Feature request: Use register value as pixels per row when generating image?

**Is your feature request related to a problem? Please describe.**
At the moment, when using a register value (e.g. `$R0`) in the "Generate Image" operation's "Pixels per row" input, the output becomes `[object Object]` instead of an image.

**Describe the solution you'd like**
Earlier in my recipe, I count the amount of line termination bytes, and save them to a register.
It'd be great if it was possible to use this register value here.

**Describe alternatives you've considered**
There are none that I'm aware of.

**Additional context**