Acorn: Fun with Layer Masks

Fun with Layer Masks

Layer Mask Example Using Magic Wand

To start, add an image of a starfish and an image with some boats to Acorn in separate layers. The layer with the starfish needs to be above the layer with the boats.

Big Starfish-1_resized.jpeg

Next, select the layer that includes the starfish and add a layer mask by clicking on the cogwheel and selecting "add layer mask". The layers palette should now look like this:

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Click on the layer mask to begin working on it. You will know the layer mask is selected when a black line appears towards the bottom of the mask. Now "mask" everything in the starfish image except the starfish. To do this, select the magic wand tool and set the wand tolerance to around 90. Click on the water around the starfish to select it, then choose Edit ▸ Clear to allow the boat layer below to show through. Don't forget to deselect after doing this by clicking ⌘D.

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Right now the layer mask is doing its job of exposing exactly the part of the layer below that is situated under the starfish. The starfish can be blended into the boat exterior by decreasing the opacity of the starfish layer to about 70%. Notice how the starfish and the boat layers were not actually altered ?

Layer Mask Example Using Gradients

You can have a lot of fun combining images seamlessly with layer masks using gradients. Similar to the previous example, open the images you want to combine in Acorn. Place the image that you wish to mask areas from in the top most layer. In this example a sunrise skyline will be replaced with outer space.

Yemanja - Lost Souls.jpeg Hubble Sees 'Island Universe' in the Coma Cluster.jpg

Following steps outlined previously, add a layer mask to the layer you wish to conceal areas on. Here a layer mask will be added to the sunrise skyline. Select the layer mask by clicking on it. Now add a gradient to the layer mask. Click on the gradient tool in the tools palette and choose "linear gradient". Make sure the colors present on your tools palette are black and white. The goal is to have outer space show through on the sunrise image from the horizon to the top of the image, so add a gradient spanning this section of the image. The white line below is showing the span of the gradient.

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Once the gradient is applied, the layer below will be exposed! Have some fun adjusting the opacity and blending settings to get things looking just right.

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Layer Mask Example Using 'Paste Into'

Another layer mask technique is using "Paste Into". With Paste Into you select all or part of one image, then select the area(s) on another image that you would like the initial image to appear on. Since this uses layer masks neither image is being altered, so it is easy to go back and change things later. As an example, take a television that is showing a soccer game. The goal is to change the television screen to show an image of a roller derby game.

Lounge Setup.png

Open both images in Acorn with the television image in the top layer, and the roller derby image in the layer below it. In this example the entire roller derby image will show up on the television. Click on the roller derby image layer. Choose Select ▸ Select All (⌘A), then make a copy Edit ▸ Copy (⌘C). Now go ahead and clear your selection (⌘D). Next, click on the layer with the television image. Make a layer mask with the part of the image with the soccer game. To do this, go to the tools palette and pick one of the selection tools. With this particular example it will be easiest to use the polygon selection tool (for more information on selection tools read Making Selections. Using the polygon tool, outline the screen of the television.

Now for the fun part! Go to Edit ▸ Paste Into (⇧⌘V) and the selected part of the roller derby image will show through the layer mask making it appear to be on tv. Using the move tool, move the roller derby image around until you get it lining up where you want it. If the roller derby image is too large or small, click on that layer and use Layer ▸ Rotate and Transform ▸ Scale and Rotate (⌘⇧T) to fix things.

Lounge Setup.acorn

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