We're able to remove solid blocks of color using the Instant Alpha tool in Preview.
Note
The Instant Alpha tool can be used to remove solid blocks of color from images. It works by detecting similar shades of a color you select and replacing those pixels with a transparent color.
1. If you haven't already, open Preview.
2. Now open the
grass-blades.pngfile, included in theDino Storefolder of the demo assets you download. You should see some green blades of grass on a cream background.3. This cream background will interfere with the background image of our iAd, so we're going to remove it. Before we continue, make sure that Show Image Background in the View menu is checked. This will allow us to see where our image ends and which parts are transparent.
4. Click on the small arrow to the right of the Select button, above the image, and select Instant Alpha, as shown in the following screenshot:
