Erode / dilate preliminary implementation

[qpincon]

Adresses #1719.

This is mostly a copy / paste of the previous try of implementation by #1744

The dilate operation works well, however erode does not seem to work but rather just shift the whole black pixels to the bottom right. I really can't tell why. I tried to fill the mask with 0, 128 and 255, but the results are the same.

Original	Expected	Actual

If anyone has an idea as of why it happens, I'll gladly try to fix it!

[lovell]

Merci beaucoup for the PR Quentin, I'll try to take a look to see if I can work out why the erode operation is not working as expected.

[kleisauke]

The dilate operation works well, however erode does not seem to work but rather just shift the whole black pixels to the bottom right. I really can't tell why. I tried to fill the mask with 0, 128 and 255, but the results are the same.

This will be fixed via PR libvips/libvips#4240. Thanks for reporting this!

[faradaytrs]

Is there progress on this? upstream pr is already merged

[lovell]

@faradaytrs This is dependent on the future libvips v8.16.1. Please subscribe for updates.

[faradaytrs]

@faradaytrs This is dependent on the future libvips v8.16.1. Please subscribe for updates.

seems like it has been released

[lovell]

The main branch has now been updated to use the latest libvips v8.16.1, which supports the erode feature.

@qpincon If you're still interested and available to help with this PR please can you rebase and test, thank you.

[lovell]

Rebased and landed via commit 031c808 - merci beaucoup Quentin!

[qpincon]

Thank you, sorry for not responding earlier!