The Crop tool is generally used to crop or make an image smaller, but this trick shows you how to add to the canvas area. This is a nice way to add a larger border or white space around an image. It works well for posters and you could also easily adapt it to create a polariod style image.
1. Open an image that you want to add white canvas area to.
2. Press D to set the Foreground and Background colours to Black and White respectively.
3. Zoom right out so that you can see the grey desktop area around the image.
4. If you are working on an image that has more than one layer, make sure that the Background layer is the active layer.
5. Select the Crop tool (C) and drag out a marquee from the top left corner of the image to the bottom right corner. At this stage it doesn’t matter if the whole image is not selected.
6. Drag out each corner or middle handle so that the cropping area is now outside the image and takes in some of the grey desktop.
7. Press Enter (PC) or Return (Mac) to finalise the Crop. The grey desktop area that you include in the crop area will be converted to extra image canvas and will appear white because that is the current background colour.
8. (Optional) Add some text to create a poster or advertisement. In this example I used Century Gothic, size 14, bold for the headline, and Century Gothic, size 10, regular for the tagline.