tell me about output margins

Your margin values will be deducted from the Output size you selected in the Copy tab. The effects of the margins on your copy will be displayed visually in the WYSIWYG preview window.

You can for example use margins to duplicate those of your original, crop poor quality edges or create new white edges around copied pictures for framing. Your assignment may involve following a dictated margins-standard and this option enables you to set that standard for all your copies

For many copy assignments, you will leave the four Margins settings at the value of zero because you will want to capture the whole image without cropping off any of the original's edges. With the Margins set at zero, a thin-lined frame will still outline your input and output expectations in the WYSIWYG preview.