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PNG
The Portable Network Graphic, or PNG, is the most
versatile of the web graphic formats. However, not all
web browsers can take full advantage of PNG
characteristics. A PNG supports up to 32-bit color, can
contain transparency or an alpha channel, and can be
progressive.
Web format comparison
Color depth
Compression
Transparency support
Advantages
Disadvantages
Typical Uses
Compression
PNG compression is lossless, even in high color depths.
It compresses across rows and columns of pixels, yielding
better compression than GIF, which only scans rows. A
PNG can compress more than a GIF or JPEG of the
same color depth and quality.
The PNG format is best suited for creating complex live
transparency, high-color graphics, or better compressed
low-color graphics.
GIF
8-bit maximum
Lossless; compresses
solid areas of color
Yes
Lossless compression
Transparency
Maximum of 256 colors
Does not compress
gradient colors well
Cartoon images
Logos
Animated banners
JPEG
Up to 24-bit
Lossy; compresses subtle
color transitions
No
Ability to control quality
loss in compression
Excellent compression of
photographic images
No transparency
Loss of quality when
compressed
Scanned photographs
Images with complex
textures
Images with complex
gradient colors
Importing and Exporting
PNG
Up to 32-bit
Lossless
Yes
Lossless compression
Alpha transparency
High color support
Not completely
supported by common
browsers without using
plug-ins
Images with high
numbers of colors
Complex, live
transparency
105
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