Digital cameras – Megapixels Myth

To understand the clarity of view in a picture with higher megapixels, a study was conducted which we are describing in this article. Three versions of the same photograph showing a cute baby with spiky hair in a rowboat with a 5-megapixel shot, one with 8-megapixel and one was 13. A New York graphic imaging company, whose clients include ad agencies and fashion companies, was asked to print each one at a poster like 16 by 24 inches.

The three prints were then mounted on a wall in Union Square in Manhattan. Then, passers-by were asked if they could see any difference. A small crowd gathered, and several dozen people volunteered to take the test. Only one person correctly identified which were the low, medium, and high-resolution prints. Everybody else either guessed wrong or gave up, conceding that there was no difference.

But there was also an angry group who didn’t like these methods. They took issue with the way lower-resolution images were produced by using Adobe’s Photoshop software to subtract megapixels from the 13-megapixel shot. These readers felt that “down-rezzing� a 13-megapixel photo tested only Photoshop’s pixel-subtraction techniques not camera sensors. Megapixel Myth suggests you’ll see less detail in a 5-megapixel shot than a 13-megapixel one; how it gets down to 5 megapixels shouldn’t make much difference. Fewer dots are fewer dots.

The test was repeated using more scientific methods. A professional photographer and a technical editor at Professional Photographer magazine sent an e-mail message that he’ll be happy to do the following test. Using a professional camera (the 16.7-megapixel Canon EOS-1 Ds Mark II) in his studio, he would take three photos of the same subject, zooming out each time. Then, by cropping out the background until the subject filled the same amount of the frame in each shot, he would wind up with nearly identical photos at three different resolutions: 7 megapixels, 10 and 16.7.

Instead of a smooth-skinned baby, Vener’s model was positively bristling with detail: curly hair, textured clothing, a vividly patterned background and a spectacular multicolored tattoo on a hairy arm. The new 16-by-24-inch enlargements were set up on identical easels at a public library. Clipboard in hand, the test was conducted again.

The results were the same. This time, out of about 50 test subjects, only three could say which photo was which. So is the lesson, “Megapixels don’t matter?� Not exactly. First of all, having some extra megapixels can be extremely useful in one important situation: cropping. You can crop out unwanted background and still have enough pixels left for a decent print.

Of course, it’s better to get your composition right when you take the photo, but this is still a great trick to fall back on. Megapixels may matter to professionals, too, especially those who produce photos for wall-size retail displays. And even in consumer cameras, there are certainly limits to the irrelevance of megapixels.

The actual lesson, then, is for the non-professional, five or six megapixels is plenty, even if you intend to make poster-size prints.

Unfortunately, blowing up the Megapixel Myth also takes away a convenient crutch for millions of camera shoppers. If you’re torn between two camera models, you now know that you shouldn’t use the megapixel rating as a handy one-digit comparison score.