DPI and Image Quality

Have you ever made a map or graph and been disappointed with the image quality or resolution? It happens to all of us, so today I’m sharing two quick tips for what to check the next time this happens.

Low image resolution happens more frequently with large graphics, since some software programs have a default number of pixels they use in an image, regardless of the image size. If you’re working on a larger image than usual, this makes the density of pixels (called Dots Per Inch or DPI) lower.

What’s a good DPI to aim for? It depends on the level of detail in your graphic and what you’ll be using it for. Anything higher than 300 is usually fine, but for maps I might want to stretch to fit a poster I usually use 500-700. After you make the graphic, check it in your photo viewing software at 100% and 200% zoom. If it’s crisp and readable at both, your DPI is high enough.

Now here’s where I always get concerned. You embed your gorgeous high-res image in a Word doc and it looks fuzzy. This happens because Word automatically compresses files when you embed them. For me, I’m usually embedding images in a manuscript that will be typeset by someone else. I put the images roughly where they belong in the text, but when I send off the manuscript I also include the image files separately. In this case, it really doesn’t matter that the embedded images aren’t crisp. But, there is hope if you’re planning on printing straight from Word or otherwise need the images to be nice– just turn off image compression by following the directions here on Microsoft Support! Now you, too have the skills and know the lingo to make your images high resolution.