GRAPHIC DESIGN

TOPIC – RASTER IMAGE FORMATS

NOTE - RASTER IMAGE FORMATS

DIFFERENT FORMATS

An image format is simply a way of storing the information in the image as a series of zeros and ones. Because images can easily contain millions of zeros and ones, we have developed different formats that reduce the amount of space required to store images.

FILE COMPRESSION

The idea of reducing a file’s size is called file compression.

The advantages of reducing image sizes include requiring less storage space for images and faster internet web browsing (as the images will transfer more quickly).

FILE FORMAT

The format of an image is its file extension. So the file named bird.jpg is a JPG image file. On the other hand, the file named wave.gif is a GIF file.

COMMON FORMATS

The most popular raster image formats today are JPG, PNG and GIF.

Other formats include BMP and TIF. Google has developed the WEBP raster image format that has been slowly gaining traction on the internet.

LOSSY VS LOSSLESS

Some formats, in order to reduce file sizes, will actually alter the original image. Such formats are called lossy. On the other hand, format that do not alter the quality of the image when saving it are called lossless.

COMPARISION OF FORMATS

The BMP format is the most basic format. It is not used very much because there is always a better format available that will take less storage space.

BMP	JPG	GIF	PNG
Pronounced “bitmap”	Pronounced “J-peg”	Pronounced “jiff”	Pronounced “P” “N” “G”
No colour limit	No colour limit	Max of 256 colours	No colour limit
No file compression	Excellent compression	Excellent compression	Some compression
Lossless	Lossy	Lossless	Lossless
Good for any type of image	Good for photos	Good for cartoons	Good for any type of image.
No animation	No animation	Animation support	No animation
No transparency	No transparency	Transparency support	Transparency support

When to use BMP?

• Never. The PNG is always a better option.
  
  

When to use JPG?

• A JPG is excellent for photos. However, it is not suitable for cartoon images such as logos because little “artifacts” are left in the image.  JPEG provides a very small drop in quality (often impossible to see) in exchange for a big drop in file size. 
  
  

When to use GIF?

• GIF is now only useful for animations. I could be used for cartoon images as well but it is limited to 256 colours. So PNG is often a better choice for still images.

When to use PNG?

• The PNG format is ideal for any cartoon image. It can also be used for photos that you plan on saving many times as you edit them. 

QUESTIONS

1) Which format should be used to store a photo?

2) Which format should be used to store a logo?

3) Which format must you use to create a simple image animation?

4) Which format is lossy?

5) Which format should you use if you cannot remember which one to use?

SOLUTIONS WILL BE SHARED