Add support for 16-colour terminals

[PK-cod3ch3mist]

The current generator does not support coloured output for terminals with only 16 colours like Terminal.app and Command prompt in Windows. For these, the only option is black and white ascii-graphics.

• Add a function that determines colour of individual ASCII characters to be printed while converting the image to 16-colours (4-RGB) space.
• It will be appreciated if done by using dithering so that the image looks similar to the true colour one.
• Both solutions using openCV/Pillow library functions or a self implementation of dithering are acceptable

Solutions that sit well with the current code structure, i.e. using options for True-Colour/B&W/4-RGB will be appreciated

[PK-cod3ch3mist]

Possible solution expectations/guide

What is done

Since the current script can already determine which character to print based on brightness, if you take a HSV (Hue-Saturation-Value) or HSL (Hue-Saturation-Lightness), the current script works out the lightness/value part. This means, once it is determined what the hue and saturation will be, the script can choose the ascii character for the brightness.

What is to be done

So what is needed is a function/algorithm that can map the hue and saturation of 24-bit RGB colourspace to 16 or 8 basic colours (which will then be assigned to characters that map to brightness).

[PK-cod3ch3mist]

Added support for 8-colour terminals