Every adjustment layer in Photoshop automatically comes with its own layer mask, allowing you to selectively apply the adjustment to specific areas of your image. You manipulate this mask using black, white, and shades of gray.
Here's how to mask an adjustment layer:
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Create an Adjustment Layer: Select the layer you want to adjust. Go to the "Layers" panel (Window > Layers if you don't see it) and click the "Create new fill or adjustment layer" button at the bottom. Choose the type of adjustment you want to make (e.g., Brightness/Contrast, Curves, Hue/Saturation).
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Understanding the Layer Mask: Once the adjustment layer is created, you'll see a white rectangle next to the adjustment icon in the Layers panel. This is the layer mask.
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Painting on the Mask:
- White: White on the mask means the adjustment is fully visible and applied to the corresponding area of the image below.
- Black: Black on the mask means the adjustment is completely hidden from the corresponding area of the image below.
- Grayscale: Shades of gray create partial transparency. Lighter grays allow more of the adjustment to show through, while darker grays allow less.
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Using the Brush Tool:
- Select the Brush Tool (B).
- Set your foreground color to black or white. You can quickly switch between black and white using the "X" key.
- Make sure the layer mask thumbnail is selected in the Layers panel (click on it). You will see a white border around it. This ensures you are painting on the mask, not the adjustment itself.
- Now, paint on your image. Black will hide the adjustment in the painted areas, and white will reveal it. Adjust brush size, hardness, and opacity for finer control.
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Using Gradients:
- Select the Gradient Tool (G).
- Choose a gradient that transitions from black to white.
- Click and drag on the image while the layer mask is selected to create a smooth transition between the adjusted and unadjusted areas.
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Using Selections: You can create selections and then fill them with black or white to create more precise masks.
- Use the Selection Tools (Marquee, Lasso, Magic Wand, etc.) to create a selection around the area you want to affect.
- Make sure the Layer Mask thumbnail is selected in the Layers panel.
- Go to Edit > Fill. Select Black or White from the "Use" dropdown menu.
- Deselect by going to Select > Deselect
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Disabling the Mask: You can temporarily disable the mask by right-clicking on the layer mask thumbnail and choosing "Disable Layer Mask." The adjustment will then apply to the entire image. Re-enable the mask to restore its effect.
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Viewing the Mask: To see the mask directly on the image, Alt/Option+click on the layer mask thumbnail. Alt/Option+click on the thumbnail again to return to the normal view.
In summary, adjustment layer masks allow you to apply image adjustments non-destructively, giving you precise control over which parts of your image are affected. Mastering layer masks is a fundamental skill for any Photoshop user.
