Parallel READ Access on Mats

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Hello all,

i want to speedup an algorithm (complete local binary pattern with circle neighbours) for which i iterate trough all pixels and calculate some stuff with it neighbours (so i need neighbour pixel access).

Currently i do this by iterating over all pixels with one thread/process. I want to parallelize this task by dividing the input image into multiple ROIs and calculate each ROI seperatly (with multiple threads).

The Problem here is, that the ROIs are overlapping (because to calculate a pixel, sometimes i need to look at neighbours far away) and its possible that multiple threads accessing Pixel-Data (READING) at same time. Is that a Problem if two or more threads reading same Mat at same Indices at same time?

Is it also a problem, if i write to the same Mat parallel but at different indices?