Past Tense

Digital photos can be viewed on computer screens or printed on paper. Most of the time you are most likely to print on standard paper sizes like 4X6 or 5X7. Every now and then however you might want to make enlargements of some photos that you specially care about. Print enlargements quality depends on your digital camera mega pixels figure, here is how.

There is a certain resolution referred to as number of pixels in each digital photo that you take. Pixels can be represented by one number or sometimes as two numbers depicting the number of pixels over the X axis and the number of the Y axis (multiply these two numbers together to determine the total number of pixels in the digital photo).

You are printing these digital pixels onto paper each time you print a digital photo. If the paper size is big relative to the photo resolution, the quality of the print will be poor. Poor quality is often seen by pixelization or the ability to actually see the individual pixels on the print.

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 assessment of what comprises 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.

The following qualities are usually linked with a specific PPI number:

PPI 100 - fair to bad

PPI 200 - good

PPI 300 and up - very good

The next rational step would be to determine how many mega pixels are needed for good quality printing on a particular paper size. Don’t worry, 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):

page 4X6 0.24MP 1MP 2MP

5X7 0.35MP 1.5MP 3MP

page 8X10 0.8MP 3MP 7MP

page 11X14 1.5MP 6MP 14MP

16X20 3MP 12MP 28MP

20X30 6MP 24MP 54MP

This table is just an estimation of what is considered suitable number of mega pixels for different paper sizes. There are many other factors to consider when making enlargements. Experimenting with different paper sizes is the best way to go but it can be expensive. In addition sometimes what is considered poor quality pixelization can actually be a nice artistic effect which strengthen the unfortunate fact that in addition to the above calculation some common sense and experience are needed in order to match a specific digital photo to a specific paper size enlargement.