D2

1) File Format

GIF

JPEG

2) Compression
The compression of an image is used to minimize the size of an image file without losing the quality of an image to an unacceptable level. Image compression reduces the amount of time required for images to be sent over via the internet which allows users to navigate at a quicker rate. The compression of an image is usually determined by 5 different options and they are; low, medium, high, very high and maximum. The compression of an image can be changed when an image is used on a website/email so that the image doesn't take a large amount of time when loading the webpage/email. Image compression is normally most suited for a JPEG image as it is a format for compressed image files.

JPEG

3) Colour Depth
The colour depth is used to indicate the different colours used in a single pixel in an image. When chaning the colour depth of an image, the file size will change according to how good or how bad the quality of the image is. The colour depth is normally measured by the amount of colours used in an image  and they can range from 2 to 256, although the ones shown below are 8, 32 and 256. The colour depth of an image can be changed so that it can be loaded easily onto the internet quicker and more efficiently. Colour depth is most suited for a graphics interchange format or a GIF image as they are more compressed to reduce the amount of time used to transfer the image.

GIF

4) Resolution
The resolution of an image is determined by the number of pixels in an image and is normally measured by pixels per inch (ppi), dots per inch (dpi) or megapixels (MP). The more pixels used in a image, the more quality the image will have although this also means that the image will have a larger file size which will take longer to load on websites/emails via the internet. If the resolution of a smaller image is changed from a smaller resolution to a higher resolution, there may be some quality loss as there are not enough pixels in the original image which creates a blurry effect. For example below you can see that when an image with a web resolution of 72 ppi is changed to a print resolution of 300 ppi, the image appears much larger and loses some of its quality as the resolution has been made a lot bigger. The resolution of an image is normally changed when someone wants to lower the file size to allow the image to be put onto a website/email or when someone wants to print off an image via a printer.

Web Resolution - 72 ppi

Print Resolution - 300 ppi