Online Versus Print

Managing Graphics and Images

An in-depth study of graphic formats is found under The Perfect Page heading. Knowing about the wide variety of formats and about the difference between raster and vector images is very important and is covered in that section.

Another side to the study or graphics and images is the whole question of resolution especially as it exists in the digital world.

In the old world of print, images were produced by enlarging negatives or transparencies captured with film. Printed images were broken into tiny dots, printed on paper. Those individual dots represented the color or intensity of the that particular part of the image. Breaking images into dots relies upon the inability of the human eye to see the individual dots, but instead to merge the dots together and recreate the image itself in the brain. The eye does not discriminate between the does at a resolution of about 200 dots per inch. When an image is composed of dots that are so small that more than 200 fit into a square inch, they make the brain think that the image is a continuous tone. Photos and images are typically printed from dots of ink at resolutions ranging from 120 to 300 dots per inch.

The same principle holds true in the digital age. Onscreen, however, people talk about pixels per inch rather than dots. Image quality still depends upon having enough image information so that each inch of the image can fool the eye into seeing continuous tone. It is probably true that the eye is fool more easily by the pixels on a monitor than by dots on a printed page.