL just kidding. It is also a horrible shot, with fringing going on, blown highlights etc., :-)

The next image is the original start image.

With the next image I used a levels adjustment layer, and in the dialogue box brought the sliders in to the majority of the information in each of the individuals channels. I think you will agree that it hasn’t removed the colour cast at all and has simply darkened the image.

So how can we get the image to look like the one below, with the yellow colour cast removed.

First of all open your image, or nick my original image HERE to have a practice on. You are going to have your info window open, which is located with the Histogram and Navigator window or you can just go to window>info and click on it and it will open. While we will be using a levels adjustment layer to edit this image, we will be using the numbers in the info window to make our adjustments, not the numbers in the layers palette. It sounds a little complicated at first, but once you’ve done this a couple of times you will wonder why you thought it was complicated.

You are also going to need your Colour Sampler Tool which you can find in the same bundle as the eyedropper tool and you will need to go up to the top toolbar and set the Sample Size to 5×5 Average.

So lets check what we have so far. We have an image open, we have the info window visible, we have the colour sampler tool and we have set the sample size to 5×5 average. We’re ready to start. Take a look at the image below to get an idea. The larger image that you may want to reference is HERE

You can set up to 4 points with the Colour Sampler Tool, but we are only going to be using 2 in this demonstration. You might want to reference the larger image through the link above, hold down the shift key before you click the link and it will force it to open in a new window so that you don’t have to keep flitting backwards and forwards from RB to flickr. With that image open you should be able to see where I have set the first point, simply by clicking on the image. The first point is always in relation to the white point. You can see the figures that have come up from the point that I set in Bek’s hair, they are the first numbers -

R – 214
G – 208
B – 184

Go ahead now and select the black point by clicking in one of the dark areas in the image. You can see that I have chosen the strap on the bag, and the numbers are -

R – 36
G – 42
B – 41

Click on the adjustments layer icon in the bottom of the layers palette and choose levels, the dialogue box will now appear. We will be using the individual channels within the layers dialogue box to make the adjustments, so use the drop down menu to locate them.

Because we are going to be adjusting the lights/whites we need to locate the lightest channels, in this case it is the red channel at 214, we do not need to adjust this channel but we do need to adjust the green and blue channels. From the drop down menu select the green channel and with the white slider bring it in until the reading in the info palette is 214. Do not read the numbers from the layers dialogue box, move the slider inwards until the number in the INFO window reads 214. Repeat this with the blue channel. If you can’t get it exactly to match try using your up and down arrow keys, if you still can’t get it, one higher or lower i.e. 213/215 is acceptable.

Now look at the second point you made, this is the black point, we need to look at the lowest number here rather than the highest – 0 being black. So the lowest number we have is in the red channel at 36. We need to do a similar process to what we did above, only this time we will be bringing the black slider in until the green and blue channel are at 36. Once you have done this, simply click ok on the levels dialogue box. To remove the colour sampler points from the image – with the colour sampler tool selected look in the top menu bar and you will see a ‘clear’ button, just click on this.