DIGITAL CAMERA - MEGAPIXEL RATING & RESOLUTION

 

What is a pixel?

Before understanding the concept of megapixel rating it is important understand what pixels actually are. Pixels are also known as the Picture Element. Just as film grain was used to create an image in a conventional camera, pixels collectively create images that we see on a digital screen display. Generally the higher the pixel count within a digital image, the sharper the image. Digital cameras that produce a higher pixel count generally produce better images making them more suitable for enlargements or allowing more possibility for image cropping.

What is a Megapixel? What is Megapixel Rating (MP) ?

Digital camera sensor megapixel rating and the digital camera's resolution capabilities are directly related. Apart from the quality of the camera optics ( lenses ) and software, digital camera resolution is the other important factor that will determine digital image quality. The megapixel rating or MP is the standard used to determine digital camera resolution, however the quoted megapixel rating of a digital camera may not always be what it is cracked up to be and there are issues that need to be mentioned when talking about a digital camera's megapixel rating.

In calculating digital camera resolution or megapixel rating, we firstly look to the camera sensor chip. It is the horizontal sensor count multiplied by the vertical sensor count divided by one million will give you a digital camera's MP ( Megapixel Rating ) Generally speaking, the higher a camera's megapixel rating the better digital resolution is said to be. Superior image quality is achieved largely with more megapixels. Putting other factors such as lens quality, firmware or software aside for the moment , it higher quality CCD chips of higher megapixel rating that are important criteria for comparing digital cameras. Problems do arise however when comparing megapixel ratings, as different digital camera manufacturers may arrive a an particular MP by using different standards from another manufacturer .

Comparison of Megapixel (MP) Ratings - Avoiding Simple Traps

Although Megapixel rating and resolution are important performance indicators in camera comparison, there are traps to watch out for when assessing differences between types and brand of cameras and their quoted MP's. Digital camera buyers are often duped by digital camera manufactures quoting megapixel rating to their advantage. For example, a modest linear resolution increase ( in CCD or CMOS sensor count ) results in a large total pixel increase, thus manufactures and camera stores like to quote small advances in megapixel rating that an unsuspecting consumer perceives to be greater than they are in reality. This is because a small liner increase in the number of pixels in just one direction (either horizontal or vertical) results in a seemingly large pixel total for the image area. It would quite easy for a camera buyer to believe that resolution gains are doubled by upgrading a 4 megapixel camera to and 8 megapixel camera. In fact in order to double the resolution of a 4 megapixel camera one would require a 16 megapixel camera. Small increment steps between some camera models are not as significant as you may easily perceive, when you consider that in order to double resolution of a camera image sensor, you require four times the amount of image sensor area.

Effective Resolution Vs Total Resolution

Another potentially misleading megapixel figure is total resolution. A digital cameras total resolution refers to the total number of pixels on a CCD chip. For various reasons however many pixels on a chip are often not used to produce the image. This may be because some of the pixels are used in a chips circuitry to calculate charge or simply because degradation around the edges renders those pixels unusable. Therefore the total Resolution figure is not the best way to gauge the capabilities of a camera chip.

Another term known as effective resolution refers to the number of actual pixels used to produce a digital image. As many pixels on a camera chip are not utilised, so it is the effective resolution figure that will provide a truer measure of the resolution capabilities of a digital camera.

Interpolated Resolution and Digital Resolution

So far we have only talked about figures that represent the optical resolution of a digital camera and how easily these figures can presented to give a favorable description of a digital camera's capabilities. However there is another figure, known as interpolated resolution ( sometimes also known as digital resolution) that can artificially boost the resolution figure. In the case of digicams Interpolated resolution is usually a process where digital camera software uses mathematical algorithms to average the information from two true pixels. The result being a third pixel created for every two true pixels . In other words, interpolated resolution creates extra pixels that are mathematically generated. In such cases camera manufacturers or camera stores sometimes quote the interpolated resolution which is a higher figure than the original optical resolution.

When reviewing the specifications or making comparisons between digital cameras it is the true optical resolution that is a more reliable indicator of image quality.

Go to>> part 1 - Choosing Digital Cameras

Digital Cameras Basic Comparison