From time to time it's necessary to cut out the background of an image before importing into a document or web banner, for example. In Photoshop this is a pretty straight-forward process, known in the printing industry as deep etching. It is often used where you need to separate an item like a logo or a head shot from its background.
Adobe Photoshop provides various selection tools useful to this process. In order to perform many operations in Photoshop we have to select a group of pixels which represent the object. When the selection is complete we can do just about anything with it, from changing colours and tones to retouching or copying the image across into another file.
We usually select the easiest element first, then modify the selection. For example, where the original image has a plain white or colour background the selection process is easy. In these cases it's usually a simple matter of selecting the white/colour background with the Magic Wand tool together with a Feather value of 1 or 2 pixels. Often it's necessary to tidy up by adding or subtracting from this initial selection. It may also be necessary to switch to the Polygonal Lasso tool, as well as pressing Shift to add to the selection. Alternativley we can press Alt key (or in the Macintosh version of Photoshop press the Option key) in order to subtract from the selection. In this way we use a variety of selection tools within the one selection operation.
When we are satisfied with this selection, we go to the top Select drop-down menu, and choose Inverse in order to select the logo or object itself. We then go to the Edit menu and choose Copy or Cut. Then we select Edit and Paste. This results in the creation of a new layer. Toggle the eyeball visibility icon off in the Layers panel to make the background layer invisible. This reveals the deep etching operation. Note also the transparent element of the layer which is indicated by a grey checker-board pattern. If the result is satisfactory we simply delete the bottom background layer by dragging it to the bottom right Trash icon, or by right-clicking on the layer and choosing Delete.
The last step is to save the image as a new file format. There are many to choose from, with the exception of the JPEG format. Were we to save it as a JPEG a white background will reappear, since this particular file format does not support transparency. The format we choose often depends on what's required by the recipient. For example, printing companies often request TIFF files since they have good high printing resolution. They can be up to ten times the size of a JPEG, but will print much better. On the other hand web professionals often request JPEGs or PNGs. PNGs are better than JPEGs due to the support for transparency. PNG 8 has 2 colours (256), whilst PNG 24 has millions of colours. In the end it's best to ask the web people which format they prefer.
Tom Gillan has been training Photoshop to corporate clients in Sydney for seven years.Visit Design Workshop Sydney and get your Adobe Photoshop online course .