Hidden Algorithms for Easy Color Correction in Photoshop
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A hidden algorithm inside the Curves adjustment layer gives you one-click auto color correction in Photoshop.
The Auto button in Curves applies an automatic adjustment to your photo. In my opinion, the default algorithm that Photoshop uses is not the best.
Luckily, there are a few others you can select. Hold Alt (Windows) or Option (macOS) and click Auto to open the Auto Color Correction Options.
My favorite algorithm is Find Dark & Light Colors. It removes a color cast and adds contrast with a single click.
This tutorial is for anyone who needs to color correct a photo fast, or match a subject to a new background in a composite.
By the end, you will color correct an image with one click and fix the photos that Auto cannot solve. You will also color match a layer to any background.
Everything here works in Photoshop 2021 or the latest version.
Key Takeaways
- By default, the Auto button in Curves uses Enhance Brightness and Contrast. It changes brightness and contrast only, so a color cast stays in the photo.
- Find Dark & Light Colors with Snap Neutral Midtones checked fixes most color casts in one click.
- Check Save as defaults once, and every future click on Auto uses the algorithm you picked.
- Click Auto before you use the gray point eyedropper. Auto adds the contrast that the eyedropper alone leaves out.
- To color match a composite, uncheck Snap Neutral Midtones and sample the Shadows and Highlights target colors from the background.
- If your layer turns white when you sample a target color, the Layer Mask thumbnail is active. Click the Curves thumbnail first.
Table of contents
- What You Will Learn
- Requirements
- Keyboard Shortcuts
- How Auto Color Correction in Photoshop Works
- Step 1: Add a Curves Adjustment Layer and Click Auto
- Step 2: Open the Auto Color Correction Options
- Step 3: Pick the Best Auto Color Algorithm
- Step 4: Save Your Default Auto Color Correction
- Step 5: Fix a Color Cast When Auto Color Correction Fails
- Step 6: Clip a Curves Layer to Color Match a Composite
- Step 7: Select the Curves Thumbnail, Not the Layer Mask
- Step 8: Set the Shadow and Highlight Target Colors
- Step 9: Adjust the Contrast with the RGB Curve
- Frequently Asked Questions
- Let Auto Color Correction Do the Hard Work
- Related Links
What You Will Learn
- How to open the Auto Color Correction Options in a Curves adjustment layer
- Which algorithm gives you the best automatic color correction
- How to set that algorithm as your default
- How to use the gray point eyedropper when Auto is not enough
- How to color match a layer to a background with target colors
- How to finish the match with the RGB curve
Requirements
Before you start
- Photoshop 2021 or the latest version
- A photo with a color cast, or the practice files below
Practice Files
Download the images used in this tutorial and follow along step by step.
Keyboard Shortcuts
| Action | Windows | macOS |
|---|---|---|
| Open the Auto Color Correction Options | Alt click the Auto button | Option click the Auto button |
| Create a Clipping Mask | Ctrl Alt G | Command Option G |
| Sample a color from the image while the Layer Mask is active | Ctrl click the image | Command click the image |
How Auto Color Correction in Photoshop Works
Auto color correction is a one-click adjustment. Photoshop analyzes your photo and sets the curve for you.
You will find the Auto button in the Properties panel of a Curves adjustment layer.
Behind that button there are four algorithms. An algorithm is the set of rules Photoshop follows to analyze your photo. Photoshop uses one at a time.
| Algorithm | What it does |
|---|---|
| Enhance Monochromatic Contrast | Adds contrast to all the colors equally. The colors stay the same, so a color cast stays too. |
| Enhance Per Channel Contrast | Adds contrast to the red, green, and blue channels separately. It can remove a color cast or add one. |
| Find Dark & Light Colors | Finds the average darkest and lightest colors in the photo and uses them to set the contrast. My favorite for color correction. |
| Enhance Brightness and Contrast | The default. It adjusts brightness and contrast only. |
Below the algorithms, you will see the Snap Neutral Midtones checkbox. It finds a color that is almost neutral and makes it a true neutral gray.
At the bottom, the Target Colors set the colors Photoshop uses for the Shadows, Midtones, and Highlights. You will use them later to color match.
Step 1: Add a Curves Adjustment Layer and Click Auto
Open the practice document and start with example number one. As you can see, this image needs color correction.
In the Layers panel, click the New Adjustment Layer icon and select Curves.
The practice document has several layers. Click-and-drag the Curves layer down so it sits directly above example number one.
In the Properties panel, click the Auto button. Photoshop applies an automatic color adjustment to the image.
With the default algorithm, it does not give you the best result.
Step 2: Open the Auto Color Correction Options
Hold Alt (Windows) or Option (macOS) and click the Auto button.
This brings up the Auto Color Correction Options. By default, Photoshop uses Enhance Brightness and Contrast.
Click on the other algorithms to see the result. The image updates as you click, so you can compare them on your own photo.
Step 3: Pick the Best Auto Color Algorithm
Select Find Dark & Light Colors. As you can see, it does a fantastic job.
Then check Snap Neutral Midtones to get a better color balance.
A color cast is an unwanted tint that covers the whole photo. If you want a manual method, see how to remove a color cast in Photoshop.
Step 4: Save Your Default Auto Color Correction
Check Save as defaults in the bottom-left corner of the dialog. Then press OK.
Next time you create a Curves adjustment layer and click Auto, Photoshop applies that algorithm.
In my opinion, it does a much better job most of the time.
