What is Dithering?

Dave Mostert
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What is Dithering?

Dithering is a very subtle sound that is used to test the accuracy of a watch. It is the sound that you hear when the seconds hand stops in between ticks.

Dithering is also used to check the stability of a stereo system. In this scenario, the small, noisy sound is fed into an amplifier and the volume is set at different levels. If the sound is not getting distorted as the volume is adjusted, the audio system is confirmed to be less susceptible to problems like hums and scratches.

In both scenarios, the word “dither” has been derived from the random motion. The concept is based on the impression that small, random movements make a watcher forget the need for precision.

Similar kind of concept is also incorporated in various hair-loss treatments. The main purpose of these therapies is to make the hair-growth take place at different speeds on different parts of the scalp to create a random pattern.

However, the word dither is also widely used in the computer science world; more exactly, in the art of programming.

The word is used as a verb to describe the action of a software, e.g. software dithers data. But we’ll get back to that later.

How Does Dither Work?

Dither is the application of any form of random activity in an effort to reduce stress in a patient. It is used to treat anxiety and severe emotional stress.

In programming, there are two ways to dither images and sounds. In the first, you divide the luma channel by a constant to reduce visibility and eliminate color. In the second, you dither in RGB or HSV to reduce visibility.

Instead of eliminating colors and visibility, dithering can be used to reduce noise in images or sounds. And to a lesser degree, seismic signal processing, by adding random noise to the signal.

The effect of adding this noise is that it reduces the intensity of high frequencies, thereby reducing noise. It works by introducing a variance in the signal that makes it harder to differentiate between random noise and signal.

It is important to note that dithering is an approximation that will never be perfect in any sense and that it will always have a perception of error.

As with most noise reduction algorithms, dither makes the assumption that the signal in question contains low frequency signals, and so adding high frequency noise is not a serious flaw.

Why is Dithering Important?

Dithering is one of the most misunderstood concepts in mixing audio. Compressors and expanders are often "dithering" tools and are quite often enough to "finish off your mix".

The word "dither" comes from the very old fashioned term of adding random amounts of very small numbers together. The process has been used to generate random numbers in the past and audio is not the only place this process has been used.

What is dithering exactly? The process of adding two or more sounds together to create a third as a kind of "glue" or "connector".

The concept exists in both an analog and digital format and is often misused. Most people in the digital domain of recording and mixing don’t really understand the process of adding noise to a signal.

What is perhaps important to understand is that by adding "random noise" you are no longer dealing with random noise. This can be a little counter-intuitive but the math is very sound.

Dithering might sound like a fuzzy concept at first, but you have probably already used it without even knowing it.

For example, JPEGS, MP3, and digital cameras all use pseudo random noise as a means to speed up the digitization process. This is the same process employed by your microphone preamp and audio interface.

Should Dithering Be Used When Mastering?

Mastering is an exciting process when you are almost ready to publish.

It gives you the opportunity to put a final polish on your work, to check that everything has been set up properly, and to make your manuscript as close to perfect as possible.

This is where things get a little bit tricky. Although you have put a lot of work into your manuscript so far, and you are very excited to see it on the virtual shelves, the editing can seem a bit tedious at times. Going through all the words over and over again just so you can refine your work can get boring.

What Else is Dither Used For?

While dither is primarily used in audio field to reduce noise, it is also used in photography to reduce ambient noise and can be used in the other parts of image processing like gradient maps, etc.

It’s helpful to think of dither as a box of crayons. Whatever colors are in the box, you can only get those out. But when you reach into the box, you mix up the colors a bit so you can go back to the same color later.

With dithering, you are intentionally creating and changing pixel values. This helps reduce the severity of quantization errors.

It’s not as good as creating a true continuous spectrum of color. But in many cases, dithering can get you close enough to get rid of the noise without creating a poor-looking image.

Summary

Dithering is one of the most important steps for achieving a high quality print on your 3D printer.

In this post we’ll take a closer look at dithering and what it is designed to do. We’ll also take a look at the different ways it can be implemented.

Additionally, we’ll look at a couple of different dithering algorithms and we’ll show you how they can be easily coded up and implemented in your slicer.

If you’re a beginner to 3D printing, mastering this basic technique can give you a huge advantage when it comes to getting great looking prints.

Dithering is an advanced technique, and as such it’s important that you are comfortable with the basics of 3D printing before you attempt implementing it in your own designs.