Because the majority of Web browsers recognize GIF and JPEG images, these two formats are used most often for saving Web images. Newer versions of the Web browsers can also recognize the more recent PNG format, and many Web browsers also support Windows Wireless Bitmap (WBMP) and iMode formats, which are popular to display when using wireless devices.
When you save images for the Web, there are three major issues to consider: layers, color depth, and file size.
Because none of the current Web browsers can display layered images, you need to flatten an image before saving it for the Web. Flatten it by choosing Layers > Merge > Merge All (Flatten).
Some computers are only capable of displaying up to 256 colors. If an image on a Web page contains more colors, the Web browser uses its own dithering method to display the image. This can produce color distortion. If you reduce the color depth of the image to 8 bits (256 colors) before placing it on your Web page, its appearance will be more consistent.
File size affects the majority of users accessing a Web page. As the size of an image file increases, it takes more time to download, so viewers have a longer wait. Use a file format that reduces the image size most efficiently while keeping the quality as high as possible.
Choose from the following file formats when saving image for use on the Web:
GIF Use this format to compress line art and images with areas of similar colors. It supports 8-bit (256) color. There are two versions of GIF: 89a, which can save transparency and animation information, and 87a, which cannot. Both are recognized by most browsers and use lossless compression.
JPEG Use this format to compress photographic images. It supports 24-bit (16.7 million) color, uses lossy compression, and is recognized by most browsers.
PNG This format compresses most images efficiently. It supports up to 24-bit (16.7 million) color and uses lossless compression, but it is recognized by most browsers, however many features of this format are not available.
Wireless Bitmap (WBMP) This format is used with many wireless devices. The images are black and white and have lossless compression.
Lossy vs. Lossless compression: Lossy compression is a compression method that eliminates data to reduce the file size, while lossless compression retains all of the original image data and reduces the file size by storing patterns of pixels in the image.
Previewing images in a Web Browser
Saving Images for use with Animation Shop