Image file formats

JPEG: Joint Photographic Experts Group

PROS

·      Use when you have good quality pictures      
                                                                        

·      Uses lossless compression

·      Used graphic file format

·       Used in design and photography industry

CONS
 

·      Doesn’t support transparency

·      Don’t use for logos and icons

PNG: Portable Network Graphics

PROS

·      Uses lossless compression

·      Can be used for flat areas of colours, logos, transparent or semitransparent images

·       Can be used for icons

CONS

·      Try and avoid using PNG with big photos and images with details because of the big generated file size

·      In different situations it has bigger file sizes than JPG

GIF: Graphics Interchange Format

PROS

·      There are 256 colours

·      Uses lossless compression

·      Can be used for many things including logos, flat areas of colour with well defined regions and icons with not many colours

·      Support for transparency

·       And it can be used for some animations

CONS

·      The oldest format for web – 1989
 

·       In most cases it has a bigger file size than PNG 

 BMP- Bitmap

PROS

• Bitmap files may be easily created from existing pixel data stored in an array in memory.
• Pixel values may be modified individually or as large groups by altering a palette if present.
• Bitmap files may translate well to dot-format output devices such as CRTs and printers.

CONS

• They can be very large, particularly if the image contains a large number of colors. Data compression can shrink the size of pixel, but the data must be expanded before it can be used, and this can slow down the reading and rendering process considerably.

Also, the more complex a bitmap image (large number of colors and minute detail), the less efficient the compression process will be. 


 

This image illustrates the difference between bitmap and vector images. The bitmap image is composed of a fixed set of dots, while the vector image is composed of a fixed set of shapes. In the picture, scaling the bitmap reveals the dots and scaling the vector image preserves the shapes.