WWW5: graphics on the Web


Computer Graphics Metafile:

Computer Graphics Metafile (CGM) is a formally agreed standard. it is a 2D vector graphic and therefore particularly suited for drawings. CGM files are smaller than images.
CGM files can either be created by using applications such as corel draw or via converters. CGM files have their own MIME type and currently need an external viewer. in the future, plug-ins for Web browsers may become available. for more information choose this .


Portable Document Format:

Portable Document Format (PDF) is a proposed standard from adobe. it is the EPS equivalent for graphics. PDF may include text, graphics and images, the later might be in a compressed format.

this talked focused on the problem of how to provide true colors on different screens or even different types of output devices. colors need to be very accurate for example in advertisements, especial if it comes to fashion or cosmetics. but also in scientific publications, it might be important to provide true colors. the color on the screen does not only vary from one brand to another, but might also change if the light or the background varies.
adobe tries to solve the problem by providing a device dependent transformation of the colors on the input device AND on the output device. but the data that will be transferred over the net shall be in a standardized format. this would allow to transform the data to any output device as long as the transformation process is known for that particular output device.


Portable Network Graphics:

Portable Network Graphics (PNG) shall become a new standard (a formal RFC exists already), the proposed MIME type is image/png. it is fast and optimized for data transfer over the network, because it is simple, robust, flexible and extendable. in contrast to GIF, PNG is legally unencumbered. PNG provides loss-less data compression. it can index color, grayscale or truecolor and supports gamma correction. data may be encoded from 1 to 16 bits per color. since PNG provides 7 pass interlacing, images will appear much faster and will transform from a rough to a more detailed picture smoothly. data files contain metadata as text.


back to WWW5 main document.


WWW5 graphics / 07-jun-96 (ra) / reto ambühler