<p><strong>Short answer</strong>  </p>

<ul>
<li>Multi-channel coding in color vision refers to the different photoreceptors in the retina.  </li>
<li>Opponent-channel coding refers to the opposing color pairs: the red-green and yellow-blue axes. 
<br><br></li>
</ul>

<p><strong>Background</strong>  </p>

<p>I think you are referring to terminologies often used in color vision. </p>

<ul>
<li><strong>Multi-channel coding</strong> generally refers to different types of photoreceptors in the retina, namely <strong><a href="https://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html" rel="nofollow noreferrer">rods and cones</a></strong>. In terms of color vision, it is the cones doing the work. In trichromatic species, such as humans, there are three types of cones in normally sighted people, namely red, green and blue cones. So humans have a 3-channel color system, the same as your computer screen you are looking at now, namely R, G, and B channels.</li>
<li><strong>Opponent-channel coding</strong> refers to the opponent theory of color vision as proposed originally by <a href="https://en.wikipedia.org/wiki/Ewald_Hering" rel="nofollow noreferrer">Hering</a>. It basically states that our RGB color system defines color space by 3 opponent processes, namely a black-white, a red-green and a blue-yellow opponent system (Fig. 1). Basically it is theorized that red opposes green, yellow opposes blue and white opposes black (and <em>vice versa</em>). This means that colors are mixed between these channels (<em>e.g.</em> a reddish blue equals purple), but that colors within channels are mutually exclusive (<em>e.g.</em> there exists no such thing as a yellowish blue).</li>
</ul>

<p><a href="https://i.sstatic.net/UwAbr.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/UwAbr.jpg" alt="Hering"></a><br>
<sup>Fig. 1. Hering model of color vivion. source: <a href="http://psych.ucalgary.ca/PACE/VA-Lab/colourperceptionweb/theories.htm" rel="nofollow noreferrer">University of Calgary</a></sup>  </p>

<p><sub><strong>Reference</strong><br>
<strong>-</strong> <a href="http://webvision.med.utah.edu/book/part-vii-color-vision/color-vision/" rel="nofollow noreferrer">Gouras, Color Vision. In: Kolb <em>et al</em> (eds), <em>Webvision. The Organization of the Retina and Visual System</em>. Utah University</a></sub> </p>

CC BY-SA 3.0
2017-10-05T19:03:16.157Z
2017-10-05T19:03:16.157Z
AliceD
<p>I am looking for the definitions of </p>

<ul>
<li>Multi-channel coding</li>
<li>Opponent-channel coding </li>
</ul>

<p>And specifically in the context of visual adaptation. I have searched for information on the web and in books, but I am unable to find accurate definitions.</p>

CC BY-SA 3.0
2017-09-27T11:51:53.593Z
Welcome. Are you talking about color vision or something else? Could you provide some background information and please link any sources (to the book excerpt for example)
AliceD
CC BY-SA 3.0
2017-09-28T03:20:11.767Z
I'm talking about visual adaptation. I can't seem to find any explanation for what those terms actually mean.
Carl Wagner
<neuroscience><perception><vision><neurophysiology><sensory-perception>
What are the definitions of 'multi-channel coding' and 'opponent channel coding'?
Carl Wagner
# What are the definitions of 'multi-channel coding' and 'opponent channel coding'?

(Asked by: username_0 on 2017-09-27)

I am looking for the definitions of

* Multi-channel coding
* Opponent-channel coding

And specifically in the context of visual adaptation. I have searched for information on the web and in books, but I am unable to find accurate definitions.

**Tags:** neuroscience, perception, vision, neurophysiology, sensory-perception

> **Comments:**
> **username_1**: Welcome. Are you talking about color vision or something else? Could you provide some background information and please link any sources (to the book excerpt for example)  
> **username_0**: I'm talking about visual adaptation. I can't seem to find any explanation for what those terms actually mean.  

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## 1 answers

### Answer by username_1 on 2017-10-05. Score: 1

**Short answer**

* Multi-channel coding in color vision refers to the different photoreceptors in the retina.
* Opponent-channel coding refers to the opposing color pairs: the red-green and yellow-blue axes.

**Background**

I think you are referring to terminologies often used in color vision.

* **Multi-channel coding** generally refers to different types of photoreceptors in the retina, namely **[rods and cones](https://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html)**. In terms of color vision, it is the cones doing the work. In trichromatic species, such as humans, there are three types of cones in normally sighted people, namely red, green and blue cones. So humans have a 3-channel color system, the same as your computer screen you are looking at now, namely R, G, and B channels.
* **Opponent-channel coding** refers to the opponent theory of color vision as proposed originally by [Hering](https://en.wikipedia.org/wiki/Ewald_Hering). It basically states that our RGB color system defines color space by 3 opponent processes, namely a black-white, a red-green and a blue-yellow opponent system (Fig. 1). Basically it is theorized that red opposes green, yellow opposes blue and white opposes black (and *vice versa*). This means that colors are mixed between these channels (*e.g.* a reddish blue equals purple), but that colors within channels are mutually exclusive (*e.g.* there exists no such thing as a yellowish blue).

[![Hering](https://i.sstatic.net/UwAbr.jpg)](https://i.sstatic.net/UwAbr.jpg)  
Fig. 1. Hering model of color vivion. source: [University of Calgary](http://psych.ucalgary.ca/PACE/VA-Lab/colourperceptionweb/theories.htm)

**Reference**  
**-** [Gouras, Color Vision. In: Kolb *et al* (eds), *Webvision. The Organization of the Retina and Visual System*. Utah University](http://webvision.med.utah.edu/book/part-vii-color-vision/color-vision/)


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