Resolution

Resolution measures how many pixels are packed into each inch of output — dots per inch, or DPI — and only means something in relation to a physical size. A file that's 1500 x 1500 pixels prints at 300 DPI at 5 inches wide, but stretch it to 15 inches and it drops to 100 DPI, a third as sharp, with the exact same pixels doing three times the work. Screens only display around 72 to 100 pixels per inch, which is why web graphics look sharp on a monitor at a fraction of the pixel count print needs.

This is the single biggest gap between what a buyer sees and what a press operator sees. A logo pulled off a company website looks perfect in an email attachment because it's viewed at screen resolution, at screen size — scaled up to fill an 11-inch chest panel on a DTG tee, the math changes and so does the sharpness. We check every incoming logo at actual print dimensions before it reaches the art department, because "it looked fine on my phone" isn't a spec.

Screen printing and embroidery both tolerate lower resolution than digital methods, since a screen reduces detail to solid ink layers and stitches don't render pixels at all, so 150 DPI can be fine for a simple one-color design headed to a screen. DTG and sublimation reproduce photographic detail directly, so those jobs want the full 300 DPI at final size, no exceptions.

Buyers commonly assume resolution is baked permanently into a file rather than tied to how big it's being printed. The fix for low resolution isn't a "sharpen" filter — it's sourcing a larger original or, for logos and flat art, having it vectorized so size stops being a resolution problem at all.