There are a lot of different ways to do a collage. You could do a whole bunch of different sized images here and there. I decided to go with a more uniform type of look. I am going to use 3 images that are all the same size. I have found for this project, making the width of your individual photos about 55% of the width of the document seems to work well. For example, if you are creating 1024x768 image, you would want the width of your 3 photos around 550 pixels. This is not set in stone and you can certainly play with these numbers to get the right feel for your collage. The resolution for all of my images is set to 72 pixels/inch for viewing on a computer monitor. If you were planning on printing this, you would want to increase that to 150 pixels/inch or higher.
Open a new document of whatever size you would like to make your collage. For this tutorial I am making mine 600x400. Resize your images accordingly (Image/Image Size), and then drag them into your collage document with the move tool. Now you should have a background layer and three layers for your 3 pictures.
Fill your background with whichever color you like. I am going to put a white border around the pictures which you will not be able to see if you leave the background white. I am filling with a radial gradient of a light yellow to bright yellow.
Next, make sure each of your photo layers are lined up on top of each other. We are going to create a rounded corner effect, and if they are all in the same place we will only have to select once. This will also give each of the photos the same effect.
Once you have them all lined up (you should only be able to see the top layer), select the Rounded Rectangle Tool and set the radius to 10 Px. Make sure your top layer is highlighted in the layers palette. Make a selection as shown below.
Right click in the middle of the picture and choose "Make Selection". Set the feather radius to 5 pixels and click ok. You should now see the "dancing ants" indicating it is a selection. Choose Select/Inverse from the menu bar and hit delete. You should now have something that looks like this.
Now highlight the next layer down and hit delete. Do this one more time on your bottom picture layer (not the background). Hit Control+D to deselect. Now you can move these pictures around to see how they look.
Highlight the top layer again and select Layer/Layer Style/Blending Options. This should open the Blending Options window. I am going to add a stroke and a drop shadow. Here are the settings I used.
And here is the result. Do the same thing to your other picture layers.
Now I am going to move them around a bit, and rotate a couple of them. Move one picture to the upper left corner. Now select Edit/Transform/Rotate. Grab one of the handles that appear and rotate the picture a little to the left. Hit enter to commit the transformation.
Do another picture in the upper right corner and then one in the middle on the bottom. Play around with it a bit until you get exactly what you are looking for. Here is my finished collage.
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