Tip: I encourage you to change your default algorithm. You will color balance your images faster, because one click on Auto is all it takes.
Step 5: Fix a Color Cast When Auto Color Correction Fails
The next example has a similar issue. The image is too warm, and it needs to be color corrected.
Create a new Curves adjustment layer and click Auto.
In this case, Photoshop did not color correct the image. It has color correction issues that are too difficult for Auto to solve.
In the Properties panel, select the center eyedropper. That is the gray point eyedropper, and it sets the midtones.
Click anywhere on the image that should be a neutral gray. These columns should be white. They should not have any color cast.
Click on the columns. Photoshop removes the color cast, and the image looks much better.
You are probably thinking, why not click with the gray point eyedropper to begin with and skip Auto?
If you do that, Photoshop does remove the color cast. But the image is still washed out.
That is the advantage of clicking Auto first. Photoshop adds contrast to the image automatically.
The best thing about this method is that you can experiment. Click on different areas of the image, and stay with the result you like best.
The same eyedropper can also fix skin tones in Photoshop with one click.
Step 6: Clip a Curves Layer to Color Match a Composite
Next, use the same algorithm to color match a layer.
This technique works great when you are compositing and the background has a strong color cast or color tint.
In this example, the jet needs the same color cast as the sky to look more realistic.
Create a new Curves adjustment layer above the jet. At the bottom of the Properties panel, click the icon with the down-pointing arrow.
That arrow represents a Clipping Mask. The adjustment layer now affects only the layer directly below it, so your changes only affect the jet.
Tip: You can also create a Clipping Mask with CtrlAltG (Windows) or CommandOptionG (macOS).
I cover this color matching method on its own in how to match colors in Photoshop.
Step 7: Select the Curves Thumbnail, Not the Layer Mask
Before you go any further, look at the Curves layer in the Layers panel. It has two thumbnails.
Click on the Curves thumbnail on the left. The focus, the white outline, should be around that thumbnail and not the Layer Mask.
You are about to sample colors from the image. With the Layer Mask thumbnail active, Photoshop samples the white of the mask instead, and the entire jet turns white.
Tip: Already inside the Color Picker? Hold Ctrl (Windows) or Command (macOS) and click to select the actual color in the image.
Step 8: Set the Shadow and Highlight Target Colors
Hold Alt (Windows) or Option (macOS) and click Auto to bring up the Auto Color Correction Options.
Earlier, the target colors were black and white. That is what you want when you neutralize an image to remove a color cast.
In this case, you want to introduce a color cast so the jet matches the background. Start by unchecking Snap Neutral Midtones.
Click the Shadows swatch to open the Color Picker. Then click on a shadow color in the background that has the color cast. In this example, it is an orange.
You can drag down in the Color Picker to make the color darker, or drag the hue slider to adjust it. Be more concerned with the color than the contrast for now. Press OK.
Next, click the Highlights swatch and click on the highlights in the background.
Do not use white or a specular highlight, which is the brightest reflection in a photo. Pick something that represents the highlight colors, like the yellow in this sky.
If it is too yellow, too bright, or too dark, adjust it in the Color Picker. Here, the highlight works better closer to orange. Press OK.
Press OK to close the Auto Color Correction Options.
Note: Photoshop asks if you want to save the new target colors as defaults. In most cases, you do not want to do this. Press No.
Step 9: Adjust the Contrast with the RGB Curve
The shadow colors and the highlight colors are in place. Next, work on the contrast.
In the Properties panel, use the RGB curve. Click-and-drag the lower part of the curve down to make the shadows darker.
Then click-and-drag the upper part of the curve up to make the highlights brighter.
That gives the jet the right contrast for this scene. Click the eye icon on the Curves layer to see the before and after.
Frequently Asked Questions
Auto color correction is a one-click adjustment that analyzes your photo and sets the tones and colors for you. You apply it with the Auto button in a Curves adjustment layer. The result depends on which of the four algorithms is active.
Create a Curves adjustment layer and open the Properties panel. Hold Alt on Windows or Option on macOS, then click the Auto button. The Auto Color Correction Options dialog opens.
Find Dark & Light Colors gives the best result most of the time. Check Snap Neutral Midtones with it to get a better color balance. The default, Enhance Brightness and Contrast, does not remove a color cast.
Snap Neutral Midtones finds a color in your photo that is almost neutral and makes it a true neutral gray. That removes the color cast from the midtones. Uncheck it when you want to add a color cast, like when you color match a composite.
Open the Auto Color Correction Options and select the algorithm you want. Check Save as defaults, then press OK. From then on, the Auto button uses that algorithm every time.
Some photos have color issues that are too difficult for Auto to solve. After you click Auto, select the gray point eyedropper in the Properties panel. Then click on an area that should be neutral gray or white.
The Layer Mask thumbnail is active, so Photoshop samples the white of the mask instead of the photo. Cancel, click the Curves thumbnail in the Layers panel, and try again. You can also hold Ctrl on Windows or Command on macOS and click the image.
Yes. Clip a Curves adjustment layer to your subject and uncheck Snap Neutral Midtones. Then set the Shadows and Highlights target colors by clicking on the background. Finish with the RGB curve to adjust the contrast.
Let Auto Color Correction Do the Hard Work
By now, you can see the power of the Auto Color Correction Options. They are one of the best tools for color correcting and color matching.
Change your default algorithm once, and auto color correction in Photoshop becomes a single click. When a photo needs more, the gray point eyedropper is one more click.
Watch the full tutorial above to see every step in real time.
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