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I have a raster map that has red areas in it. I want to extract the red areas as a polygon FC for spatial analysis purposes (find where red polygons overlap a different polygon FC).

Unfortunately, the source vector data isn't available from the government organization that produced the map. So I'm hoping to extract the red areas using GIS tools instead.

enter image description here

I've georeferenced the image in ArcMap. Now, I want to remove pixels that aren't red so that I can create vector polygons from the red pixels.

I think I need to use the Reclassify GP tool:

enter image description here

But I don't understand how to extract a range of colors (red) using that tool.

How can I extract pixels in the red color range using ArcMap GP tools?

ArcMap 10.7.1; Spatial Analyst Extension

PolyGeo
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User1974
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    Because your raster has colour, it's an image so its an RGB raster and is in fact a "stack of 3" rasters one for red, green and blue. Think what you have, you have the black lines of the base map passing through the red, how can you see those? They are different shades of red so in fact you may have hundreds of possible colour combinations, especially as the background appears to be grey scale. Reclassify is completely the wrong tool to use. As a first stab I would be looking at image classification tools such as isocluster, others may offer up superior solutions? – Hornbydd Nov 09 '22 at 16:55
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    Have a look at this Q&A? – Hornbydd Nov 09 '22 at 17:02

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