[AD] An example of HLS colour-space

["AE" <ae-a@xxxxxxxxxx>]

Here is a program that demonstrates the use of the HLS colour-space and
compares it to HSV colour-space. It is based on the improved exrgbhsv I
submitted a month or so ago. It lets you select the colour using the HLS
colour-space as well as the RGB and HSV colour-spaces.

The code also contains non-optimised implementations of the following-four
functions (I'm currently working on optimised versions):

hls_to_rgb()
rgb_to_hls()
sv_to_ls()
ls_to_sv()

The latter two convert between HSV and HLS colour-spaces (the hue in both
spaces is equivalent so it is not used in these two functions as it is the
same property).

To see the difference, drag the leftmost S slider (HSV) all the way to the
right. Then you will be able to see the differences between HSV and HSL by
looking at the colour-bars. When the colour is at it's most colourful-ness,
the HSV saturation drifts to white, and the HLS saturation drifts to
medium-grey. V is from black to red, and L is from black to white via red.

Apart from getting different results when interpolating in the HSV and HLS
colour-spaces, the V (value or brightness) and the L (lightness or
luminance) represent two different concepts. Brightness corresponds to
percieved intensity of a coloured-light, and luminance corresponds to the
quantity of light used. Brightness is also a property of self-illuminating
objects, and lightness is a property of reflecting objects.


AE.

Attachment: excolspc.zip
Description: Zip compressed data