Last week, The Impossible Project launched a Kickstarter campaign to fund the creation of a printer that prints images directly from your iPhone’s screen to Impossible Project film, resulting in true analog instant prints of your digital images. Instead of simply viewing images on your phone’s screen or even sending them to a lab to be printed, the Impossible Instant Lab will use the light from your phone’s screen to expose a piece of film, which then becomes a Polaroid-style photo.
A discussion on image cropping sparked up the idea to write this post after I exchanged a couple of comments in my “How to Photograph Birds” article with Tim Layton, who was concerned with cropping bird images and losing resolution for printing. He suggested to try to increase the size of cropped images with a product called Genuine Fractals 6, so that he could get to 8×10 or larger sizes. Since I have had experience with Genuine Fractals in the past and used it for some of my work, I decided to write a quick article about professionally enlarging photographs for printing, in addition to doing a comparison between the resize tool within Photoshop and Genuine Fractals 6 Pro.
1) How large can you print?
One of the most frequently asked questions by photographers who do not have much experience with the printing process is how big they can print their photographs from their DSLR cameras. Traditionally, the rule has been to divide the width of the image in pixels by 300 to get the highest quality print size in inches. For example, if you are shooting with the Nikon D90 camera, the image resolution is 4,288 (width) x 2,848 (height). This literally means that there are 4,288 horizontal pixels and 2,848 vertical pixels on the image sensor. If you multiply these numbers together, you will get to 12,212,224 pixels or 12.2 megapixels – the total number of pixels available on the sensor. So in the above case with the D90, dividing 4,288 and 2,848 by 300 gives 14.3 x 9.5 inch size prints. Why divide by 300 and what does that number mean? This number represents “DPI” (dots per inch) or “PPI” (pixels per inch), which means how many dots/pixels per inch the printer will print on paper. The more the number of “dots” per square inch, the more dense and close to each other the printed dots will be, resulting in smooth transitions and less space between those dots and therefore less “grain”. 300 dots per inch gives magazine-quality prints, while lower numbers below 150 introduce more grain and fuzziness to the printed image.