Vision - Find Black Area in Image

[thad_tensentric]

I'm a fairly new user to the Vision Development Module.  I have a set of images that I need to find an area that is free of markings/scuffs.  I'd like to use something like the find pattern VIs to find a black area in my image.  When I try either of the match pattern or match geometric pattern VIs, while specifying a totally black match image, I get an error in Vision Assistant.

I've attached an example of an image that I've processed.  I need to find an area that is open (no existing letters/scuffs, area is black).  I'd rather not find all the bright objects and then manually parse through that array, if there is an easier way to find an area lacking bright objects or to find an area that is black.

[thad_tensentric]

I think I will use the IMAQ Count Objects VI as a start and look for darkobjects of a certain size...then I can parse the found areas to see if one fits my size requirements.

I don't think that VI is available in Vision Assistant though, so I'll have to stitch the two together to try it out.

[Hatef.fouladi]

make binary image with thereshould and then use object analyse vi for finding black parts

[thad_tensentric]

I tried the find objects VI...I believe it didn't work for me because there is no border surrounding my desired "black area".

[Hatef.fouladi]

could you attach some example image ?