Megapixels are not always the ultimate measure of camera quality, as many manufacturers and marketing types claim, even at the most extreme extremes. In fact, as counterintuitive as it may seem, too many megapixels can actually be a hindrance, leading to large file sizes, slow transfers, and less space on your device for other media. This is especially true at the consumer level, where phones have eliminated the need for a cost-effective digital camera, and most photos taken with them are not intended to be the centerpiece of a magazine article or to capture a subject in fine microscopic detail.
There are also cases where a higher number of megapixels can actually lead to lower final image quality. This is especially true if you are exporting an image to another device, such as a printer or website. Many of these destination outputs will automatically resize an image. Depending on the intelligence of the downsizing algorithm, key pixels may be truncated when overabundant, resulting in loss of detail.
How many megapixels do you need?
First, think about what a megapixel actually is and what it means for your image. A megapixel is an indication of the resolution of a digital camera sensor or image, with each megapixel equivalent to 1 million individual pixels (pixels being the tiny dots of color that together make up a digital image). If your camera takes photos that are 4,000 pixels wide and 3,000 pixels high, for example, it produces 12 megapixel images (12,000,000 pixels).
The calculation is important because the number of megapixels can be somewhat misleading. Let’s say you double the number from 50 megapixels to 100 megapixels in an image. The reality is that you are only doubling the width or height, or only increasing both by 50% – you are not actually doubling the total size of your image. The other important thing to remember is that megapixels are purely a representation of the resolution of an image, the number of pixels it is constructed from. Although resolution is important for fine visual clarity, it is only one of many variables that contribute to the actual quality of an image.
Other key factors in image quality
I don’t want to completely dismiss the importance of resolution (and by extension, megapixel count) for image quality. More pixels means finer textures, edges, and small features. For example, strands of hair, text, or distant objects tend to appear lighter in a high-resolution image than in a photo taken with a lower-resolution sensor.
However, resolution is just one of many factors that determine the final quality of an image, including some common settings you can change on your phone. Another important factor is focus: no matter how high resolution your lens is, if an image is blurry due to motion or other issues, it can still look blurry and poor quality. Lens quality is another crucial consideration; a good lens can improve sharpness, color and clarity from edge to edge.
Another is lighting. Cameras work by capturing light, so it’s no surprise that this is vital to the final quality of an image. If a scene is well lit, providing more light to the sensor, the result is sharper details, more accurate colors, and better contrast between dark and light areas. Low light can mean higher sensitivity (sensor sensitivity), which can introduce grain/noise, or a slower shutter speed, which increases motion blur. How a camera captures available light (which can be significantly affected by things like sensor size) and how it responds in low-light situations can be much more important than a variation in megapixel count.