Types of Images Clip Art – premade graphics that are available online and in many software packages; may be vector or raster. Photographs – raster images that contain millions of colors. Art Work – computer created drawings or paintings; may be raster or vector. Which type of image is appropriate? Select images that reflect the purpose and theme of the document. Use images to convey meaning and communicate, not to decorate.
The quality of an image is dependent upon two factors: 1. Resolution 2. Aspect Ratio Aspect Ratio Resolution
Image Resolution Resolution is the amount of detail (or data) stored for an image. The higher the resolution, the higher the level of detail in the image. Resolution is measured in PPI, or pixels per inch (the number of pixels contained in one inch). The higher the PPI, the more data that is stored and the better the quality. The higher the PPI, the larger the file size. Image editing software can be used to change the resolution of an image.
Image Output Methods Images can be viewed in two ways On a screen or monitor By printing it on paper Monitors The display resolution on monitors is also measured in PPI. Monitors are low resolution devices, most display 72 PPI. Printers Printers create output by placing ink or toner on paper. The resolution at which printers can print is measured in Dots Per Inch (DPI). Printers are high resolution devices in order to print images clearly without pixelation or blurriness.
Match The Image Quality To The Delivery Method. Images that will be displayed on a monitor do not need a high resolution. Using a low resolution means smaller file sizes. Images with small file sizes load quicker. Images that will be printed need a higher resolution. Images with 150 PPI are sufficient for printing on most personal desktop printers. Images with 300 PPI are better for printing on more sophisticated printers and will produce higher-quality photographs.
Aspect Ratio Aspect Ratio – relationship of an objects width to its height Aspect Ratio Resolution
Whats the answer? An image that is 1x 1 has a resolution of 100 PPI What is the effect on the resolution of enlarging the image to 2x 2? What happens to the image quality? How will this image look when printed?
Resizing a Raster Image A small image that is enlarged is easily distorted. Pixels are not added, just enlarged It is better to start with a large image and make it smaller File size will remain the same An image must be edited to reduce file size.