No doubt that when we shop for our new big screen LCD, Plasma or DLP, we are looking at the web for reviews,  specifications and price comparisons.  The specification that seems to be the most misleading is contrast ratio.  We have seen numbers as low as 50,000:1 to as high as 5,000,000:1 for TV screens larger than 40-in.   We consulted with industry experts and the majority agree that these inflated numbers are in fact meaningless.

Before we go into the details of  why these numbers are meaningless, it is important to know:  What is Contrast Ratio?

Contrast ratio is a  measurement of  the difference of light between the brightest white and darkest black that can be produced onscreen by a TV display.   When watching movies or broadcasts, content typically has transitions from bright scenes to dark scenes and a mix of the two.  For example,  watching the Dark Knight Blu ray there is a scene where the camera is panning over a nightime scene of Gotham City.   You have dark elements in the picture as well as lights from the city lights and from the offices in the building.

Contrast is the ratio between the white and black parts in the image.  A contrast rating of 300:1 means that the luminance or brightness level of the white areas in the image is 300 times brighter than that of the blacks.  The larger the contrast ratio, the greater the difference between the brightest whites and the darkest blacks a display device can produce.    Contrast is an important image attribute that affects our ability to perceive both image brightness and image detail.  Without a sufficient level of contrast, images appear flat with the blacks and white taking a gray shade while finer image detail would be lost.

There is an industry standard methodology to measure contrast ratio typcicall referred to as ANSI or On/Off contrast ratio.   The standard ANSI is considered the more accurate measurement since it takes into account the combination of alternating whites and blacks scenes.   The ANSI contrast is measured with a pattern of 16 alternating black and white rectangles – also referred to as the ‘checkerboard’ test pattern. The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio.  This measurement typically can yield numbers as low as 600:1 to 15,000:1.   In effect in this example, this number represents that white is 15,000 times brighter than black.

Now back to these inflated numbers.   Manufacturers have chosen to calculate contrast ratio based on a “dynamic” contrast ratio for which there is no industry standard of measurement.   This dynamic contrast ratio number is a purely calculated number based on a measurement of a full black field and a measurement of a full white field.  This can easily inflate the number to 500,000:1 or even 4,000,000:1 when you consider that the display could even be turned off when manufacturers are measuring black.   The reality is that no man or woman watches TV with either an all black screen or an all white screen.  Therefore, these inflated numbers are in fact meaningless.

Our advice when shopping for your new big screen TV:

1.  Use contrast ratio only when comparing TVs made by the same manufacturer.  For example,  Panasonic to Panasonic, Samsung to Samsung, Mitsubishi to Mitsubishi, etc.  By comparing contrast ratio to different manufacturers is like comparing apples to oranges.

2. Compare either static to static or dynamic to dynamic but don‘t compare static to dynamic.

3.  Contrast ratio is just one of many specification and factors to consider when buying a TV.   For us men in the cave, contrast ratio should be down on the list of deal-breakers because the measurements simply aren’t consistent from manufacturer to manufacturer.   Instead, use your eyes to determine if the contrast meets your viewing  needs.

4.  Consider your home environment.   Your viewing environment will also affect the perceived contrast.  For instance, bright environments make black scenes look blacker while dark environments makes black scenes look grayer.

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