Check for RGB match (or close enough match.)
Say your color is MatchR, MatchG, MatchB
Color at a point is:
pointR = DrawingCanvas.SnapshotRedAt(loopindex("X")/DrawingCanvas.PixelScale,loopindex("Y")/DrawingCanvas.PixelScale)
pointG = DrawingCanvas.SnapshotGreenAt(loopindex("X")/DrawingCanvas.PixelScale,loopindex("Y")/DrawingCanvas.PixelScale)
pointB = DrawingCanvas.SnapshotBlueAt(loopindex("X")/DrawingCanvas.PixelScale,loopindex("Y")/DrawingCanvas.PixelScale)
How close is the point color to the match color:
distance = sqrt((MatchR-pointR)^2 + (MatchG-pointG)^2 + (MatchB-pointB)^2)
Check that distance is less than some threshold to find a match.
Use the project debugger or browser.log to print the values or display all the above values to the screen, so you can get an understanding of the range of values in your project.