The steps
To begin, we’ll locate the black point in the sample image shown below. Feel free to use this image, or use one of your own to follow along with this tutorial.
Original Unmodified Image
Locate and set the black point
Open the image in Photoshop, and set the Image Mode to 16 bits by selecting Image | Mode | 16 Bits / Channel. Setting your image to 16 bits is optional, but I always work in 16 bit mode to minimize information loss.
Click on the “Create a new fill or adjustment layer” icon, and select “Threshold.”
Selecting the Threshold Option
In the Threshold dialog box, move the adjustment slider all the way to the left. Next, slowly drag the adjustment slider back to the right until black areas begin to appear in the image.
Threshold Dialog Box and Adjustment Slider
When some people apply this effect, they drag this slider to the right until just a few black dots appear on the screen—this is incorrect because these small black spots typically don’t contain any color information. For example, these black spots are equivalent to RGB 0,0,0—they aren’t actual blacks, they are just void of color, and as such, they are also lacking the color contamination that we are attempting to remove. For this reason, it’s important that you move the Threshold adjustment slider until you can see actual blacks.
So how can you tell when the actual blacks are showing? You can’t be 100% certain, but moving the adjustment slider to the right until you begin to see some “form” in the image is a good start. You can also temporarily turn off the visibility of the Threshold layer by clicking on the eyeball icon—this will reveal the original image, which should give you a good idea of where the blacks are in the image (be sure to turn the layer’s visibility back before you make further adjustments to the Threshold).
The Layer Visibility Icon
Once you’ve identified some blacks in the image, select the Color Sampler Tool. If you don’t see this tool, click and hold on the Eyedropper Tool, and in the resulting sub-menu, select the Color Sampler Tool. Using the Color Sampler Tool, click once in the area that you’ve determined to be black to set the Color Sampler point. If you happen to miss the spot you were trying to click on, you can drag the point you placed to the correct location by clicking and holding your mouse button down on the point while you drag.
Selecting the Color Sampler Tool
It may be helpful to use the Zoom Tool to zoom in on the image to get a better idea of where you’re clicking. The easiest way to zoom in, is to press and hold the “Z” key while you click on the image with your mouse. To zoom out, press both the “Z” key and the Option key (PC: Alt) while you click.
The next step is to create a Curves layer that will contain this black point. Click on the Curves icon in the Adjustments panel, or use the main menu and select Layer | New Adjustment Layer | Curves.
Clicking on the Curves Adjustment Layer Icon
Once the Curves adjustment layer has been added to the layer stack, delete the Threshold layer you created in the previous step by clicking once on the layer to highlight it, and hit the Delete key (PC: Backspace). Don’t omit this important step! Immediately after creating each of our 3 Curves layers, we will need to delete the Threshold layer created in the previous step.
After deleting the Threshold layer, make the upper layer active again by clicking once on it (the Curves layer).
In the Curves dialog box, you will see 3 eyedropper icons. From top to bottom, they represent the black point, the gray point, and the white point.
White Balance Sampling Eyedroppers
Because we are setting the black point in this step, click once on the black point eyedropper icon to select it. Next locate the Color Sampler point we created earlier and click once directly on it to set the black point. When you do this, you’ll probably notice that the curve shown in the Curves dialog box has changed to reflect the black point change.
It may be helpful to use the more accurate version of the selection tool when trying to precisely click on the Color Sampler point. To use this alternative version of the selection tool, simply turn on the Caps Lock key and you’ll see your cursor change. Note that this handy trick works with nearly all of the Photoshop selection tools.
Locate and set the white point
Click on the “Create a new fill or adjustment layer” icon, and select “Threshold.”
In the Threshold dialog box, move the adjustment slider all the way to the right, then slowly drag the slider back to the left until some white areas begin to appear.
Just like when we set the black point, it’s important that you have true whites appear on the screen. You don’t want the whites from a bright window in the background that may have the whites blown-out—these types of whites aren’t actual whites, and they won’t contain the color contamination that we are trying to remove. The same logic applies to specular highlights found in the catch-lights of eyes or the reflection in glassware—these aren’t true whites.
