Digital images

Digital images are used in many places - icons on an application toolbar, images on websites, diagrams and illustrations placed in documents, right through to large high resolution images used to print posters.

There are two main types of image - bitmap images and vector images. In this series of articles we will look at the characteristics of computer images.

Life-cycle of an image

Computers can be used capture, edit, display, print and publish digital images.

Here is a typical life-cycle of a digital image:

Obtaining images

There are lots of ways to obtain images.

The most obvious way is to take a picture with your phone or digital camera. That will be stored on your memory card, and can later be stored on your computer disk. Digital photographs are usually stored in JPEG format.

You can also find images on the internet. You need to be aware of copyright restrictions if you are planning to publish your work, but there are plenty of websites where people post images which are in the public domain, and can be used freely.

There are many software applications which can be used to create images. Gimp is useful for painting or manipulating photographic images. Inkscape and PowerPoint are good for creating diagrams, which can be stored as vector images, or exported as image files (the image above was created using PowerPoint). Programs such as Blender can create 3D scenes and turn them into image files.

Document scanners also create image files, which are normally stored straight to disk.

Editing images

When the image is on your computer, you might edit it using imaging software such as Gimp. Gimp contains many tools, for example to crop or rotate images, adjust the colour, add a caption, or airbrush out unwanted features.

For vector images, you can use a vector image editor such as Inkscape.

Displaying images

Ultimately you are going to want to make use of your image. Typically images are added to documents or websites, or printed off as photographs. Or you can simply view the image on your monitor.

See also

• Binary
• Bits and bytes
• Units of storage
• Powers of two
• Representing numbers
• Binary numbers
• Hexadecimal numbers
• Adding binary numbers
• Negative binary numbers
• Bitwise logical operations
• Binary shift
• Character representation
• ASCII
• Extended ASCII
• Unicode
• Bitmap images
• Computer colour
• Colour depth
• Vector images
• Image file formats
• Computer sound
• Recording sound
• Playing sound
• Sound file formats