### ImageMagick version

7.1.1.22

### Operating system

MacOS

### Operating system, version and so on

OSX Ventura

### Description

-fx reports nan for standard_deviation

### Steps to Reproduce

I have this image.

![charts](https://github.com/ImageMagick/ImageMagick/assets/13458218/048421d1-4058-455e-a024-a8b5dfb69c7d)

This operation produces a reasonable image:

`magick charts.png -crop "429x144+535+155" +repage x.png`

![x](https://github.com/ImageMagick/ImageMagick/assets/13458218/8b32e796-813e-4d34-96c6-efc33c752a8d)


But getting the standard deviation for the same crop produces nan

```
magick charts.png -crop "429x144+535+155" +repage -format "%[fx:standard_deviation]\n" info:
nan
```

Is this a bug? Or am I misunderstanding something here?



### Images

_No response_
-fx reports nan for standard_deviation
This is a GitHub Issue
repo:ImageMagick
owner:ImageMagick
Title : -fx reports nan for standard_deviation
Issue date:

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

7.1.1.22

### Operating system

MacOS

### Operating system, version and so on

OSX Ventura

### Description

-fx reports nan for standard_deviation

### Steps to Reproduce

I have this image.

![charts](https://github.com/ImageMagick/ImageMagick/assets/13458218/048421d1-4058-455e-a024-a8b5dfb69c7d)

This operation produces a reasonable image:

`magick charts.png -crop "429x144+535+155" +repage x.png`

![x](https://github.com/ImageMagick/ImageMagick/assets/13458218/8b32e796-813e-4d34-96c6-efc33c752a8d)


But getting the standard deviation for the same crop produces nan

```
magick charts.png -crop "429x144+535+155" +repage -format "%[fx:standard_deviation]\n" info:
nan
```

Is this a bug? Or am I misunderstanding something here?



### Images

_No response_
--- end body ---
