In today’s world we are surrounded by digital technology. It is everywhere – in our cameras, phones, video devices and computer screens. Pixels are a big part of this new digital technology – but what exactly is a “Pixel”?
According to Oxford Dictionaries a Pixel is;
- 1. a minute area of illumination on a display screen, one of many from which an image is composed: “the camera scans photographs and encodes the image into pixels”
To view what a pixel looks like check out this YouTube video –
The word pixel is based on a contraction of pix (“pictures”) and el (for “element”). Pixels are dots used to display an image on screen or in printed matter. When we view a printed image a pixel is a physical point whereas in display images a pixel is the smallest controllable element of a picture. Each pixel is a small sample of the original image; the higher the number of samples the higher the accuracy of representation of the original image. The intensity of each pixel varies depending on what portion of the image they represent. Color images can be represented in two modes: RGB or CMYK. With RGB each pixel is made up three dots of varying intensities of red, green and blue whereas with CMYK each pixel is made up four dots – cyan, magenta, yellow and black.
The number of bits used to represent each pixel determines how many colors or shades of gray can be displayed. For example, in 8-bit color mode, the color monitor uses 8 bits for each pixel, making it possible to display 2^8th power (256) different colors or shades of gray. As you increase the bit depth you exponentially increase the color and shades of gray capacity of each pixel (i.e. 12 bit – 2^12 (4096 colors and shades of gray).
This bit depth is also how the manufacturers categorize and price their cameras. The higher the bit depth the higher the quality of the file and it’s ability to capture individual colors and shades of gray in each pixel. The bit depth of a camera ultimately refers to the number of distinct levels of luminance a camera is capable of producing. This is a two to the power of factor mathematical relationship meaning a16-bit camera is capable of producing 2^16 or 65,536 distinct levels (of tone…irrespective of color) compared to a 12-bit camera which is only capable of producing 2^12, or 4,096 levels. We can see that the bit depth resolution relationship is nonlinear, instead it is an exponential relationship. What this means is that the bits of information in an individual pixel increases exponentially as you move up the bit depth scale as shown in the chart below:
There is however a cost associated with bit depth – as you increase the bit depth you increase the cost of your camera purchase. I am shooting with a 16-bit camera that typically costs 10x that of a conventional DSLR (14-bit camera).