Making transparent and matted images

Transparency makes it possible to place a nonrectangular graphic object against the background of a Web page. Background transparency, supported by GIF and PNG formats, preserves transparent pixels in the image. These pixels allow the Web page background to show through in a browser.

Background matting, supported by GIF, PNG, and JPEG formats, simulates transparency by filling or blending transparent pixels with a matte color that you choose to match the Web page background on which the image will be placed. Background matting works better if the Web page background will be a solid color, and if you know what that color will be.

The original image must contain transparent pixels in order for you to create background transparency or background matting in the optimized image. You can create transparency when you create a new layer.

Note: You can use the magic eraser tool or the background eraser tool to easily create transparency in an image. (See Using the magic eraser tool and Using the background eraser tool.)

Optimizing Images for the Web > Making transparent and matted images

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