Jan 062012

As we know the short pronounce of portable network graphics is PNG. It is a bitmapped image format and video codec that has used for lossless data compression. Portable network graphics has designed to enhance upon and replace Graphics Interchange Format (GIF) as a picture file format. One of the best advantages of it is not requiring any sorts of patent license.

Also, the PNG has designed to support the palette based pictures like 24-bit, 32-bit RGBA colors, and grayscale images with or without alpha channel. Also, the PNG has been evolved for transmitting the pictures on the Online, and it has not designed for professional image print graphics. This technical process has been approved by the Internet Engineering Steering Group in the year of 1996. If you want to use this sort technical process, then you need to understand how to utilize in an image for perfect print quality. Motivation to make PNG format was in 1995, after that it became known as Lempel Ziv Welch data compression algorithm that is used in Graphics Interchange Format that was patented by the Unisys. Also, there were other problems with GIF format, which made the replacement desirable, and notably the limit of 256colors at the time when the computers display more than 256colors were growing very common.

Though GIF enables for animation, then it was decided PNG must be the single image format. The companion format named Multiple image Network is defined for the animation. In 1996: Version1.0 of PNG specification was been released, and then appeared as the RFC 2083 and it became the W3C Recommendation on 1 October 1996. On, 1998: Version1.1, with little changes and addition of 3 new chunks, was been released. In August, 1999: Version1.2, adding extra chunk, was released.

Sep 232011

Among all computer graphics programs the Rater graphics is a data structure that represent usually rectangular grid of pixels, point of color and viewable via a monitor. Raster images can be stored in image files with varying file formats. A bitmap is a format that is used for storage in the display’s video memory. It is technically characterized by the height of the image in pixels by the number of bits per pixel. It can also represent a color depth which determines the number of color. In the printing industry raster graphics is also known as Contones. The word raster has been come from the Latin word. It is originally refers to the video monitors which paint the image by magnetically steering a focused electron beam. In other term it also refers to a rectangular grid of pixels. The raster graphics can scale up to an arbitrary resolution without loss of apparent quality.

Word “raster” has the origins in Latin rastrum (rake) that is been derived from the radere (scrape). It referred originally to raster scan of the cathode ray tube video monitors that paint an image by line and by magnetically steering the focused electron beam. And by association, it came to refer to the rectangular grid of the pixels. See rastrum, the device to draw the musical staff lines.

The raster graphics are the resolution dependent and they will not scale up to the arbitrary resolution with no loss of the apparent quality. The property has with capabilities of the vector graphics that very easily scale to a quality of device rendering. The raster graphics deal practically than the vector graphics with the photographs and the photo realistic images, whereas the vector graphics serve much better for typesetting and for the graphic design.