Talk:Edge detection

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In the practice of digital image enhancement, basing edge detection merely on numerical derivatives is too naive, and unrealistic. For each pixel of a digital image, one wants not only to decide if it is a candidate for membership in an "edge" but also to find the direction of that edge. [In particular, the edge direction is required for true sharpening]. One needs to analize a suitable collection of neighboring pixels (typically, those at horizontal and vertical distances up to 3) with respect to intensity as well as position. Although effective methods of doing this are not very difficult to develop, it seems that commercial software does not provide truly suitable implementations.