WHAT ARE HIGH RESOLUTION PICTURES?

We receive dozens of images from customers asking if they can be enlarged. Most of these digital photos are obtained from websites or scanned. Images need to be at least 200 dpi (dots-per-inch) for purposes of enlargement, and 300+ dpi is even more recommended. On a computer screen this is really ppi or pixels-per-inch. DPI or dots-per-inch technically relates to a printed picture. Most people just say dpi when refering to either situation.

Digital images can appear beautiful to the eye and still be very "lossy" in their actual content. "Lossy" means that the image is saved in a format that is stripped of a major amount of content. The popular JPG and GIF image formats are known as "lossy" formats because it is easy to decrease the substance of images down to the smallest possible size that still "appears" satisfactory. Images in these formats can appear substantially attractive to the human eye and still have a lot of their image information stripped out of them. This is done so that their file size is smaller and they load on web pages quickly.

Original Image - Scanned at 600 dpi

Images scanned in from magazines or newspapers are also low resolution images. They were printed to save ink yet still appear adequate - even very pleasing. Take a look at the image at the right. This appeared to be an image that we could enlarge big enough to build a floor-to-ceiling wall mural with YottaPrint. We scanned it from a magazine advertisement using a new scanner at 600 dots-per-inch, a resolution so high that it made the file size very large.

When this original is enlarged, the lossiness of the original is evident. Since the original was a low resolution image, there simply was not enough information in the photo to enlarge it satisfactorily. See the two examples below. You can clearly see what the human eye missed:  dots in the original that are not visible until the image is enlarged.