What is a Dynamic Contrast Ratio

Television or what most parents and teachers describe the appliance as the 'Idiot Box', has undergone a quantum leap since its invention. Some of us who have witnessed the black and white TV set without the remote, will remember fidgeting with the contrast, brightness and sharpness buttons of the television. The gray images on the TV were adjusted according to what your eyes perceived as a balanced contrast ratio.

What does Contrast Ratio Mean

The measure of a display system that is defined as the ratio of luminance of the brightest color, that is, white to that of the darkest color, that is, black the system can produce is called the contrast ratio. This measurement of the brightest color to that of the darkest color is seen on computer monitors, cathode ray televisions, LCD televisions and any similar electronic display.

What are the Methods of Measurement

In an all white screen compared to an all black screen, a full on/full off approach of measurement of static or dynamic contrast ratio is used. This method cancels out the effect of the room and gives the ideal ratio. As long as the room effects remain the same, equal light proportions are reflected from the display in black' and 'white' measurements, to the room and back. This causes the black to white luminance ratio to remain unaffected as the light levels of both the measurements inflate proportionally.

The other methods of measurement include a clear sector of the color filter wheel for the 'on' part and disabling it for the 'off' part. Another method is use of the ANSI contrast where a checker board pattern test image luminosity is measured simultaneously. In case of dynamic contrast ratio for LCD TV or some other display, the most effective method of measurement is the full on/ full off method. The static contrast ratio is measured by the ANSI contrast method.

What does Dynamic Contrast Ratio Mean

The definition is the number of the brightest white in a bright scene or image that is taken and compared to the darkest black in a low-lit scene resulting in a higher number. When a dark image is displayed, the black light lamp is underpowered by the display or decrease the aperture of the projector lens with the help of an iris. This proportionately amplifies the transmission through the LCD panel. So if the image is watched in a dark room, the potential static contrast ratio of the LCD panel in dark scenes is benefited. The emitted luminous intensity or brightness is measured in candela per square meter (cd/m²). Thus, higher the number, the screen will appear even brighter.

What is a Good Dynamic Contrast Ratio

When considering the best dynamic contrast ratio, you need to consider the human eye first and foremost. The human eye can resolve a contrast ratio of 1000:1 at any point of time. The human eye can also change its sensitivity to light with time. For example, if you happen to enter a dark room directly from sunlight, the eyes will take about half an hour to adjust. The overall contrast ratio it can resolve over is 1, 000, 000:1 over this time. So, a good dynamic contrast ratio should be anything over 1500:1. The best one for LCD TV will be above 10, 000:1.

The dynamic contrast ratio is measured in the factory using two panes. This means the panels of the same model having an underlying Dark and Light spot (Hot spot) are compared against each other.