Dpi & ppi are the problem. What Commercial printer refers to DPI? I think You must be refering to LPI "lines per Inch". Laser printers, imagesetters, printing press, thermal wax printers, ect., all use halftones to simulate shades of grey! Ink jet printers use dpi because they dont use halftones and instead use groupings of the same sized dot to simulate shades of grey. Commercial printers don't use dpi or only refer to it because it's old equipment. Besides if you dont understand dpi, lpi & ppi, your going to have a big problem. Try resizing you image to 1500 dpi as Boxx saids and you had better have one hell of a computer cause the file size will be ridiculous. The only type of art that uses A high level of Dpi is in the scanning process and only when your scanning in Line-ART. How do I know all of this you ask, because it took me almost 2 yrs of self studying and passing Adobe's Expert level Certification test. But please, don't take my word for it, if you look it up in your photoshop manual it will tell you the same thing. Further more, high end magazines and high quality brochures use a LPI of 150, wich means your image/project should be using a base of 300 PPI. If your image was going to be used on a 1200 dpi laser printer, your image would need to be set to 400 PPI.