Some Variables in the Resolution Equation

Some Variables in the Resolution Equation

When manufacturers list the number of pixels on a camera, they can use either the total number of pixels, which is standard, or the effective number of pixels, which is the number of pixels that are actually used. The law requires that both of these numbers be recorded, but you may need to do some digging into the cameras manual to find out this information. 

Effective or not, pixels are not the only variable in digital camera resolution. There are several other important factors to consider:

* Interpolation algorithm
* Sensor design
* The actual lens
* In the case of zoom lenses, you should consider focal length
* Image position
* Is it orientated horizontally, vertically, or diagonally?
* Scene contrasts
* Vibrations

Comparing two different cameras' megapixel ratings would be pointless because of the differing degrees of freedom.

Using resolution that is measured in pixels can be used as a loose comparison for the amount of information a sensor can capture; it doesn't always measure the quality of the final image.

A 6-megapixel camera actually puts out twice the image as a 1.5-megapixel camera in a two-dimensional image. When doubling megapixels in regards to resolution, it is actually necessary to multiply the number by four.

We get more information regarding the quality of the image by comparing pixel density.  How closely the pixels are to each other provide a way for us to know how much detail we can get on a photo.

If they are too far apart, they won't be able to show as much detail as if they are closer together if everything else is the same.  However, if they are too close together they can have problems with "noise" or when information from one pixels bleeds onto the next pixel. Noise only occurs when the camera circuitry isn't of high enough quality to correct the information bleeding onto the other pixel.