While exploring and manipulating the Mouse 2D program in the
Standard Examples folder and re-writing the code to allow the mouse to control
the alpha channel and the grayscale value, I was reminded of a gamma target
used to adjust a monitor. After investigating existing examples, I realized
that it would be easy enough to write the simple code required although
calculating the gamma using the mouse location was a more complex task and not
really relevant to this exercise. An example of an embedded gamma test can be seen
here http://perso.telecom-paristech.fr/~brettel/TESTS/Gamma/Gamma.html
The application window consists of a grayscale background.
The value of the grayscale is controlled by the x-axis of the mouse. The target
in the center of the window is composed of a square that’s greyscale value is controlled
by the y-axis of the mouse. A series of 1 pixel wide black lines over-write the
target every other row. This results in alternating rows of black and grey
lines 1 pixel wide. Because of the fine pitch, the human eye will average out
the target to a shade of grey.
The background and target values are manipulated until they
appear to match. (Try matching the values with your eyes wide open and then
squint slightly to see how accurate you were.) In a real gamma test, the values
would be compared mathematically to provide a gamma value. This program was merely
intended to reproduce the effect, but I can see it being embedded in a web page
as a quick means of checking viewing conditions or adjusting the way a single browser
page appears without having to readjust the system’s display settings.
The zip file can be found here.
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