What is the PNG format, and how does it differ from GIF or JPEG?
The Portable Network Graphics (PNG) format, pronounced “ping,” emerged after a 1994 patent controversy over the GIF format appeared to threaten GIF’s widespread use. Although GIF is still with us, PNG format development is continuing. PNG has a lot of the same features as GIF, including indexed color palettes, interlacing and transparency (in GIF89a), and lossless compression (unlike JPEG, which sacrifices some image data in reducing file size). It also has some features that GIF doesn’t have, such as support for 48-bit color and an alpha channel for masks–and, as you might expect, its compression scheme is not patented. PNG also automatically adjusts graphics for gamma correction to compensate for cross-platform differences in brightness and contrast, which is a major bonus for designers of Web graphics. It still remains to be seen whether PNG will become a popular Web graphics standard, given the widespread use of and browser support enjoyed by both GIF and JPEG. Not all image edito
The Portable Network Graphics (PNG) format, pronounced “ping,” emerged after a 1994 patent controversy over the GIF format appeared to threaten GIF’s widespread use. Although GIF is still with us, PNG format development is continuing. PNG has a lot of the same features as GIF, including indexed color palettes, interlacing and transparency (in GIF89a), and lossless compression (unlike JPEG, which sacrifices some image data in reducing file size). It also has some features that GIF doesn’t have, such as support for 48-bit color and an alpha channel for masks–and, as you might expect, its compression scheme is not patented. PNG also automatically adjusts graphics for gamma correction to compensate for cross-platform differences in brightness and contrast, which is a major bonus for designers of Web graphics. It still remains to be seen whether PNG will become a popular Web graphics standard, given the widespread use of and browser support enjoyed by both GIF and JPEG. Not all image edito
