What is this?

I first came across this LCD flicker effect when experimenting with animated GIF backgrounds in HTML on my PowerBook.
Dragging the window around in Mac OS X or Windows XP (which both allows real-time dragging and resizing of windows), or scrolling the static version of the diagonal pattern background on a LCD display will yield the same effect (try it yourself!).

> view video comparing the behaviour of a LCD to a CRT (requires quicktime)
> get quicktime

How to do it?

The effect is achieved by animating an array of pixel-wide diagonal lines at a very fast frame rate. But basically it works all the same at whatever rate; diagonal or horizontal or vertical. The key moment is when a frame moves onto the next one.
Click >here< for a slower version.

Also note that the higher the contrast between the 2 colours, the more prominent the effect. I chose not to use black on white at the front page for fear that it might trigger epileptic seizures.

Click >here< if you dare to look at it (opens a new window).


Note that the perceptual colour has been deviated as well. On this example, the value for the blue pixels are:

in RGB, R0; G174; B239;
in hex/web colours, #00AEEF

Yet the percepted colour on the flickering screen tends to give an almost pure cyan colour (R0; G0: C255 / #00FFFF).

On the contrary, when I view the page on a CRT display, it displayed what I originally thought I would see — the lines flowing down smoothly towards the lower left corner, without any colour deviation.

> back to main menu
> get flickering again


© Edmund Fung |