How to make a dithering effect in blender? Something like this:
By the nature of the render engine, it does produce some kind of dithering, but How to get more of it? Is there a way to do that?
The picture on the right is dithering (dithering is a process of colour effects that the computer makes to make an image, video or animation to look like a higher resolution. The resolution is the same, but the effect is chеаting the eye like it is).
I assume you are referring to this kind of dithering:
Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and digital video data, and is often one of the last stages of audio production to compact disc.
Basically, it's used to break up bands that appear when you have too few colors in your image. For example, the image on the left is without dithering, the image on the right is with dithering:
You can turn up the amount of dithering noise in Render settings > Post processing, however this is really only meant for removing banding artifacts which sometimes occur in certain lighting setups (without reducing the number of colors).
For example (click on image for full size):
Note that blender can output full floating point deep color EXR images, so unless you plan on reducing the number of colors later (in which case you would want to dither the image when you reduce the colors), I'm not sure that more dithering would really do anything more than what the render settings option already does (breaking up subtle banding artifacts).
Achieving a dithering effect is possible but only on a per-object basis. I've adapted instructions from here. I'll be using the dither pattern shown below:
First you need to have your material set to only render a few colours based on lighting with constant falloff. That means no smooth light/shadow gradient across the object. Here’s the material setup:
Now that we have very discrete levels of lighting on our model, we have the ability to mask out these areas based on colour and replace the colour with anything we want. In our case, a dithering pattern.
In the compositor use the Key Color node to select the colour you want to mask out.
Bring in your dither pattern texture using the Texture node.
Use the ColorRamp node to make the texture colour match that of the Key Color node.
Finally, use the Mix node to combine it all together.
The results will need adjusting to your needs. You will also need to do this for each colour you want to have a dither pattern.
Blender doesn't support this kind of dithering, where the color palette is reduced but the pattern dithered to maintain tonal variation.
However you can get this result on the output image in image editors such as The Gimp by converting to index color.
Or automate with imagemagick if you need to perform this as a batch operation (for animations for eg).
I think the only really effective way to accomplish this would be to use the compositor, here is a link BlenderGuru compositor
Perhaps another option (assuming your using Cycles) would be to turn the samples way down, and use ambient occlusion with a low setting.
