When To Go BIG!

By: David Peters

With all of the advances in digital technology, digital photo can now be viewed almost anywhere through any medium. Most of the time however, you are going to want to print out your photos, typically on standard paper sizes like 4X6 or 5X7. But what should you do if you have that special photo that you want to make an enlargement of? Print enlargement quality is based on your digital camera mega pixels figure. Let's look at how

Every digital photo that you take with your camera has a certain resolution normally expressed as the number of pixels in the photo or sometimes as two numbers depicting the number of pixels over the X axis and the number of the Y axis (multiplying these two numbers provides the total number of pixels in the digital photo).

You are actually printing these digital pixels on paper when you print your digital photos. If the paper size is big and the resolution is large, the digital print quality will be poor. The end result can be the ability to actually see the individual pixels on the print. This is known as pixelization.

So how can you determine what is the maximum print enlargement that you can make from a certain digital photo? There is no one precise answer. In addition to the actual number of pixels in the photo there are other things that can influence the answer like how many details are in the photo, what were the lighting conditions and more. Even when considering the number of pixels the answer is not precise since different people would have different views about the quality of a photo print.

A rough guess of what consists of a good print quality is based on the pixels density or in other words the number of pixels per inch on the printed photo. This is also known as PPI (pixels per inch) and it represents the number of pixels over an axis line.

Experiments show that the following qualities are usually associated with a specific PPI number:

PPI 100 - fair to bad

PPI 200 - good

PPI 300 and up - very good

The next reasonable step would be to determine how many mega pixels are needed for good quality printing on a specific paper size. Calculating this number is very easy. All you need to do is to simply multiply the page length by its width in inches, resulting in the number of square inches on the page. Now multiply this number by the square of the PPI number and the result is the number of pixels on the page which is the number of pixels we want our source photo to have. Here are the numbers calculated for some common sizes (for 100,200 and 300 PPI respectively):

4X6 0.24MP 1MP 2MP

page 5X7 0.35MP 1.5MP 3MP

page 8X10 0.8MP 3MP 7MP

page 11X14 1.5MP 6MP 14MP

page 16X20 3MP 12MP 28MP

page 20X30 6MP 24MP 54MP

This table is just an estimation of what is considered a fitting number of mega pixels for different paper sizes. When making enlargements, there are many other factors to consider. Try experimenting with different paper sizes, but be careful as this can get expensive. And remember that there are always exceptions to the rules. Sometimes what is considered poor quality pixelization can actually result in a nice artistic effect in your enlargement. What it comes down to is that while the above calculation helps, common sense and experience are needed to match a particular digital photo to its best possible enlargement size.