What is High Resolution
Resolution, measured in Dots Per Inch (DPI), is a method of describing how detailed a digital image is. By saying that there are 300 Dots Per Inch in an image, we can understand that there are 300 pixels in every square inch that makes up that image. Relatively, if an image only had 100 Dots in every inch, it would be a fair bit less detailed—there would be less dots/detail in the same amount of area (One Square Inch).
At All-Tex, we insist on all artwork to be at a minimum of 150 DPI at actual final print size, this allows us to make sure your shirts are printed with great quality.
Alternatively, you might also choose to use Vector Graphics, which don't really use Resolution at all... since Vector graphics are composed of mathematically drawn shapes and lines.