I've been trying to implement this paper from Boris Epshtein, Eyal Ofek, and Yonatan Wexler, the pioneers of Stroke Width Transform .

On computing the gradient direction, given the equation:

theta = arctan( Gy / Gx )


  • theta = is the resulting angle
  • Gx = is the X gradient component
  • Gy = is the Y gradient component
    (both Gx and Gy are from the gradient maps)

Now, my question is, are the values of Gx and Gy in RGBA (or ARGB) Color Space? or since the values of R,G and B are equal due to gray scaling, are we going to use the (8 bit) value from any of the color components (R,G, or B)?

  • 1
    $\begingroup$ Does it make a difference? $\endgroup$
    – D.W.
    Mar 7, 2017 at 23:51


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