On 2020-11-15 at 04:38, tomas@tuxteam.de wrote: > On Sun, Nov 15, 2020 at 12:31:22AM +0100, Emanuel Berg wrote: > >> Hello, is there a tool/command/script anywhere that can overwrite >> with a single color (or make transparent) every pixel to the left, >> above, right, and below a certain other color? >> >> e.g., if one draws a loop of black, tell the program black is the >> border, the result would be only what is within the loop? > > Your request is a bit... unspecific. > > Are you (a) after a tool which you use interactively, where you > actually see the image you described above, and where you can click > into that loop to start the operation? > > Or is it (b) rather some kind or "batch mode", where you give the > program the image file *plus* the coordinates of that point inside > the loop where to start? > > For ease of search, the operation you're describing is usually called > "flood fill". If you are after (a), your friend is The Gimp; I guess > Krita will fill that bill as well. If it's (b), the usual standard is > "mogrify", from the ImageMagick suite. Look at [1] for the details on > flood fill. I think you may have misunderstood the request - either that, or I did. From the description of "flood fill", what it does is replace everything within a certain distance of a specified point with a specified color. That maps to "fill a specified region with a specified color", if the region is radius-based. What I understand the request to be is for a way to replace everything *outside of* a specified region with a specified color, where the region is *not* necessarily radius-based but may potentially be freeform. If I needed to do that, what I'd probably wind up doing is to select the desired region, copy it, paste it into an empty image, and adjust its position and the size of the image to suit. I don't know of any tool to automate the process to any meaningful degree. -- The Wanderer The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. -- George Bernard Shaw
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