Extract grid data from noisy image in Halcon

Question

I am trying to get clean grid data from this image (don't mind the tilt, it is incidental).

This means no noisy dots and a uniform grid representing the situation. I am doing fairly well using morphology, doing:

closing_rectangle1 ()
opening_rectangle1 ()
select_shape ('rectangularity')

in different orders and amounts to clean up some noise.

It is not as complete and uniform as I'd like to achieve, so I'm wondering if Halcon has a better way of doing this (other than morphology or as an addition to) that I am not aware of. The rectangle-orientation and pattern in the grid can be different but the size is always the same.

What is the exact output that you need from this image? Coordinates of the intersections or something else? — Vladimir Perković, Jul 20 '22 at 14:48
Uniform and complete regions, region center coordinates, coordinates of the intersections would probably also work I think. — Malinko, Jul 20 '22 at 14:56
Is the number of compartments always familiar e.g. 5x4 like now? — Vladimir Perković, Jul 20 '22 at 14:59

score 2 · Accepted Answer · answered Jul 20 '22 at 15:13

read_image (Image, 'D:/OneDrive - Subpixel d.o.o/Other/Stackoverflow/5/uZKGw.png')
threshold (Image, Region, 128, 255)
connection (Region, ConnectedRegions)
select_shape_std (ConnectedRegions, SelectedRegions, 'max_area', 70)

** One region is disconnected, which interferes with watershed algorithm
dilation_circle (SelectedRegions, RegionDilation, 1.5)

get_image_size (Image, Width, Height)
gen_image_const (Image1, 'byte', Width, Height)
paint_region (RegionDilation, Image1, ImageResult, 255, 'fill')

watersheds (ImageResult, Basins, Watersheds)
select_shape (Basins, SelectedRegions1, 'area', 'and', 4000, 8000)

** Transform everything to rectangles 2 (rect1 if you can ignore the angle)
shape_trans (SelectedRegions1, RegionTrans, 'rectangle2')

** Reduce the regions a bit to achive separation
erosion_circle (RegionTrans, RegionErosion, 3.5)

Awesome, watershed is THE solution to my issue! – Malinko Jul 20 '22 at 18:42 — Malinko, Jul 20 '22 at 18:42

Extract grid data from noisy image in Halcon

1 Answers1