Enter the relative luminance of the lighter color and relative luminance of the darker color into the calculator to determine the contrast ratio.
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Contrast Ratio Formula
The following formula is used to calculate a contrast ratio.
cr = (L1+.05) / (L2 + .05)
- Where cr is the contrast ratio
- L1 is the relative luminance of the lighter color
- L2 is the relative luminance of the darker color
The relative luminance of the lighter color refers to the brightness of the color in relation to a reference white.
Relative luminance of the darker color refers to the perceived brightness of a color compared to a darker color within the same context.
What is a Contrast Ratio?
The contrast ratio measures the difference between the brightest white and the blackest black that a display can produce. It is a critical specification for displays, such as televisions and computer monitors, as it directly affects the quality and clarity of the visual experience.
A high contrast ratio is essential because it allows for better differentiation between dark and light areas on the screen. This means images and videos will appear more vibrant and realistic, with enhanced details and depth. A display with a low contrast ratio, on the other hand, may result in washed-out or dull visuals, where darker areas may appear gray or lack definition.
Example Problem
How to calculate contrast ratio?
- First, determine the relative luminance of the light color.
The relative luminance is found to be .215.
- Next, determine the relative luminance of the darker color.
For this example, the luminance is found to be .125.
- Finally, calculate the contrast ratio.
Using the formula, the contrast ratio is found to be (.215+.05) / (.125 + .05 ) = .220/.130 = 1.692 : 1.
Frequently Asked Questions
What does “relative luminance” mean in the context of contrast ratio?
Relative luminance refers to the brightness of a color as perceived by the human eye, in relation to a reference white. It’s a crucial factor in calculating contrast ratios because it helps determine how light or dark a color appears in a specific context.
Why is a high contrast ratio important for displays?
A high contrast ratio is vital as it enhances the differentiation between the darkest and brightest parts of an image, leading to more vibrant, realistic visuals. It significantly improves the viewing experience by providing better depth and detail in the display’s content.
Can the contrast ratio affect the energy consumption of a display?
Yes, displays with higher contrast ratios may consume more energy, especially if they achieve such contrast levels by increasing the brightness of the light source. However, the actual impact on energy consumption varies depending on the technology used in the display.
How can I improve the contrast ratio of my display?
Improving the contrast ratio can involve adjusting the display settings, such as brightness and backlight intensity, or using software solutions that dynamically adjust these parameters based on the content being viewed. For hardware improvements, choosing displays with better technology, like OLED, which offers high contrast ratios, is advisable.
