How can I save only the drawing as an overlay?

[liamslo]

Summary
I would like to draw on an image, then remove the image so that I have an overlay against a transparent background. I have tried a few different methods to accomplish this, but have run into the following issues:

• 'Objects' seem to only refer to the shapes (triangle, circle, rect). It does not appear that there is functionality to save a free or line drawing, then place it back onto the screen - is this correct?
• As a workaround, my thought was to make the base image all white by increasing the brightness, and then add a Remove White or Color Filter to only leave behind the (red in my case) drawing. The brightness works, but I cannot find any information on how to add the color filter or remove white from the API. I have tried a few different variations of:
  getInstance().applyFilter('ColorFilter', {'Threshold': 100}).then((res: any) => { console.log(res) })
  but have not had any success. I have tried the same for Remove White, but am not sure what the types I should be using are.

Is there any solution to this issue? To reiterate, I would like to draw on top of an image, remove that image, then download just the drawing. Kind of like tracing.

Thank you.

Version
3.15.2

[liamslo]

For anyone that is having the same issue/trying to do the same thing, this was my work-around:

getInstance().applyFilter('Brightness', {'brightness': 100}).then((res: any) => { getInstance().applyFilter('removeColor', { color: '#FFFFFF' }) console.log(res) })

That will remove the background image, while keeping the drawing in tact. I don't know how good of a workaround it is, but hopefully it helps someone in the same boat.