I have an image of Wang Ximeng's A Thousand Li Of Rivers And Mountains which currently resides in the forbidden palace in Beijing. I fell in love with this painting and searched high and low for a suitable image which i could digitally sample and which i have painstakingly restored with Photoshop to clean it up and get it to a point where i could print it at a reasonable size. The original picture sampled is 39974 × 1600 pixels can you tell me what the largest image it could be printed at without loosing definition or becoming pixilated Also a further question is, will i be infringing any copyright laws if i was to get a large scale print of the said image either for personal or resale purposes. Thanks
Ryan is correct about enlargements. All enlargements will lose quality but one common way to enlarge a print is using the "Photoshop enlarge 10% trick". There are also proprietary enlarge photo software out there like Perfect Resize by OnOne or like Scott has said, Photoshop has increased their enlargement algorithms.
For the size you want to print is up to you. Based on your resolution I would suggest printing at around 8" high at around 200ppi for an ok picture quality. You will either need to find a custom frame or crop the image to fit a standard sizes of 2:1 to 3:1.
Determining the optimal output size for a given image is a simple process. First, determine the optimal output resolution. If you don't know it, your vendor or key op should be able to help you out. As a rule of thumb, 300ppi is the standard for magazine-level printing, while large format printing tends to be 150ppi (in my experience). Once you know the desired output resolution, you simply divide each of the image's dimensions by that number. For example, your image is 39,974 x 1600, so:
39,974 / 150 = 266.493" wide.
1600 / 150 = 10.667" tall.
Therefore, the optimal output size at 150ppi is 266.493" x 10.667".
Keep in mind that "ppi" and "dpi" are very different measurements. "Pixels per inch" (ppi) is the measure of pixels in one inch and is a purely digital concept that represents the concentration of detail sent to the printer. "Dots per inch" (dpi) is the number of dots the printer lays down on the media. This is usually hard wired into the printer and cannot be altered. A printer's dpi dictates the maximum amount of detail that it is capable of producing. Different printers have different dpi ratings, but no matter how much ppi you have, it can never exceed the printer's dpi when printed due to the physical limitations of the output device.