The Two Foundations of the Direct Comparison Method: Stability and ExposureHave you ever wondered why painters don’t simply compare color by holding a brush with paint directly in line with the subject?
It seems logical and convenient.
In fact, artists throughout history have consciously or instinctively tried to match color directly.
However, such attempts proved ineffective for two reasons: the absence of a stable tool for comparison, and a lack of understanding of the need to synchronize the lighting between the paint and the subject.
Without these conditions, this way of working loses its meaning.
Stability of Comparison is a basic requirement for accurate color matching.
Let’s take a painter who tries to match a color using a brush for comparison.
Each time they check the color, they inevitably change the angle or position of the brush, and therefore the lighting on the paint.
Additionally, because the brush has volume and an uneven surface, different amounts of reflection fall on the paint.
This is enough for each new comparison to differ slightly from the previous one, creating the effect of a “floating” color.
The correct shade keeps “slipping away,” because each adjustment is made under slightly different conditions.
This leads to a large number of comparisons and accumulated errors.
The situation is similar with a palette knife.
Even a small change in the angle of the paint surface relative to the light source can significantly alter its lightness.
That’s why a palette knife also requires stable positioning during comparison — to avoid the same “slipping” effect.
The surface with the paint sample must return to the exact same position as before, ensuring the same amount of light hits it.
Only then can the color match be accurate and efficient.
Lighting Synchronization (Exposure)Let’s assume the painter has achieved full stability and always returns the paint sample to the same position.
Even then, another issue arises — the difference in lighting between the working area and the subject.
Painters rarely work in ideal lighting conditions, such as a steady overcast day when the subject and the paint are lit almost identically.
More often, they work in situations where the lighting on the palette and on the subject differs significantly.
Suppose the painter is working on a portrait.
They are near the studio window, and the model is seated slightly farther away.
As is well known, illumination does not decrease linearly with distance — it decreases by the square of the distance.
This means that if you double the distance from a light source, the illumination decreases by a factor of four.
Triple the distance — and it decreases by a factor of nine.
So even a small change in distance can result in a major difference in brightness, even if we don’t consciously notice it.
More light falls on the painter’s working area than on the model.
When comparing the paint to the skin tone, the paint appears lighter.
The painter is then forced to darken all the paints so they match the tone in direct comparison.
As a result, all the colors in the portrait turn out darker than they should be.
If you bring the finished portrait close to the model, the difference will be obvious: the portrait will look too dark.
And the opposite is also true:
If the model is more brightly lit than the painter’s workspace (for example, by a strong lamp), the paint will appear darker in comparison.
The painter will instinctively lighten it, and the portrait will end up too pale and washed out.
For the direct comparison method to function correctly, two conditions must be met: the stability of the sample and sufficient illumination — the paint sample must receive at least as much light as the object being painted.(Today, tools are available that provide the necessary stability and allow for lighting synchronization. These make it possible for the artist to apply the direct comparison method effectively in practice. For more — see ChromaStick and the Disc Palette.)