<p>Re separating RGB, I guess you are referring to Lance Williams' &quot;<a href="https://dl.acm.org/doi/10.1145/800059.801126" rel="nofollow noreferrer">Pyramidal Parametrics&quot; paper</a>.</p>
<p>I suspect he did it that way to fit in with the graphics system he had, but on modern GPUs (at least since I started developing them in 1992) the channels are not separate. The MIP map chain is likely to be just a set of <span class="math-container">$N \times M$</span>, <span class="math-container">$\lfloor \frac{N}{2} \rfloor \times \lfloor \frac{M}{2}\rfloor, ..., 1\times1 $</span> images <em>possibly</em> arranged semi-contiguously in memory.</p>

CC BY-SA 4.0
2022-09-27T00:38:03.430Z
I just looked at the paper--yes, you're right. I also edited the question to include a reference to the Wikipedia page, that shows this phenomenon.

Thanks. I think that this is my answer.
Adam Smith
CC BY-SA 4.0
2022-09-26T08:19:56.413Z
2022-09-30T11:12:39.583Z
2022-09-30T11:12:39.583Z
Simon F
<p>I'm trying to understand mipmapping.</p>
<p>It makes sense that you would have many pictures of your textures at different resolutions, and use the closest ones in size to what you need in order to avoid moiré patterns--that's logical. But a lot of the diagrams I've seen split out the R, G, and B channels: for example splitting a square into quarters, in which the top left is the red component of an image, the top right is green, the bottom left is blue, and the bottom right recursively splits the image up again, at a lower resolution.</p>
<p>So what's the point of splitting up the RGB? Why not just have a bunch of different-sized images of your texture? It seems that splitting them up is wasted work, since you'll ultimately just have to put them together again.</p>
<p>(There is an example of this phenomenon on the Wikipedia page for mipmapping, under the &quot;Mechanism&quot; heading.)</p>

<texture><mipmap>
Why does mipmapping separate out the RGB channels?
Adam Smith
# Why does mipmapping separate out the RGB channels?

(Asked by: username_0 on 2022-09-26)

I'm trying to understand mipmapping.

It makes sense that you would have many pictures of your textures at different resolutions, and use the closest ones in size to what you need in order to avoid moiré patterns--that's logical. But a lot of the diagrams I've seen split out the R, G, and B channels: for example splitting a square into quarters, in which the top left is the red component of an image, the top right is green, the bottom left is blue, and the bottom right recursively splits the image up again, at a lower resolution.

So what's the point of splitting up the RGB? Why not just have a bunch of different-sized images of your texture? It seems that splitting them up is wasted work, since you'll ultimately just have to put them together again.

(There is an example of this phenomenon on the Wikipedia page for mipmapping, under the "Mechanism" heading.)

**Tags:** texture, mipmap


---

## 1 answers

### Answer by username_1 on 2022-09-26. Score: 3 | Accepted answer

Re separating RGB, I guess you are referring to Lance Williams' "[Pyramidal Parametrics" paper](https://dl.acm.org/doi/10.1145/800059.801126).

I suspect he did it that way to fit in with the graphics system he had, but on modern GPUs (at least since I started developing them in 1992) the channels are not separate. The MIP map chain is likely to be just a set of $N \times M$, $\lfloor \frac{N}{2} \rfloor \times \lfloor \frac{M}{2}\rfloor, ..., 1\times1 $ images *possibly* arranged semi-contiguously in memory.

> **Comments:**
> **username_0**: I just looked at the paper--yes, you're right. I also edited the question to include a reference to the Wikipedia page, that shows this phenomenon.  Thanks. I think that this is my answer.  

---

