‘Kinds’ of Pixels

What is the difference between total pixels and effective pixels? What is the actual resolution of a camera?

This story was originally published in November 2014.

Nisha P, Kolkata

A CCD image sensor on a flexible circuit board. Photograph/Christoph Müller

A digital sensor is made up of millions of pixels. While most of these pixels are used to record the final photograph, there are some pixels that line the sensor on the edges of the frame. These extra pixels ensure that the image is recorded properly. So, while they are useful for recording the image, the final image does not compromise of these few pixels.

Hence, there are two separate terms—total resolution and effective resolution. The total resolution of a camera refers to the total number of pixels in the sensor. The effective resolution refers to the number of pixels in the image that is recorded. For general purposes, we usually refer to the effective number of pixels as the actual resolution, sine that is the resolution of the images that the camera delivers in the final image.