Be a Machine

A picture-grid test asking for squares with a fire hydrant. A street-corner hydrant crosses the lines of the grid. Most of it is flat red; its cap, its left side and a side nozzle are yellow, with ragged straight-edged borders between the two colours.
Outlined Twice  13 November 2026
A machine outlined this hydrant in 2021 and again in 2023. Red is where the two outlines agree. Yellow is where only one of them found a hydrant: 42% of it.

The photograph is real: Mapillary image 3808907185829188, taken by iamjeffrey on 1 September 2016 at 16th Street and South Van Ness, San Francisco. The outlines are Mapillary's own detections of a fire hydrant in it. I traced nothing and redrew nothing.

Counted in the crop: both outlines 31,790 pixels, only 2021 20,461, only 2023 2,309. The 2023 outline is a third smaller than the 2021 one.

Photograph: iamjeffrey / Mapillary, CC BY-SA 4.0. This picture carries the same licence.

Rebuild

tools/twice.sh src/mapillary_3808907185829188.jpg 640x640+2352+1170 src/outline_2021.png src/outline_2023.png out.png

Not kept

A rejected version of Outlined Twice.
Bars measured from the 2021 outline. Fine alone, but the find is that the two outlines differ, and one bar picture cannot show that.
A rejected version of Outlined Twice.
The same from the 2023 outline. Next to the other it says everything; a picture that needs its other half is a study. The crop also put the hydrant neatly inside one column, and the cut is the subject.