Understanding HoG output

[bricklemacho]

Thought I would follow up.  I have sorted out the visualisation
expectations.  I have been able to modify the visualisation output/
plot of the D&T paper. SOme simple maths can make the orientations
"parallel" if I so desire.    It also appears that the D&T paper plot
the orientations after block normalisation which also accounts for why
I was seeing different in gradients.  Anyway, I have a better
understanding now, so thanks everyone for your help.

Now to work out how to calculate HoG descriptor for a region rather
than a whole image.

Michael.
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