File Format, Compression Techniques, Image Resolution and Colour Depth (M3)

I am now going to describe JPEG files and zip files

JPEG (Joint Pictures Expert Group) is a file format that is used to compress photographic images. JPEG is one of the most popular image format used by digital cameras and such. And is also popular with storing and transmitting images on the internet.

Zip files are single files it is most commonly used on windows operating systems. Zipping is the act of packaging a set of files into a single file or archive that is called a zip file. Usually, the files in a zip file are compressed so that they take up less space in storage or takes less time to send to someone. There are different tools used for zipping files for different operating systems for windows there are WinZip and Netzip, MacZip for Macintosh users and Zip and UnZip for UNIX systems. Have you have received a zip file, you may have to extract and decompress the file by using the same kind of tool that was used to zip the original file.

Image resolution
Image resolution describes the detail an image holds. The higher the resolution, the higher the detail in the image. Resolution determines how close lines can be to each other and still be visually resolved. Images are made up of lots of different colour pixels and if you zoom in to the picture you begin to see the pixels that are making up the picture. If you colour in individual pixels to make the quality better. Making the images bigger or smaller can also affect the quality of an image and this is the problem with manipulation of images.

I am now going to demonstrate the impact of zooming in on a image can have to the quality and file size of the image.

The file size of this image is 41.5 KB (42,553 bytes)

And the file size of this is 122 KB (125,201 bytes)

As you can see the further I zoom in on the image the worse the quality becomes and the file size becomes larger.

Colour depth
The number of possible colours in a graphic image, stored as a given number of bits per pixel. A colour depth of 8 bits provides 256 colours; 16 bits (also known as "High Colour") provides about 65,000 colours; 24 bits (also known as "True Colour") provides about 16,000,000 colours. The higher the colour depth gives a broader range of distinct colours.