Easily remove white pixels from georeferenced plan
ArcGIS Pro 3.2.2:
I have a .tiff engineering drawing that I've georeferenced. I want to only see the black lines in the image; I want the white background to be removed so that I can clearly see the ortho beneath the georeferenced image.
I imagine there is a way to remove the white pixels using raster geoprocessing tools. However, raster analysis isn't my area of expertise, and I recall raster editing being fiddly work, so I'm looking for an easier option.
Idea:
- A button in the Imagery ribbon to quicklly remove white (and near-white) pixels from the existing image (not a copy/export).
I'm aware I can make the entire image semi-transparent so that I can see the ortho beneath the image. That works to a degree, but the ortho is still somewhat obscured by the semi-transparent white pixels. It would be better if the white pixels were completely removed, improving visibility.
With your raster layer selected in the contents pane, click on the "Raster Layer" tab in the ribbon, then play around with these Layer Blend modes, specifically the darkening ones. I think "multiply" will do what you want for a pure white background. Sometimes I have old plans with a more yellow background and a different blend mode is needed for that. No geoprocessing tools needed!
You can change the primary symbology to Classify (which creates 2 classes); change the color scheme to Black to White; then change the white to No Color. It just leaves the black lines.
Edit:
@CharlesGrant's Classify option worked too.
Just make a new dynamic greyscale layer using Raster Functions, since Classify only seems to work with greyscale.
Why is Primary Symbology > Classify unavailable for some images?
