I want to share a new tool that’s available on gumroad called Colour Constructor that helps with determining how local color is affected by light. In other words, we are familiar with the theory of cool light creating warm shadows and vice versa – this tool will help you create those conditions and test them. This could be used if you wanted to do a painting of sunset (with a reddish light for example) or at dusk (say a dark blue-violet light for instance) to test out and apply how different local colors would be influenced under these light conditions or others you might imagine. The tool requires working with RGB sliders for mixing color which may be unfamiliar (if you work with mixing physical paint you’re working with the CMYK model rather than RGB, won’t go into subtractive and additive light color theory here), however with this tool you can also use HSB sliders (basically hue, value and saturation – HSB actually stands for hue, saturation and brightness) so this will help in creating your “local” colors.
It’s true that there are 3D programs that do this in addition to other properties in the world of optics, however those programs are complicated and even when one is familiar with them require time setting up environments with lights and objects with materials to test them out whereas this program gets you right to it very simply and very quickly. In addition to that none of those 3D programs such as 3D Studio Max or Maya can compete with this price of $7.
You may be questioning the value of this tool and think it’s unnecessary because it won’t contribute to the knowledge of color theory that you have. If that is the case I would ask you to consider having a look at it before dismissing it. If you test it out yourself you may come upon some results that you didn’t expect. For example, a blue object or a green object in red light will appear black, you won’t see any of the blueness or greeness in the local color.
In summary I would say as artists we have a great new tool available to us that has previously only been available to the CGI community and is simple to use and affordable.
Here is my own color test using a blue light to see how local red color would be affected.
Here are some youtube videos demonstating its use