<p>Red <em>is</em> the gray scale channel (black/white). To generate a gray scale image copy the Red channel to the Green and Blue channels, set alpha to one and a gray scale image will result.</p>
<p>Of course that single channel can be used for many other purposes besides just gray scale image data. It can represent noise, a lookup table (LUT). The list is long and mighty.</p>

CC BY-SA 4.0
2021-07-30T12:10:27.933Z
So its the red channel just because it is the first in the classic rgb scheme?
Voß
CC BY-SA 4.0
2021-07-30T12:37:39.900Z
Yes, sometimes it is better to think of them as data channels and the r,g,b,a values are just the names.
pmw1234
CC BY-SA 4.0
2021-07-30T11:38:12.723Z
2021-07-30T11:38:12.723Z
pmw1234
<p>While programming something in Rust with the BevyEngine, I came across TextureFormats. My understanding is that those are used to define how the pixel data is handled. So Rgba8Unorm means that there are is a red, green, blue and alpha channel. Each of them is represented by an 8bit unsigned integer.</p>
<p>Since I only need a black/white image I read through <a href="https://docs.rs/bevy/0.5.0/bevy/render/texture/enum.TextureFormat.html" rel="nofollow noreferrer">this</a> list of available TextureFormats in the BevyEngine. But all the &quot;one channel formats&quot; have only one channel for red. Also <a href="https://docs.rs/wgpu/0.9.0/wgpu/enum.TextureFormat.html" rel="nofollow noreferrer">here</a> in the wgpu-rs crate. There are so many formats with only one channel for red.</p>
<p>Why is that. What is the purpose of having only the red channel. And why am I not abled to find a format that allows me to represent only B/W values. (Is that maybe an &quot;alpha only&quot; format?)</p>

<texture><color>
Why do some texture data formats only have the red channel?
Voß
# Why do some texture data formats only have the red channel?

(Asked by: username_0 on 2021-07-30)

While programming something in Rust with the BevyEngine, I came across TextureFormats. My understanding is that those are used to define how the pixel data is handled. So Rgba8Unorm means that there are is a red, green, blue and alpha channel. Each of them is represented by an 8bit unsigned integer.

Since I only need a black/white image I read through [this](https://docs.rs/bevy/0.5.0/bevy/render/texture/enum.TextureFormat.html) list of available TextureFormats in the BevyEngine. But all the "one channel formats" have only one channel for red. Also [here](https://docs.rs/wgpu/0.9.0/wgpu/enum.TextureFormat.html) in the wgpu-rs crate. There are so many formats with only one channel for red.

Why is that. What is the purpose of having only the red channel. And why am I not abled to find a format that allows me to represent only B/W values. (Is that maybe an "alpha only" format?)

**Tags:** texture, color


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## 1 answers

### Answer by username_1 on 2021-07-30. Score: 4 | Accepted answer

Red *is* the gray scale channel (black/white). To generate a gray scale image copy the Red channel to the Green and Blue channels, set alpha to one and a gray scale image will result.

Of course that single channel can be used for many other purposes besides just gray scale image data. It can represent noise, a lookup table (LUT). The list is long and mighty.

> **Comments:**
> **username_0**: So its the red channel just because it is the first in the classic rgb scheme?  
> **username_1**: Yes, sometimes it is better to think of them as data channels and the r,g,b,a values are just the names.  

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