DPI is actually a printing term. It refers to how many dots per inch a printer can print. In reality, the images you have on your screen are pixel based. So you need to make sure that your Pixels Per Inch (PPI) are high enough to print . PPI is how digital images are represented. The higher PPI the smoother and less grainy and image will be.
Most images on the web are saved at 72 PPI so that they can be downloaded quickly. They will look great on your screen but when you go to print them, not so much. In oder for your buttons to print well you need to make sure that they are as large as the button you intend to make, and be saved at 300 PPI. For instance, if you are creating a 3” button, but your image is on 2” but had 300PPI, the image will have to be stretched to fit your button, which will result in your image being distorted. 300 DPI/PPI is by no means the maximum that we can print at. Our digital press can print up to 2400 x 2400 PPI.