To help you find a location in the image that may have whites, you can reveal the original image by turning off the layer visibility of all layers except for the background layer. The easiest way to do this is to hold the Option key down (PC: Alt) while you click on the layer visibility eyeball on the background layer. When you’re ready to make further adjustments to the Threshold layer, Option+click (PC: Alt+Click) on the background’s eyeball again to make all layers visible again.
Once you’ve identified some whites in the image, use the Color Sampler Tool again to set another Color Sampler point. To add this Color Sampler point, click once in the area that you’ve determined to be white.
Next create a new Curves Layer by clicking on the Curves icon in the Adjustments panel, or use the main menu and selectLayer | New Adjustment Layer | Curves. Once this new Curves Layer has been created, delete the Threshold layer you created in the previous step by clicking on the layer once to highlight it, and hit the Delete key (PC: Backspace).
After deleting the Threshold layer, make the upper layer active again by clicking once on it (the Curves layer).
Because we are setting the white point in this step, click once on the white point eyedropper icon in the Curves dialog box to select it. Next locate the white Color Sampler point we created earlier and click once directly on it to set the white point.
Locate and set the Gray point
Setting the gray point is similar to setting the black and white points as we did earlier, but there’s a couple of intermediate steps we need to make. Start by creating a new layer by either clicking on the new layer icon, or using the keyboard shortcut Shift+Cmd+N (PC: Shift+Ctrl+N).
Clicking the “Create a new layer icon”
Next open the fill dialog box by using the keyboard shortcut Shift+Delete (PC: Shift+Backspace), and select the option to fill this layer with 50% Gray and click on OK.
The Fill Dialog Box
Once this new layer is filled with 50% gray, change the blend mode to Difference.
Selecting the Blend Mode option
Selecting the Difference Blend Mode
Add a new Threshold adjustment layer by clicking on the “Create a new fill or adjustment layer” icon, and selecting “Threshold.”
In the Threshold dialog box, move the adjustment slider all the way to the left. Next slowly drag the adjustment slider back to the right until gray areas begin to appear. There’s no need to be careful that you select actual grays—because the underlying layer is filled with 50% gray, and its blend mode is set to Difference, the only colors that will appear on the screen will be gray. Because of this, you can stop dragging the adjustment slider when just a few small gray spots appear.
Because the layer is filled with 50% gray, and the Difference blend mode is applied to this layer, only grays will appear when the Threshold slider is adjusted. You can verify this yourself by creating a new Photoshop document. Fill the background layer with black, and then add a new layer filled with 50% gray, and set this layer’s blend mode to Difference. When you do this, the only color you will see will be gray. For more information on Blend Modes and their mathematical formulas, read my article “Photoshop Blend Modes Explained.”
Once again use the Color Sampler Tool to set a Color Sampler point on the area that you’ve decided to use as your gray point.
Next create a new Curves Layer by clicking on the Curves icon in the Adjustments panel, or use the main menu and selectLayer | New Adjustment Layer | Curves.
Once this new Curves Layer has been created, delete both the Threshold layer and the layer with the 50% fill that you created in the previous step by clicking once on the layers, and hitting the Delete key (PC: Backspace).
After deleting the Threshold and Fill layers, make the upper layer active again by clicking once on it (the Curves layer).
Because we are setting the gray point in this step, click once on the gray point eyedropper icon in the Curves dialog box to select it. Next locate the gray Color Sampler point we created earlier and click once directly on it to set the gray point.
- Use Cmd+H to hide/show the Color Sampler points (PC: Ctrl+H)
- Delete sample points by Option+Clicking on a sample point with the Color Sampler tool (PC: Alt+Click)
Below is an example of what the layer stack in Photoshop should look like. There should be 3 separate Curves layers, one for each of the white balance color points we set. If you want to make any further adjustments to the image, you have the option of adjusting the Opacity for any of the 3 Curves layers. I should also probably mention that it could be considered a “best practice” to name your layers for easy identification. While I do typically name my layers when working on more complex projects, it’s not really necessary for this procedure. After you’ve done this a few times, and you always apply the color sampler points in the same order, you just “know” which layer is which.
Example of the Final Photoshop Layer Stack
That’s it! You’ve just successfully corrected the white balance for your image!
Before
Original Unmodified Image
After
Final Image with White Balance Adjusted
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