The page Photoshop Layers provides an introduction to using layers in Photoshop. Here I intend to provide an actual example showing how you can combine several images into one using Photoshop layers. The three images I intend to combine are ones I created in Paint Shop Pro described on the page Manipulating Images.
Here are the three images that I intend to combine into one image using Photoshop:
I began the process by deciding that the map of the UK would form the background layer and so I changed the colour depth of this image to 24 bit colour (Image / Mode / RGB Color) and enlarged the canvas (Image / Canvas Size) to the final size I wanted for the final image.
The next step was to create a new layer in the image (Layer / New) and select the Mode to be used for combining the images. In this instance I want to overlay the map with the photo of myself so that both are visible. To do this I selected Multiply mode. Next I switched to the second image (my photo) and selected the entire image (Select / All). I then used Copy and Paste to copy the selection into layer one of the map image. Finally, I used the Move tool to move the photo to the appropriate position over the map.
Because I used multiply mode, both images are visible with those places where my face overlaps the map appearing greyer than those areas that don't overlap.
To place the circle of track over the image required a completely different approach. I first created a new layer in the map/photo image this time selecting Normal mode.
The next step was to use the Magic Wand tool to select the white area outside of the circle of track (with tolerance set to zero so as to not select the grey rail). I then held down the shift key and continued to use the magic wand tool to select all of the white areas behind the track image. The next step was to invert the selection (Select / Inverse) so that the track is selected but not the background. I then used Copy and Paste to transfer this into the new layer in the map/photo image. Because only the track is selected whatever is not covered by the track still shows through from the other layers.
To finish the image off, I flattened the image (Layer / Flatten Image) and then added some text into the image, and exported the image as a GIF file with transparent background. The resultant image makes a suitable logo for my railway site.
There are a lot of different options in the layer tools regarding the effect that the different layers will have on one another, it is well worth the effort of experimenting with them to see what each does in order to decide which options are most appropriate to achieve the effect that you require.
This article written by Stephen Chapman, Felgall Pty Ltd.