Raster Images and File types

pixel

"picture element". Raster images and raster displays are made of these.

.GIF

this image format offers transparency but a low number of colours and lossy compression.

.JPEG

this image format supports a high number of colours but with lossy compression and no transparency.

.PNG

this image format supports a high number of colours with lossless compression and transparency.

.PSD

this is a a propriatory image format owned by Adobe and used by Photoshop.

Microsoft Paint and Adobe Photoshop

two graphics packages used to create bitmap images.

pixelation at high zoom

a disadvantage of raster image types.

lossy

a form of compression that results in image detail being lost .

high detail and low file size

an advantage of raster image types.

bitmap

an alternative name for a raster image.

digital camera or scanner

hardware devices used to capture a bitmap image.

colour depth

refers to the amount of memory bits allocated to storage of colour information in the image file.

resolution

the width and height in pixels of a raster image or display.