The use of paint nib auto-masking was recently discussed here as an approach to tightening up a paint effect so that it better represents the details in a source image. Today’s post take a look at a different paint synthesizer editing technique you can also use to tighten up paint effects. It’s based on automatically modulating the brush size via local color differencing.
Building up a finished painting involves conceptualizing and then following a ‘paint strategy’ to build up the finished artistic image. You can think of a specific ‘paint strategy’ as a high level recipe to follow to put together a finished art image.
One typical paint strategy for building up a finished painting is to first start with a fairly large brush size for your paint strokes to rough in a painting. Followed by working with a progressively smaller brush size to build finer and finer detail in the painting over time.
You can emulate this kind of paint strategy by working with progressively smaller brush size and recording a series of individual auto-paint action steps in a paint action sequence.
Someone who is painting manually can also take care to not overpaint any image features while drawing individual paint strokes. And if they are working with a paint preset that allows for interactive brush size modulation (like with pen pressure), then they can also manually vary the size of their brush to avoid overdrawing source edge features.
The paint synthesizer provides a wealth of different modulation options that you can use to automatically adjust the paint brush size of an auto-paint preset. You can use some of these modulation options to simulate an artist manually adjusting their brush size as they paint to avoid overdrawing source features when building up a painting.
The brush size used for Studio Artist painting is a function of the control settings in the paint synthesizer’s Brush Source and Brush Modulation control panels. The initial master brush size is specified in the Brush Source control panel. The actual brush size used when painting is a function of this master brush size adjusted by any modulation settings in the Brush Modulation control panel. So the output of the Brush Modulation control panel is what is actually used for painting. In the Brush Modulation control panel you can specify things like a min and mix brush size, a brush size modulator, the # of different sizes, the kind of interpolator used to vary the brush size, etc. Choosing something like pen pressure for the Size Modulation would mean that as you pressed the pen down harder the brush size would vary between the min and max size settings. The Min and Max size settings are a percent variation of the main master brush size specified in the Brush Source control panel.
The first image below shows a simple auto-paint style generated by the paint synthesizer. The 2nd gallery image below shows the paint synthesizer’s Brush Modulation control panel settings for this simple paint preset. Note that the Size Modulation is turned off. So the brush size remains constant throughout all of the individual paint strokes that make up the final painting.
Note that the Size Modulation parameter has been set to the Local Color Dif option. This size modulator will adjust the size based on the color difference of the current brush location in the canvas (in relationship to the source image) vs the starting color for the paint stroke. As the local color difference increases, the brush size will get smaller (moving from the Max size to the Min size).
I wanted the brush to resize to 0 (and therefore not draw at all) if the local color difference got too large. And I set the # of Sizes from 1 to 30 so that there would be size variability as the color difference varied. The individual brush sizes are precomputed and then cached to speed up drawing. This is why you specify a specific number of different sizes.
The 4th gallery image above shows the result of auto-painting with the edited paint preset. Note that modifying the Brush Modulation control panel settings as described above leads to a much tighter auto-painted rendition of the source image.
This approach is not going to be as super tight as the auto-masked paint nib technique we described in a previous post. But it looks somewhat more natural, since the individual paint nibs applied to the canvas are not partially masked, but always complete drops of paint.
You can download the simple paint preset I used for today’s effect 8611.paint
The LocalLum Dif (local luminance difference) is another Size Modulation option you can use that produces an adaptive brush size modulation similar to the one described above (based on the Local Color Dif option). The brush size will be modulated based on the local color luminance difference when painting (as opposed to the local color difference).
The technique described above also works for manually drawn paint strokes. Try it out and watch how the brush size automatically adjusts to preserve source detail as you manually paint. This is a simple example of automatic assisted painting. The paint tool is trying to make intelligent decisions while you manually paint, to aid you in building up a particular artistic effect.
