Segstartx

Segstartx is a variable used in image processing and computer vision to designate the starting x-coordinate of a region of interest (ROI) for segmentation algorithms. Typically paired with segstarty, it defines a two-dimensional origin within an image from which segmentation operations begin or are constrained.

In practical use, segstartx may be set to the left boundary of the ROI and combined with width parameters to limit processing to a subimage. Algorithms such as regional growing, thresholding, edge-based segmentation, or tiled processing often rely on such coordinates to improve performance or focus on a specific area. The value is usually an integer representing a pixel coordinate, and conventions vary by library, with origin commonly at the top-left corner of the image.

Because different projects adopt different naming conventions, segstartx may appear as x0, x_start, left, or similar terms. Users should reference the specific library or script documentation to ensure compatible coordinate systems and boundary handling, including off-by-one considerations at ROI edges.

See also segstarty, segmentation, region of interest, ROI, image coordinates.