I have long thought that Preview is as powerful as Photoshop. At least for the basic tasks. Today’s post is going to show you how to edit an image so you can have a transparent background. This is particularly useful if you have an image with a white background and you want to remove it so it becomes transparent. This image can then be used in your various documents within iLife or iWork. I use this for image which I place in iMovie.
Making A Transparent PNG
To make a transparent PNG, open the image in question within Preview.
From the menubar select View > Show Edit Bar. This bring up a pane on image editing tools. From this menu bar select the little magic wand tool.
Use this tool to click and drag on the colour you want to remove from the image. If it is a white colour, select the white and then drag the mouse. It takes a couple of goes to get the knack right. But as you drag the image will slowly begin to turn red. This is the areas of the image that will be selected for deletion. It will only select the areas connected, the more you drag the more colour that is selected.
When you release the mouse a selection area will be shown on the image by the moving black dotted line. Press delete and the area that is selected will be removed. You may get a message asking your to change the file format to PNG, accept this change. Repeat this process for all of the areas on an image you want to delete.
The final step is to save the image. Go to File > Save As and select PNG from the drop down list. Ensure the Alpha option is selected. This is used for making png files transparent.
This tip works best with simple images. However you can do it with more complex pictures. You just need to select the area, delete and then select a different area. Repeat until you get the desired effect.