### ImageMagick version

7.1.1-15

### Operating system

Linux

### Operating system, version and so on

Running portable binary (openSUSE Tumbleweed otherwise)

### Description

A follow-up on #6444. 

I was expecting the 3 channels to be in the conventional order: Lightness, Chroma, Hue. Observed Lightness, Hue and Chroma instead. This can be worked around, but was surprising. 

More importantly, I believe the conversion may not be correct, see example below.

### Steps to Reproduce

Trying to create a rainbow. I picked a lightness and chroma pair where the full hue spectrum can be represented in sRGB.

https://oklch.com/#69,0.113,0,100

```
./magick -size 100x100 \
canvas:'gray(69%)' \
gradient:'gray(0)-gray(255)' \
canvas:'gray(31%)' \
+combine Oklch -colorspace sRGB oklchgradient.jpg
```

produces

![oklchgradient](https://github.com/ImageMagick/ImageMagick/assets/137961841/2e44fc42-52a0-4959-89ba-8002351b0d48)

For comparison, here's one in HSB:

```
./magick -size 100x100 gradient:'gray(0)-gray(255)' canvas:'gray(49%)' canvas:'gray(89%)' +combine hsb -colorspace sRGB hsbrainbow.jpg
```

![hsbrainbow](https://github.com/ImageMagick/ImageMagick/assets/137961841/0a46fa94-5d94-46ee-916b-37ff2da6d234)

Thank you. I know this is a new colorspace and I greatly appreciate any effort that goes into its support.

### Images

_No response_
Oklch channel order, conversion bug
This is a GitHub Issue
repo:ImageMagick
owner:ImageMagick
Title : Oklch channel order, conversion bug
Issue date:

--- start body ---
### ImageMagick version

7.1.1-15

### Operating system

Linux

### Operating system, version and so on

Running portable binary (openSUSE Tumbleweed otherwise)

### Description

A follow-up on #6444. 

I was expecting the 3 channels to be in the conventional order: Lightness, Chroma, Hue. Observed Lightness, Hue and Chroma instead. This can be worked around, but was surprising. 

More importantly, I believe the conversion may not be correct, see example below.

### Steps to Reproduce

Trying to create a rainbow. I picked a lightness and chroma pair where the full hue spectrum can be represented in sRGB.

https://oklch.com/#69,0.113,0,100

```
./magick -size 100x100 \
canvas:'gray(69%)' \
gradient:'gray(0)-gray(255)' \
canvas:'gray(31%)' \
+combine Oklch -colorspace sRGB oklchgradient.jpg
```

produces

![oklchgradient](https://github.com/ImageMagick/ImageMagick/assets/137961841/2e44fc42-52a0-4959-89ba-8002351b0d48)

For comparison, here's one in HSB:

```
./magick -size 100x100 gradient:'gray(0)-gray(255)' canvas:'gray(49%)' canvas:'gray(89%)' +combine hsb -colorspace sRGB hsbrainbow.jpg
```

![hsbrainbow](https://github.com/ImageMagick/ImageMagick/assets/137961841/0a46fa94-5d94-46ee-916b-37ff2da6d234)

Thank you. I know this is a new colorspace and I greatly appreciate any effort that goes into its support.

### Images

_No response_
--- end body ---
