Image Resolution

A raster image is an array of individual bits or pixels (picture elements) arranged on a grid. These files are resolution dependent (their quality is determined at the time of creation) and have an absolute resolution (you can’t add more quality once you have the image). This quality is expressed in terms of PPI (pixels per inch)—simply the amount of detail originally captured and saved on disk.

Ok so now that we know what a files resolution is all about, how much do we need? Good question! Unfortunately, we have to answer it with a question. How will you reproduce this image?

The required PPI for a quality image is directly related to the images use. This is because PPI is used to take advantage of a devices resolution. Depending on the type of output you intend for your image (inkjet, high-end half tone or line art prints, web or multimedia) the effective resolution required will change. If you don’t believe me, try it yourself!

Any image with effective resolution for web use will look coarse or pixilated on a high-end printer, while an image with effective resolution for the high-end printer will display on a web page in about the same amount of time it would take you to run down to the coffee shop for a nice hot cup of java.

Some are of the mind that you should always capture the greatest amount of PPI that you are capable of and leave it at that. Now, I will agree with this only if you do not know the type of output your image requires. The most effective workflow will involve understanding your goals and acquiring the correct resolution from the get-go.

This entry was posted on Tuesday, January 3rd, 2006 at 1:44 am and is filed under Design. You can follow any responses to this entry through the RSS 2.0 feed.

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