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Lesson 7: Photoshop Colour Correction Techniques
We're now ready to start looking at the most important colour correction techniques in Photoshop. Colour correction is about making the colour in your photos match what you saw with your eye. But it can also be used to play with colours to create a certain effect that you like the look of.
We begin the process of creating the right colour balance in a photo by choosing a white balance when taking a picture. If you shoot in Raw, the white balance (another way of saying colour balance) is set in post-production, which we'll be looking at in this tutorial. So let's get going...
First, open your picture in the right colour space
An important first step before following the rest of this tutorial is to make sure that you open your photo in Photoshop in the same colour mode that you shot it in. Otherwise the colours will not display accurately. In your camera menu, you can choose between sRGB, Adobe RGB (1998) and ProPhoto RGB modes.
Open your image in Photoshop and go to Edit>Color Settings and choose the right RGB colour mode from the list under "Working Spaces". Under "Color Management Policies" select "Preserve Embedded Profiles", so that Photoshop will always open images in the RGB mode they were taken in. Then you don't have to worry about checking.
If you're uncertain about what colour modes are, re-visit lesson 2 of this series: Why Colour Modes and Bit Depth Matter.
Automatic vs manual colour correction
Photoshop allows us to make either automatic or manual color corrections. This is the case both within the Photoshop workspace, and using the Camera Raw converter. In this tutorial I'll explain to you how to do both.
Automatic adjustments involve clever tools that make instantaneous adjustments. Manual adjustments involve fine tuning things ourselves. You can actually use a combination of the 2, but let's start by looking at automatic corrections...
Automatic colour correction
Colour correction in Photoshop is best done using a Curves adjustment layer (which we introduced in lesson 6: Having Fun With Ajustment Layers). So open an image and create a Curves adjustment layer.
Start image, with incorrect colour balance:
Select the gray (middle) pipette tool from the left of the Curves box, and find a point in your photo that you know is supposed to look gray. Click on it once, and the entire image will fall into line. Done!
If you're struggling to find a gray point, use the black or white pipette tools with a black or white point in the photo, which can sometimes be easier to locate.
Final image, colour-corrected with 1 click:
Manual colour correction
With the above automatic correction, Photoshop is changing the individual red, green and blue colour channels without us having to do anything. But we can do that ourselves if we wish to.
So, create a Curves adjustment layer and, instead of using the pipette tool, this time select Red from the drop down menu at the top. Place a marker in the centre of the graph and drag it up or down, to increase/decrease the reds in the image. Do the same with the Blues and the Greens.
Make changes to the colour channels based on your own 'eye'. It's normally quite easy to see whether a photo needs a bit more red, or a little less blue to become more accurate.
Something I sometimes do is to use the gray pipette tool as a starting point, which gets it nearly right, and then fine tune the channels a little bit by hand.
You can select RGB to view all the channles that you have adjusted when you're finished:
Colour correction in Camera Raw
I shoot in Raw almost all the time. It gives you more colour information to play with when editing and the finished results are always better.
Open a Raw file to bring up the Camera Raw dialogue box. The 3rd tool from the left at the top is the White Balance Tool. Use this in the same way as the gray pipette in Curves. Click on a gray point to colour correct the photo.
You also have the choice of selecting a pre-set white balance option from the list at the top of the Basic Tab (i.e. Daylight, Tungsten etc.).
So those are the automatic correction options. But we can specify a Custom white balance (manual correction) by using the Temperature and Tint sliders towards the top of the Basic Tab. Move Temperature slider to change the balance of blue/yellow and the tint slider to change the balance of green/magenta.
Colour correction for skin tone
When correcting the colour of skin tone it's good to be a little bit more precise. Luckily, there's a really easy system for doing this in Photoshop. So, open up a portrait photo and follow these steps...
Start image, with incorrect skin tone:
Firstly, open up the eye-dropper tool from the toolbar (5th tool down). In the options at the top, make sure "Point Sample" is not selected (this works with only 1 pixel!). Instead, choose 5x5 Average.
Hold Shift and click on an area of skin that contains clear colour information. The Information panel will appear, showing the balance of RGB colours in that area. Click on the pipette tool next to the bottom list of RGB colours, and choose CMYK Color from the menu.
Now open a Curves layer. We're going to adjust the balance of CMYK colours shown, by changing the individual RGB colour channels. The weight of each CMYK colour is shown next to it in the Information panel, with a percentage. Can you see that?
For typical skin tone on a person of Caucasian ethnicity, yellow and magenta should be about the same level, with a little bit more yellow. Meanwhile cyan should be between 1/3 nd 1/5 of the yellow/magenta level. So we can times the cyan percentage by 3, 4 or 5 to work out if it is in the right ballpark. There should be no black ('k'). These amounts are just a guideline, but they're really handy. In this example picture, you'll see that the balance of colours is way off!
So, select the red channel to adjust the cyan, the green for the magenta and the blue for the yellow (in other words, R, G, B and C, M, Y are in the same order, helpfully). You'll need to adjust one channel more than once because they all change a little bit with each adjustment. Here are the numbers that worked for my example picture, which fit the guide perefectly:
That's it - corrected skin tone. I often find that this balance of slightly more yellow than magenta, plus 1/3 to 1/5 of cyan works perfectly. It's actually very tricky to recognize just how 'off' colours are until you change them sometimes.
Final colour-corrected skin:
The colour balance obviously differs for people with paler/darker skin, and of different ethnicities. You'll find that the following levels of CMYK are in the right ballpark for people of African ethnicity: Cyan - 45 / Yellow - 75 / Black - 50. For people of Asian ethnicity, these levels are often about right: Cyan - 8 / Yellow - 50 / Magenta - 30.
That's it, lesson 7 finished! You now know how to apply both automatic and manual colour corrections in Curves, using the pipettes and colour channels. You can also use the colour correction features in Camera Raw. Finally, you've learnt how to use the eye-dropper tool alongside curves to precisely correct skin tone.
So, that brings to an end my 7-part primer series on Photoshop. I really hope you enjoyed it! But don't worry, you can now move on to all the other cool Photoshop tutorials on Photography Art Cafe for creating amazing images.
Now you've reached the end of this Photoshop Tutorials For Beginners series, please share your comments at the bottom...
For a beginner-friendly book with step-by-step Photoshop tutorials, I recommend "Photo Nuts and Post" by Neil Creek.
Photoshop Tutorials For Beginners