Megapixels: how much do you need?

There are 8 million megapixels in this little guy. /image:

There are 8 million megapixels in this little guy. /image:

You’ve got all those megapixels but still disappointed by the image quality?

Article: Arthur Ward – Technical Editor

Earlier this year, Nokia unveiled their Lumia 1020 smartphone with a whopping 41 megapixels, a figure that completely dwarfs the more popular iPhone 5 with 8 megapixels. For years, consumers always believed that bigger is better, but with recent improvements in technology most now know that this isn’t the case. If you are interested in getting a new phone and the camera is a key selling point for you, you may want to consider a few things.

More megapixels can lead to more noise in your photos. Noise is visual distortion, which can make an image look grainy or appear as speckles of discolouration in really bad cases. Camera sensors generally don’t increase in size when a newer model is released, however, modern technology allows for the pixels to be made smaller, therefore, cramming more into the same physical space.

There have been a few issues with this. Firstly, the actual size of each pixel is drastically smaller, therefore absorbing less light, which is no surprise as to why some higher megapixel cameras perform poorly in low-light conditions. Secondly, the actual area that absorbs light on a pixel, known as a photosite, is actually much smaller than the size of the pixel itself. This is because at the corner of each pixel there are a group of tiny transistors that convert the light information from the photosite into digital information that can be processed by the phone’s CPU. As these transistors do their work, they create heat. Some of which is then re-absorbed by the photosite, thus creating false readings that result in noise.

The advantage of having more megapixels is realized when you decide to crop and zoom in on a photo. Cropping a photo is essentially discarding pixels; therefore, photos that are taken with higher pixels usually look better after a crop and zoom, as there are enough remaining pixels to show the finer details. If for some reason you are interested in printing the photos you take with your phone then the megapixel count of its camera is important.

“The higher the megapixel count the more resolution the digital camera has. This means you can make bigger enlargements. As a rule of thumb, a 6-megapixel camera is sufficient up to 8×10[prints], an 8-megapixel camera is sufficient up to 16×20[prints],” according to National Geographic staff photographer, Mark Theissen. If you haven’t noticed, this means that your iPhone 5 is capable taking photos that can be enlarged and hung on your living room wall!

More megapixels, however, raise another issue. As cameras take physically larger photos, each image file contains more data, which has to be processed and stored. Nokia’s 41-megapixel behemoth captures great photos, but takes a great deal of time between shots to process them. This means you could potentially miss those awesome candids while you wait for your camera to get ready for the next shot. Also, if you intend on going for more megapixels, be sure to get enough storage space as the larger the image the more data it has to store.

Today, it is cheaper to pack more megapixels into a camera, but its more costly to have an image processor to filter out all that unwanted noise. Megapixels by themselves are not a good measure of a camera’s overall quality and other factors should be taken into consideration before you make that purchase.

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