Yesterday I showed you how I created my base render that I’m going to be using to demonstrate digital painting effects and techniques. I applied some basic postwork in GIMP (Photoshop or similar would be equally good) to get it cleaned up and ready to work with. This included blending in spot renders to correct facial proportions and skin tone, plus removing unwanted shadows and highlights. Anyone working from a photo would also deal with skin blemishes and other cosmetic improvements, but in 3D we have the advantage of dealing with perfect models. In fact, we’re more likely to be found adding that kind of thing in ‘for realism’!
How I reached my own end result isn’t actually all that important, since you’ll now be working with a render of your own. More than likely you have a portrait of a beautiful girl, or some other person or fantasy being that inspires you. Just as likely, many of you will find my own render an odd choice. I happen to like ‘interesting’ faces and would be bored working on a cover girl type render. The inspiration part of this process is as personal and subjective as it gets, though. Just make sure you pick an image you love and you won’t get bored.
From this point on, we’re looking at filters and techniques that can be applied to any 3D portrait.
Quick, Free and Easy Painting Effect with GIMP and G’MIC
My first suggestion for adding a painted look to your 3D art has to be the G’MIC Brushify Filter. Why? Well it’s not only one of the quickest ways, but one of the easiest to apply, and there’s zero cost involved. That’s right. We’re using an open source plug-in for open source software, so anyone can try this one.
What you Need:
- GIMP – GNU Image Manipulation Program. This works across all popular operating systems.
- G’MIC – GREYC’s Magic for Image Computing. This is an entire image processing framework but can also sit neatly inside GIMP as a plug-in, giving you easy access to over 450 filters.
Say Hello to G’MIC
If you have GIMP installed, simply download G’MIC and then unzip the contents to your GIMP plug-in directory or run the installer. You should now be ready to go. Open up GIMP. G’MIC can be found under the filters menu along the top, however if you don’t have an open image it will be greyed out. You’ll be able to select it just as soon as you open an image-format file in GIMP.
If you have any problems with installing GIMP or G’MIC, gimpchat.com is a good place to get answers.
Using the Brushify Filter
You will see something similar to this when you open G’MIC.
Currently there are 18 different filter categories (not counting the About menu), each which can be expanded to find many different filters within. These are all alphabetical, so it should be a quick step for you to find the Artistic category and from there to click on Brushify.
My default settings have Ellipse as the pre-selected Shape. If you have that too, I’m going to assume all the other default settings will also be the same as mine. You will see in the preview window that an ellipse-shaped brush effect has been applied to your image. Hopefully it looks pretty good. If so, click Apply. The filter will now work its magic. This is not one of the quick filters and could take 30 seconds or so to finish.
How did you like the result? This is what I got on my portrait. The close-up shows it at full-size.
Kind of nice, with a strong brushwork effect. Personally, I wanted something more subtle, so I played with those settings. Let’s go through them. As you change a setting, watch the preview window which will show you the result.
Brushify Brush Parameters
First, you have brush Shape. I only had one layer so I’m ignoring the top two options which relate to layers. The remaining options are: Rectangle, Diamond, Pentagon, Hexagon, Octogon, Ellipse, Gaussian, Star and Heart. Each will give a different look to the brushstroke effect, with angular shapes giving more jagged results and gaussian having more blurring in the effect.
Ratio will apply the strokes finely at 0.00, getting increasingly blocky up to 1.00. If for example you want to use Heart as the shape and want those heart shapes to be obvious, use Ratio at 1.00. I’m sticking with Ellipse at a low value (0.20).
Number of Sizes chooses how many different brush sizes you want to use. A single brush size won’t look all that convincing as a painting and can make details too blocky. You can take it all the way to 16. Because I was using a subtle effect, I was able to keep the number low (4). This still had enough variation that a small brush could be applied to eyes and a larger one to more solid areas of colour.
Maximal Size will put a limit on how large the biggest brush stroke will be. Minimal Size is presumably a percentage of Maximal Size. Taking Maximal Size quite low will give you almost a fur effect. Again, because I kept the end result subtle, I needed to keep the Maximal Size large enough for the ‘brushwork’ to show. Around 50 worked well for this kind of portrait.
I didn’t mess with Number of Orientations, which changes how many brushstroke directions are evident. You can get some cool effects by sliding this down to 1. At 24, I was impressed at how the brushstrokes seemed to follow the contours of the face, for example they flowed down the nose and circled the eye. Play with this one until you are happy with the result.
If you have Preview Brush at the bottom ticked/checked, you can see what Fuzziness does as you dial it from 0 to 10. Basically, at 10 you have a lot of distortion and ‘breaking up’ of the brush stroke, at 0 you have none. I really like the stippled effect of a full-on 10 setting here. However, I chose for this example to use a low value of 2.75.
Smoothness applies more or less blur to the brush shape. Contrary to what you might think, it gives a more refined look at 0. I didn’t like it at high values but if you want the look of slapped-on paint you will want to push it higher than if you are going for finely-painted. I set it at 1.75. I would however probably continue to experiment with this and Fuzziness.
Light Type, as I understand it, affects the texture by simulating light hitting the strokes in different ways. The option None gives a creamy, smooth effect but you lose out on texture so it would be better suited to larger images. Flat gives lots of texture with almost a scratched looking surface and no 3d effect. Darken and Lighten will show you either the dark edge of the brushstroke (with a dirtier-looking result) or the light edge (a more glowing result). Full applies both of these for a full 3d look to the strokes. I went with Darken for this example.
At this point I had a result I liked, so I stopped here and applied the filter. But we’ll continue with the other settings to see what they do. The only ones remaining in Brush Parameters are Light Strength and Opacity. The first will increase (towards 1.00) or decrease (towards 0.00) the above light effects. So Dark will be darkest at 1.00, Lighten will be its lightest. Similarly, Flat and Full will have the most texture at 1.00. Opacity determines how strongly the effect is layered over your image, with 1.00 the strongest.
I would say you only need to adjust these if you need finer control. I admit I’m less clear on what these parameters do and the results were quite subtle on my image.
Density goes from 0% to 100%, but 100% will take some time to preview. It appears to apply the effect more (100%) or less (0% for none) thickly to the base image. Countour Coherence I’m not sure about. I suspect it may be to do with the way the brushwork flows around different areas of the image.
Orientation Coherence is a nice one to play with and has an effect on the direction of the brush strokes. Artistic results can be achieved at both extremes, which go from most regularity (0.00) to most irregularity (1.00).
Gradient Smoothness, again I’m not entirely sure what’s happening with this setting. For me it gives nicest results at a low value, and a look of more blending but less precision high up (10.00).
Turning Structure Smoothness to zero gives a stippled look which is appealing, while at 10.00 the brush strokes are longest and more obvious. Primary Angle and Angle Dispersion both made only subtle changes to my image so I can’t reliably tell you what these ones do, beyond what we can guess from their names.
In my example, I left all of these settings at their default values.
My Result: A ‘Painting’ Using G’MIC Brushify Filter
The animation shows a comparison of 1. the render without Brushify, 2. custom settings and 3. default Brushify settings. Unfortunately the small size of the gif might make it hard to see the more subtle custom effect but it looks good at a larger size. I will probably continue to adjust settings to further refine the result.
The Brushify filter was created by David Tschumperlé, the driving force behind G’MIC. I used the version that was updated on 22nd April 2016. I have described what each option appears to do based on my observations, to help out other users experimenting with this filter. If you need accurate and exact descriptions of the parameters of this filter, please consult the filter creator.
Thanks to David Tschumperlé for making such a great filter!