Photoshop Elements 2020 For Dummies
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Indexed Color in Photoshop Elements is a mode you use occasionally with web graphics saved in GIF or PNG-8 format. When saving indexed color images, sometimes you can create smaller file sizes than RGB that are ideal for using in website designs (because the smaller the file size, the faster a page downloads to the visitor’s browser).

RGB images in 24-bit color (8 bits per channel) are capable of rendering a palette of 16.7 million colors. An indexed color image is an 8-bit image with only a single channel. The total number of colors you get with indexed color can be no more than 256.

When you convert RGB images to indexed color, you can choose to dither the color, which displays the image with an effect much like what you see with bitmapped images. This dithering effect makes the file appear as though it has more than 256 colors, and the transition between colors appears smoother than if no dithering was applied.

On occasion, indexed color images have an advantage over RGB images when hosting the images on web servers: The fewer colors in a file, the smaller the file size. When you prepare images for web hosting, you can choose to use indexed color or RGB color. Whether you choose one over the other really depends on how well the image appears on your monitor.

If you have some photos that you want to show on web pages, you should use RGB images and save them in a format appropriate for web hosting.

If you have files composed of artwork, such as logos, illustrations, and drawings, you may find that the appearance of index colors is no different from the same images in RGB mode. If that’s the case, you can keep the indexed color image and use it for your web pages.

To convert RGB images to indexed color, choose Image→Mode→Indexed Color; the Indexed Color dialog box opens. Several options are available to you, and fortunately, you can preview the results while you make choices. Get in and poke around, and you can see the options applied in the image window.

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