Dots Per Inch, Pixels, Raster, Bitmap, JPEG.... if you've ever spent time inside a Kinko's, these are words that get tossed around liberally. Usually from a surly employee who throws them in your face in an effort to confuse you so they can clock out for lunch (I should know, I used to work there).
Although with the inclusion of a pretty decent camera on every smartphone, these terms have grown to become more and more commonplace. With that being said, there's still a good portion of people who haven't fully absorbed the connection between these terms and a good picture.
What it ultimately boils down to is Resolution. For the uninitiated, resolution refers to the amount of individual points of color that are contained in any given digital image. These individual points of color are referred to as Pixels, which en masse, comprise the overall appearance of your image.
What does this mean? The more pixels, the more defined and detailed your image appears. When an image contains a small amount of pixels, it appears to be "blocky" and unclear, which is referred to as Pixelation. The amount of pixels in a digital image is ascertained by it's DPI, which is an acronym for Dots Per Inch. Much like it sounds, DPI is a measurement of how many pixels are contained in each square inch of an image.
These pixel images are most commonly referred to as Raster (or Bitmap) images. There are several different formats for Raster files. The four most popular being .GIF, .PNG, .JPEG, .and TIFF. Without going off on a separate tangent, these file formats differ from each other depending on the images purpose, use, and overall appearance. The most common and widely used of these file formats is .JPEG.
So to recap, the clarity of your printed photo depends on it's resolution, which can be determined by it's DPI. But what is a good DPI value for printing? Does it matter how big the image is going to be? Lets go over the most commonly used DPI values in printing and which are best suited for large or small format. Keep in mind that all the example images have the same dimensions (1.75" x 1.75")
The lowest of the low, 75 DPI is the smallest resolution you can print with before it starts to look like your image was created with Legos. 75 DPI images cannot be enlarged without image loss, and appear be a tad "grainy" when viewed up close with the naked eye. Although in terms of large format printing (anything greater than 3ft²) 75 DPI can be advantageous in terms of file size. Also, most images printed in large format are traditionally viewed from a distance, negating most issues pertaining to image quality.
Much like the Baby Bear's bed, chair, and porridge in Goldilocks, 150 dpi is just right for large and small format. Once again, while a higher resolution is always preferred, 150 DPI works rather well with printed images, especially if it doesn't contain crazy amounts of detail. Any raster image can be enlarged by reducing it's DPI, so 150 DPI images have some wiggle room in case you want your photo to print a little bit bigger than it's original size. Just keep in mind that you do sacrifice some image quality to do so.
The universally preferred image resolution for printing, 300 DPI images print truest to the original source. 300 DPI is also the cutoff point in terms of noticeable image quality, as any difference with an image printed with a higher DPI is almost negligible. 300 DPI images print crisp and clear regardless of detail. They also allow for the image to be scaled higher than the 2 previously mentioned values. 300 DPI work best with small format printing.
In conclusion, these are more guidelines than rules. Sometimes an image might have higher sentimental value than it does resolution, but don't let that discourage you from having it transformed into a beautiful wood print. A low res image will always be offset by great emotional worth.
And if you're still confused about how your image will look when it's printed, you can always drop us a line. We're happy to help! ;)