Skip to main content

Notes on Color #6: Creating a Zorn Palette

Update: the palette for Krita is available here.

For beginners, limited palette is a useful tool for learning to use colors. Among many of those, the Zorn palette, used by Anders Zorn, seems popular in some ateliers.

There are a few variations of the Zorn palette. The version that I'm learning consists of the following base colors:

  • Ivory Black
  • Permanent White or Titanium White
  • Yellow Ochre
  • Cadmium Red Light
When painting, you are only allowed to obtain colors by mixing these base cases. Depsite of its simplicity, the palette is surprisingly powerful, especially for portrait painting.

Since I'm learning both painting and color theories, I find it interesting to make a digital version.

Mixing Paints

The process of mixing paints is rather complicated. It is somewhere between additive-average and subtractive. However the situation is simple because the Black and White has very few chroma, and the Red and Yellow are very close in the color space.

In this case we could get quite good estimation of the mixed color by taking (weighted) geoemtric means of the spectral reflectance curves. More details can be found here. A more realistic result can be obtained with ColorMixingTools. Here is a comparison, they look close enough.
Spectral Reflection Curves of Cadmium Red, Yellow Orche and their 1:1 geometric mean.

Mixing Cadmium Red and Yellow Orche using drop2color.


Then I plotted mixes of pairs of base colors in XYZ and CAM16UCS.

Mix of pairs of base colors in XYZ

Mix of pairs of base colors in CAM16UCS

Interestingly, the edges look quite straight. This means we could even simply use linear combination as a good estimate. Note that linear combinations does make sense in term of mixing lights, and it is much easier to compute.

Computing the Zorn Color Space

Now the task is to compute all linear combinations of the colors. More accurately, we want all weighted arithmetic means of these colors. This is naturally the volume enclosed by the convex hull of the 4 colors.

The convex hull may be computed in XYZ or a linear RGB space. Note that since XYZ and linear RGB are just linear tranformation of each other, the result color space are essentially the same.

To me it was not trivial how to arrange the color space into a palette. Note that the Zorn color space is a 3d volume, but a palette is ususally 1d or 2d. After some research I decided to put the volume in CAM16UCS, then take slices of the volume at different luma's, which fit the way I intend to use it in painting.

At last, just for fun, I also computed the convext hull in CAM16UCS for comparison, which may or may not make any sense.

Here's the result:


While both versions look simliar, the XYZ version seems better.


Producing the Palette

Now the palette can be obtained by taking samples of the volume at grid points. Here are two slices.

The Zorn Palette at J=35   
The Zorn Palette at J=65

I was also able to export the palette for Krita.

Zorn Palette for Krita.

Final Thoughts

While it is merely a quick hack with random decisions here and there. I reckon this palette would serve well in my learning of the palette.

The Zorn palette may be viewed as a simple specific version of color gamut masks, which I plan to study further. In fact I do have questions and complaints about popular implementations of gamut masks. For example, common implementations involve:
  • The HSV/HSL/HSY color wheel
  • A regular, fixed shape on the color wheel, regardless of the value.
However I don't find good color/math theories supporting these choices. As shown above, I expect the shape of the mask to be irregular and changing at different values.

On the other hand, probably it doesn't matter at all. After all this is merely a guide for artists. It is up to the artists to make decisions based on their knowledge and styles.

Comments

Drayldan said…
Hi, very interesting notes on Zorn palette, etc. Could you share your eady-made palette files for Krita here? ;)
Lu Wang said…
Sure. Here you go: https://github.com/coolwanglu/Zorn-Palette-For-Krita

Popular posts from this blog

Determine Perspective Lines With Off-page Vanishing Point

In perspective drawing, a vanishing point represents a group of parallel lines, in other words, a direction. For any point on the paper, if we want a line towards the same direction (in the 3d space), we simply draw a line through it and the vanishing point. But sometimes the vanishing point is too far away, such that it is outside the paper/canvas. In this example, we have a point P and two perspective lines L1 and L2. The vanishing point VP is naturally the intersection of L1 and L2. The task is to draw a line through P and VP, without having VP on the paper. I am aware of a few traditional solutions: 1. Use extra pieces of paper such that we can extend L1 and L2 until we see VP. 2. Draw everything in a smaller scale, such that we can see both P and VP on the paper. Draw the line and scale everything back. 3. Draw a perspective grid using the Brewer Method. #1 and #2 might be quite practical. #3 may not guarantee a solution, unless we can measure distances/p...

Qubes OS: First Impressions

A few days ago, while browsing security topics online, Qubes OS surfaced—whether via YouTube recommendations or search results, I can't recall precisely. Intrigued by its unique approach to security through compartmentalization, I delved into the documentation and watched some demos. My interest was piqued enough that I felt compelled to install it and give it a try firsthand. My overall first impression of Qubes OS is highly positive. Had I discovered it earlier, I might have reconsidered starting my hardware password manager project. Conceptually, Qubes OS is not much different from running a bunch of virtual machines simultaneously. However, its brilliance lies in the seamless desktop integration and the well-designed template system, making it far more user-friendly than a manual VM setup. I was particularly impressed by the concept of disposable VMs for temporary tasks and the clear separation of critical functions like networking (sys-net) and USB handling (sys-usb) into the...

Exploring Immutable Distros and Declarative Management

My current server setup, based on Debian Stable and Docker, has served me reliably for years. It's stable, familiar, and gets the job done. However, an intriguing article I revisited recently about Fedora CoreOS, rpm-ostree, and OSTree native containers sparked my curiosity and sent me down a rabbit hole exploring alternative approaches to system management. Could there be a better way? Core Goals & Requirements Before diving into new technologies, I wanted to define what "better" means for my use case: The base operating system must update automatically and reliably. Hosted services (applications) should be updatable either automatically or manually, depending on the service. Configuration and data files need to be easy to modify, and crucially, automatically tracked and backed up. Current Setup: Debian Stable + Docker My current infrastructure consists of several servers, all running Debian Stable. System Updates are andled automatically via unattended-upgrades. Se...