A computer display is made up of small squares, called pixels. Digital images are also made up of pixels and have a resolution (measured in pixels) indicating the width and height. The higher the resolution, the larger the image appears on the screen. As the resolution increases, so does the file size (in bytes) because the image contains more information.

The display has a screen resolution, measured in pixels, indicating the width and height: e.g. 1024 x 768 pixels denotes a display consisting of 1024 rows of 768 pixels. Displays are often capable of using different screen resolutions: e.g. 800 x 600 pixels or 1024 x 768 pixels, 1280 x 1024. The higher the resolution, the more detail is displayed on the screen.

At a screen resolution of 1280 x 1024 pixels, a 518 x 255 image appears quite small on the screen. At a screen resolution of 800 x 600 pixels, the image appears much larger. The image's actual size has not been altered, it simply takes up more of the screen pixels, as there are less screen pixels available. 1280 x 1024 800 x 600

Compression File formats are used to encode digital images. Part of the reason for different file types is the need for compression. Image files can be quite large, and larger file types mean more disk usage and slower downloads. Compression is a term used to describe ways of cutting the size of the file. This can be achieved by removing colour information (e.g. From 16 million colours to 256) or by removing detail that would be unnoticeable to the eye. Compression schemes can be described as lossy or lossless. This indicates whether compression affects the quality of the image on successive saves.

Digital Images: Output Choice of image format depends on the type of output. If you are using images for publications, desktop publishing or a final print output, choose lossless formats and high resolutions (larger file sizes) For the internet, speed and accessibility are the most important aspects, so formats which give a decent image but have a relatively low file size are ideal. Therefore, we might use ‘lossy’ formats like JPEG.

JPEG (Joint Picture Experts Group) WEB PRODUCTION FORMATS JPEG (Joint Picture Experts Group) JPEG is popular image format for web use due to its retention of image quality with relatively small file sizes. Beneficial effects of compression are best seen on photographs with smooth gradations of colour. JPEG is the most commonly used format for saving Digital Photographs. JPEG is a ‘lossy’ format. Not as effective for line drawing, text objects or icons where contrasts are sharp.

GIF (GRAPHIC INTERCHANGE FORMAT) WEB PRODUCTION FORMATS GIF (GRAPHIC INTERCHANGE FORMAT) GIFs are used to display limited (indexed) colour graphics on the web. More appropriate for logos and artwork than photographs. GIF files support transparency. GIF is a compressed format that reduces the file size of images. It only supports a limited number of colours.

PNG (Portable Network Graphics) WEB PRODUCTION FORMATS PNG (Portable Network Graphics) PNG was developed as an alternative to GIF for displaying images on the web. It uses lossless compression and supports transparency. Some browsers do not support PNG.

TIFF (TAGGED IMAGE FILE FORMAT) PRINT PRODUCTION FORMATS TIFF (TAGGED IMAGE FILE FORMAT) TIFF is a common bitmap image format, so most image-editing software and page-layout applications support TIFF images up to 2GB in size. TIFF supports most colour modes and can save images with alpha channels. While Photoshop can also include layers in a TIFF file, most other Applications cannot use these extended features and see only the Flattened image.

SOURCING IMAGES From the Internet From a Digital Camera

SOURCING IMAGES From the Internet USING SEARCH ENGINES VIDEO HERE

SOURCING IMAGES From a Digital Camera TAKING PICTURES AND TRANSFERRING THEM TO A PC VIDEO HERE

PREVIEWING IMAGES Viewing and Organising Digital Images with Windows