Can't have a background annotation

[FredericLopez]

trafficstars

It should be possible to have the first element of a segmentation RLE element to be 0 to be able to label the background but it doesn't seem to be supported. I've tried to insert an arbitrary value in the counts element and reducing the corresponding amount in the next element but it doesn't work either.

It works correctly by appending 0 to the counts element in FiftyOne :