Creating background matting in JPEG images

When creating a JPEG from an original image that contains layer transparency, you must matte the image against a matte color. Since the JPEG format does not support transparency, blending with a matte color is the only way to create the appearance of background transparency in a JPEG. Fully transparent pixels are filled with the matte color, and partially transparent pixels are blended with the matte color. When the JPEG is placed on a Web page with a background that matches the matte color, the image appears to blend with the Web page background.

To create a matted JPEG image:

1 Open or create an image that contains transparency, and choose File > Save for Web.

2 In the Save For Web dialog box, select JPEG as the optimization format.

3 Select a color from the Matte pop-up menu: None, Eyedropper (to use the color in the eyedropper sample box), White, Black, or Other (to select a color using the color picker).

Note: When you select None, white is used as the matte color.

Optimizing Images for the Web > Making transparent and matted images > Creating background matting in JPEG images