What Is a Megapixel?

Why do pixels matter anyway?

A megapixel, often shortened to MP, is equal to 1 million pixels. A pixel is an individual element of a digital image. The number of megapixels determines the resolution of an image, and a digital image with more megapixels has more resolution.

A higher resolution is certainly desirable in a digital photograph, as it means the camera uses more pixels to create the image, which should allow for greater accuracy or fidelity.

The Technical Aspects of Megapixels

On a digital camera, the image sensor records the photograph. An image sensor is a computer chip that measures the amount of light that travels through the lens and strikes the chip.

The image sensors contain tiny receptors, which are called pixels. Each of these receptors can measure the light that strikes the chip, registering the intensity of the light. An image sensor contains millions of these receptors, and the number of receptors (or pixels) determines the number of megapixels that the camera can record, also referred to as the resolution.

Avoiding MP Confusion

This is where things get a little tricky. While it stands to reason that a camera with 30 megapixels should yield better image quality than a camera that records 20 megapixels, it's not always the case. The physical size of the image sensor plays a more significant role in determining the image quality of a particular camera.

Think of it this way: A larger image sensor in physical size that contains 20 MP will have larger individual light receptors on it, while a small image sensor in physical size that contains 30 MP will have very small individual light receptors.

A larger light receptor, or pixel, will be able to more accurately measure the light entering the lens than a smaller light receptor. Because of the inaccuracies in measuring light with a small pixel, you end up with more errors in measurements, resulting in "noise" in the image. Noise are pixels that don't appear to be the correct color in the photograph.

When the individual pixels are closer together, as they are with a small image sensor, it's possible that the electrical signals that the pixels generate could interfere with each other, causing errors in the measurement of the light.

So while the number of megapixels a camera can record does play a role in image quality, the physical size of the image sensor plays a larger role. For example, the Nikon D810 has 36 megapixels of resolution, but also offers a very large image sensor, so it has the best of both worlds.

Changing the MP Settings

Most digital cameras give you the option of changing the number of megapixels that are recorded in a photo. So if the camera's maximum resolution is 20 MP, you may be able to record images that are 12 MP, 8 MP, 6 MP, or 0.3 MP.

While it's generally not recommended to record photos with fewer megapixels, if you want to ensure a digital photo that will require a limited amount of storage space, shoot at a lower megapixel setting, as recording with a larger number of megapixels or at a larger resolution requires more storage space.

  • How many megapixels is 1080p?

    1080p is approximately 2 megapixels. Technically, 1080p is more like 2.1 megapixels, but cameras aren't usually developed and sold with fractions of a megapixel. Most cameras today have many more than 2 megapixels.

  • What's a good number of megapixels?

    For the average consumer, up to 10 megapixels will often be enough to take high-quality pictures. If you're looking for a professional-grade camera, you'll generally want 20 megapixels or more depending on what kind of images you're taking.

  • How many megapixels is 4K?

    If you see a 4K label on a camera, it means the camera can record images at about 12 megapixels. This also means it can record video equal to double the resolution of a standard HD TV (1920 x 1080).

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