Create Layer Masks from Photoshop CS5 Selections
A layer mask covers areas of your Photoshop Creative Suites 5 image that you want to make transparent and exposes pixels that you want visible. Masks can be based on a selection you’ve created with the selection tools or by painting on the mask itself.
You need to have two images open to follow these steps to create layer masks from a selection:
When combining images, choose Image→Image Size to make sure that the images are approximately the same resolution.
Otherwise, you may create some interesting, but disproportional, effects.
The images are now in separate windows.
Using the Move tool, click one image and drag it to the other image window.
A black border appears around the image area when you drop an image into another image window. By dragging and dropping an image, you automatically create a new layer on top of the active layer.
Hold down the Shift key when dragging one image to another to perfectly center the new image layer in the document window.
Using any selection method, select a part of the image that you want to keep on the newly placed layer and choose Select→Modify→Feather to soften the selection.
Five pixels should be enough.
Click the Layer Mask button at the bottom of the Layers panel.
A mask is created to the right of the layer, leaving only your selection visible.
If you click the Layer thumbnail in the Layers panel, the mask thumbnail shows corner edges, indicating that it’s activated.
While the layer mask is active, you can paint on the mask.
Select the Brush tool and paint black while the mask thumbnail is selected to cover areas of the image that you don’t want to see
You can even change the opacity while you paint to blend images with each other.
Press X to switch to white and paint to expose areas on the image that you do want to see.
To create a smooth transition from one image to another, drag the Gradient tool across the image while the layer mask is selected in the Layers panel.