How does the image editor handle size and the print area?
The editor builds its document from the product position's print area and displays the dimensions in millimetres. Its working resolution is 300 dpi. The dashed print-area boundary is the useful guide for what can print on that position.
If any part of the visible artwork extends outside the print area, that part is clipped when you save. If the artwork is entirely outside the print area, the editor tells you that nothing would print and will not save an empty result. The save confirmation shows the approximate printed width and height of the painted content.
Saving trims transparent or unpainted edges and uses the trimmed content size for the design size. Existing placement adjustments are kept. If the same design is used on more than one product position, the size is shared and the editor works to the smallest applicable print area. A save can therefore reduce the requested size to the maximum allowed for the positions that use the design.
Use Move, the size fields and Centre in print area to make the artwork fit. Always read the save message and check the refreshed quote preview after saving.
The editor working at 300 dpi does not add missing detail to a small original. See the low-resolution warning if the image looks soft.