How and Why to Change Resolution in Photos and Images
We receive dozens of images from customers asking if they can be enlarged. Most of these images are obtained from websites or scanned in from a magazine. 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 referring 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.
Images scanned in from magazines or newspapers are always low-resolution images. Magazines especially show evidence of this. Magazines are printed to save ink by finding the balance between what appears adequate – even very pleasing – and what can be printed at the lowest ink cost.