► Note 128

Although there is a PNG counterpart that supports animation—MNG (Multiple-image Network Graphics)—it is not supported by most browsers and therefore is not yet a viable alternative to GIF animation.

Because the creators of PNG knew what didn't work in GIFs, they could plan ahead and make what some call a perfect file format. With that in mind, PNG is particularly good in terms of transparency. Unlike GIF, which only supports 1-bit, or 1-color, transparency, PNG can support multiple levels— and multiple colors—of transparency. Keep in mind that while PNGs using 1-bit transparency are smaller in file size than GIFs, those with multilevel transparency are substantially larger.

Characteristic

Description

Color mode

Restricted to no more than 256 exact colors (8-bit)

Compression method

Lossless

Animation

Not supported

Transparency

Supported (binary)

Interlacing

Supported

File type

Bitmap

Table 10-3 PNG-8 File Format Characteristics

Characteristic

Description

Color mode

Displayed in 24-bit RGB color, also called millions of colors; if the user's monitor isn't set to view 24-bit color, the file is displayed with as many colors as are available

Compression method

Lossless

Animation

Not supported

Transparency

Supported (variable)

Interlacing

Supported

File type

Bitmap

Table 10-4 PNG-24 Format Characteristics

Table 10-4 PNG-24 Format Characteristics

An additional benefit of PNG is its gamma correction. The PNG file format has the capability to correct for differences in how computers and monitors interpret color values. While all these characteristics make PNG well suited for almost any type of web graphic, only some of the newest browsers support it. Unfortunately, this means users of older browsers must download a plug-in to view web graphics saved in the PNG format. This might make the format off-limits for many designers until the majority of users have browsers capable of displaying PNGs.

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