Introduction To Raster Image

Introduction to Raster Images

There are basically 2 types of Images 1.Raster images & 2.Vector images. Vector images are based on mathematical objects such as lines and curves.

But what is a Raster image? It is a type of image made up of small rectangular pieces which are known as pixels. Pixel is a small part of an image i.e. an image is made by combining lots of pixels. That image is known as Raster Image. This Raster image is also known as bitmap images.

Raster images are dependent on the resolution that’s the reason that they have large size. The image becomes pixilated when the zoom level is increased. As Raster image is dependent on resolutions. Due to this some images can be rescaled, while other images are not seen clearly. In Raster image is measured in ppi (pixels per inch).

The color system used in Raster images is RGB (Red, Green, and Blue). The pixels usually smooth out visually for the user, who sees a photograph or drawing, when a Raster image is viewed.

The Formats of Raster Images

• .tiff (tagged image file format)

It is tag based file format which promotes the interchange of digital photographs and line arts. Mostly Image Manipulation applications, page layout & publishing applications, faxing, scanning, word processing and other applications are supported by tiff. It is an image compression format. This format is developed by Aldus (Adobe Systems). The main purpose of this format is to create such an environment that the image data can Up till now 4 revisions are developed of .tiff

• Revision 3.0 which is in HTML.

This memorandum is mainly developed by Aldus now known as Adobe in the year 1986.

• Revision 4.0 which is in HTML.

This memorandum is developed on 31 April, 1987 by Tim Davenport of Aldus and Manny Vellon of Microsoft in conjunction. This revision was developed with minor enhancements.

• Revision 5.0 which is also in HTML.

This Technical memorandum of Aldus and Microsoft was developed on 8/8/88. The basic new thing about this revision was the LZW compression, support for Palette Color images.

• Revision 6.0 which is in PDF

This memorandum was developed by Adobe Developers Associations previously known as Aldus in March 1995.

• .gif (graphic interchange format)

Gif is like short animation. In 1987 CompuServe developed this format. CompuServe developed this format to give some moving effect or animation to a still image.

• . png (portable network graphics)

To improve the gif and to replace it .png was developed. It was developed by PNG Development Group in 1996

• . jpeg (joint photographic experts group)

To compress the photographic images this file format is used. By this format we can adjust the storage size and image quality.

• .bmp (bitmap image)

Bmp file format is very simple format and familiar to windows. Generally bitmap files are stored in Device Independent Bitmap (DIB) format, due to this format windows allow  display of bitmap image to any display device.