Remarks on blurring

I did a lot of capturing during the last weeks. I go through each published sequence and verify that blurring is ok. Doing this, I noticed recurring blur failures that could probably be solved by software and so make life easier for contributors and Mapillary better respect privacy:

  • Blurring of license plates that are perfectly readable fails when character size is below a certain size, example. I blurred the plate of the car on the right manually, but you can still decode the plates of the three cars in the middle.
  • It seems to me that license plates that are not horizontal are not recognized and blurred, example ( I blurred the plate manually)
  • From time to time I fall upon cases where a traffic sign is blurred but well detected by the traffic sign detection software. I understand that blurring and sign detection are two independent processes but it would be nice to have some interconnection.

I find road signs being blurred like big green ones on highways.

But the most common blur I see that isn’t needed are shadows under trees and certain patterns such as fences and roofing on houses.

I feel so tired blurring license plates and faces. The automatic blurring are ridiculously bad to the point that it is probably better to be turned off completely so we don’t have to manually unblur important information. It rarely blur things that’s supposed to be blurred anyway. Properly blurred photos looks nice and “professional”, but it is too much stupid work not worth it.

I second the remarks from raito. Actually, I don’t find the automatic blurring so bad, it catches a good deal of objects that actually need blurring. The problem is that it catches a lot of false positives too.

I shoot mainly in environments where the need of blurs is rare, say one in one hundred images. With the automatic blurring this results in an abysmal false positive to total blurs ratio.

Furthermore, I mainly shoot 360 images, in which case the use of the blur editor to check the need for blurs is too impractical, as it takes a lot of time and gestures to check the whole image due to the limited viewport. Therefore, I rather check the images with external tools before uploading, and take note of the only few which will actually need blurring.

With all its limitations, it’s probably still better to keep the automatic blurring and try to improve it, rather than turning it off completely. I guess that most sequences are not going to ever be manually checked, so the automatic blurring is still better than no action,

But for the sequences I manually check, a global “clear all” button acting on the whole sequence would save me a me a lot of time, without any risk of compromising the results.