lichtkind

Finally - GTC 2.0, an all in one color library, is released ! This post will not be rehash (of) the (very) fine manual, but give you a sense what you can achieve with this software and why it is better than any other lib of that sort on CPAN. If you like to look under the hood of GTC, please read my last post.

When I released GTC 1.0 in 2022, it had 4 major features:

1. computing color gradients, between 2 colors in RGB
2. computing complementary colors in HSL
3. translating color names from internal constant set into RGB values
4. converting RGB to HSL and back

The HSL support allowed to add and subtract lightness and saturation (make colors darker, or lighter make them more pale or colorful). And by mentioning a very rudimentary distance computation and color blending we reached the bottom of the barrel.

GTC 2.0 expanded in all areas by a manyfold. Going from 2 (RGB and HSL) to now 17 color spaces (soon ~25) has a large effect. Not only being able to read and write color values from 17 spaces makes GTC much more useful, but also computing a gradient and measuring the distance in different spaces gives you options. Some spaces are optimized for human perception (OKLAB or CIELUV) other you would choose for technical necessity. Especially OKLAB and OKHCL are the hype (for a while) and GTC is the only module in CPAN supporting it. Almost all methods (beside ''name'' and ''complement'') let you choose the color space, the method will be computed in. And in is always the named argument you do it with: " in => 'RGB' " just reads natural.

And just to complete bullet point 1: gradient can now take a series of colors and a tilt factor as arguments to produce very expressive and custom gradients. The tilt factor works also for complements. If you use special tilt values from the documentation you can get also split complementary colors as needed by designers but the nice thing about GTC is, you could choose any other value to get exactly what you are looking for. Many libraries have one method for triadic colors one for quadratic. To get them in GTC you just set the steps argument to 3 or 4 but you can choose again also any other number. Complements can be tilted in all 3 Dimensions.

Beside gradient and complement came also a new color set method: cluster. It is for computing a bunch of colors and are centered around a given one, but have a given, minimal dissimilarity. New is also invert, often the fastest way to get a fitting fore/background color, if the original color was not too bland.

The internal color name constants are still the same, but this feature block got 2 expansions. For one you can now ask for the closest color name (closest_name) and select from which standard this name has to come from (e.g. CSS). These Constants are provided by the Graphics::ColorNames::* modules and you can use them also anywhere a color is expected as input. The nice green from X11 standard would be just:'X:forestgreen'.
But since CSS + X11 + Pantone report colors are already included 'forestgreen' works too.

There are many more features that will come the next week, the most requested is probably simulation for color impaired vision, more spaces, a gamut checker is already implement, gamma correction, will be implemented this week and much much more. Just give it a try and please send bug reports and feature requests.

PS. Yes I also heald a lightning talk about GTC in Berlin last week.