A megapixel is one million pixels. It is commonly used to describe the resolution of digital cameras. For example, a 7.2 megapixel camera is capable of capturing roughly 7,200,000 pixels. The higher the megapixel number, the more detail the camera can capture.
Rough Idea
Like calories, megapixels are a measure of quantity, not quality. You need a certain number of megapixels depending on the way to want to share a photo. But just as the number of calories in a meal doesn't say much about how nutritious it is, the number of pixels in a camera doesn't say much about the quality of the image they can capture.
Does Image quality depend on MegaPixel count?
Quality is a complex issue based upon a camera’s optics, image sensor design, firmware, engineering, and yes, its pixels — but not its megapixel count. At the heart of your camera is the image sensor, which contains the array of pixels. These pixels are like buckets that collect photons (i.e., light).
Image sensors come in different sizes. The larger the image sensor, the larger the pixels can be, and the more photons each can collect. The result is a picture that is cleaner, with less image noise (graininess), and typically a finer differentiation and delineation of highlights and shadows.
How to determine sensor size physically? and its relation with MegaPixel
To get a rough idea of any camera’s sensor size, look at the diameter of the lens. An 8-megapixel smartphone camera packs 8 million pixels onto a minuscule sensor about the size of a baby aspirin tablet. However, an 8-megapixel compact camera has a significantly larger sensor, about the size of a pinky fingernail, so each individual bucket (pixel) is bigger and deeper. That allows it to capture more light without the light spilling over to adjacent pixels — which is a prime cause of noise (a grainy appearance) and ghosting (a double image).
Advanced compacts, mirrorless cameras and semipro and professional DSLRs come equipped with even larger sensors ranging in size from a postage stamp (known as APS) to a comparatively huge "full-frame" sensor of about 1.5 by 1 inches found in top-of-the-line DSLRs. So, all other things being equal, an 8-megapixel DSLR will produce far better images than an 8-megapixel compact camera, just like the 8-megapixel compact will capture better images than your 8-megapixel smartphone.
Where MegaPixel do matter?
Where megapixels do matter is the size you want your final picture to be. You need to have a camera or smartphone whose megapixel count matches how you plan to use your photographs. This is particularly important if you plan to print your pictures, because print quality is very dependent upon having enough data (pixels) to define the picture.
Disadvantage of having higher MegaPixel
Having more pixels than you really need can actually hurt image quality. That’s because when you upload an overly large picture to social media, output it to a printer or send it to a photo book producer, your image will be downsized automatically. In other words, the software or upload process will randomly delete pixels without the smarts to understand what might be critical in the picture, such as the sparkle in a child’s eye or the razor-sharp edge of a leaf.
Photos with too many megapixels also take much longer to upload and might even fail partway through. And if you're uploading on the go, you're eating into your wireless data cap more than you need to.
How to calculate Megapixel needed for specific Image size?
Step1)Determine the physical size of your print, such as 4 x 6 inches, 8 x 10 inches, etc. Then, multiply the width by 300, and the height by 300, which will give you the size in terms of pixels. (300 ppi — pixels per inch — is recommended for good-quality prints.) Therefore, an 8 x 10 inch print would be 2,400 x 3,000 pixels.
Step2)Multiply the width (in pixels) by the height (in pixels). So for that 8 x 10 inch print, it would be 2400 x 3000, which equals 7.2 million pixels.
Step3)Divide the result from step 2 by 1 million, and you have the number of megapixels you need to make a good print. In this case, the minimum resolution you’ll want your camera to have is 7.2 megapixels.
Source of research:- Google.
I hope that now all your doubts on MegaPixel is sorted out.
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