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 Remove color
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104 Posts

Posted - Nov 18 2022 :  07:43:31  Show Profile  Reply

I need to automatically preprocess color scans in order to get the cleanest text for extraction.

Text recognition fails because the red line is too close to the text. Therefore, I tried to remove all red pixels using Proc.CastColorRange, but its tolerance starts to remove grey text pixels before all red pixels are removed. I tried also to clean up and increase image quality by implementing other preprocessing stages using AdjustBrightnessContrastSaturation, ConvertToGray & BN, WhiteBalance_AutoWhite, RemoveNoise, but all results got a poor or unstable recognition precision.

Has anybody an idea with which function the light red pixels can be removed by code without decreasing the text quality?



7376 Posts

Posted - Nov 18 2022 :  17:28:34  Show Profile  Reply
Hi Al

Yes, that is not an easy document to scan. I would try parsing the scanlines yourself to find "Reddish" pixels, e.g. where R > 200, G < 100, B < 100, and make them white.

See the example at:

If that is successful in nullifying the red pixels, then you might also then need to do some thresholding to try to increase the contrast between the text and the background.

Xequte Software
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