mmdruler
Detect defects in a ruler.

The gray-scale image of the ruler is read.

a = mmreadgray('mm3.tif');

mmshow(a);

a

The close top-hat operator followed by a thresholding is applied.

b = mmthreshad( mmcloseth(a,mmsebox(5)),40);

Warning: converting image from scalar to uint8

mmshow(b);

b

The vertical lines longer than 50 pixels are detected.

c = mmopen(b,mmseline(50,90));

mmshow(c);

c

It closes ruler tick marks gaps.

d =mmclose(c,mmseline(15));

mmshow(d);

d

It detects all objects connected to the ruler tick markers.

e = mminfrec(d,b);

mmshow(e);

e

It detects all objects vertically connected to the ruler tick mark. Note that the 3x1 rectangle is used as structuring element in the vertical reconstruction.

f = mminfrec(d,b,mmseline(3,90));

mmshow(f);

f

The residues obtained from the previous image.

g = mmsubm(e,f);

mmshow(g);

g

It uses an opening by an elementary cross structuring element to eliminate the artifacts.

h = mmopen(g);

mmshow(h);

h

It detects the objects connected to ruler tick marks. A reconstruction from the ruler marks detected is applied.

i = mminfrec(h, b);

mmshow(i);

i

Overlay the detected defect over the original image

mmshow(a,i);

a,i