Image-sequencer: Add option to export edge-detected image with black background

[tech4GT]

Desired output

• [ ] Export image with black background
• [ ] Add support for jpeg images

[jywarren]

This is a follow-up to https://github.com/publiclab/image-sequencer/pull/168 !! Thanks!

[Ankit-Singla]

Hi,
Is this issue still open?
If so, I would like to work on this one if it's okay?

[tech4GT]

@Ankit-Singla this is a relatively difficult issue, we would love your help here though!! Don't hesitate to ask if you get stuck! Thanks!!

[Ankit-Singla]

I was thinking to present it as an input to the user, whether he/she wants the background to be white or black in the existing 'Detect Edges' module. Does this seem fine, or should I integrate this alternatively. @tech4GT
Thanks

[tech4GT]

@Ankit-Singla Taking an option will be nicer! Thanks!!

[harshkhandeparkar]

@tech4GT @jywarren I am working on this (almost done). I'm actually going to complete the module with hysterisis. I think I have found out a pretty good way of doing that. The black background is working. Just a few more lines of code needed to complete hysterisis. Will open a pr soon 😊