This is a test page to check if your computer monitor/phone screen has a reasonable setting to cover the full colour contrast and brightness range. Most paragraphs are the default dark grey colour, while the next paragraph has a totally black font colour.
The image contains backgrounds at the limits of black, white and each of the three primary and secondary colours. Embedded within each colour block is a set of numbers, either 1, 2, 3, 4, 5 or 1, 2, 4, 6, 8 that represents the intensity variation from that background. Numbers are easier to see as their value increases. The mid-grey scale shows 1 to 5 brighter or darker. A “number” of X is used for 10 steps.
A value of 1 represents the smallest possible change from the background in the standard 8-bits per colour use by most computer systems. For example, in the red scale, the full red is 255, while green and blue have values of zero. The number 1 corresponds to 254, 2 is 253, and so on.
Gamut test for sRGB colour space
What you can detect will depend on a number of factors:
- The quality of your monitor and graphics card. This should not be major factor, although some monitors can degrade severely with age.
- your own eyesight
- hardware settings – overdriving brightness, contrast, or possibly other settings like backlight can cause the hardware to reach their limit too soon.
- software settings. Some graphics drivers provide various settings optimised for different scenarios, but improving one area comes with a degredation in others.
- Colour space – the sRBG is the standard used for web images, but setting other colour spaces, either in hardware or software might distort some ranges. Most moderately priced screens cannot even achieve 100% sRGB coverage.
- environment – The black scale might be difficult to read except in a darkened room. Even the background screen brightness can affect this.
On a reasonably well set up system you should be able to see down to at least 4 in each scale, and generally 2 on the grey scale.
If you cannot see the “X” then your system is probably significantly out of calibration for some reason.
