Opening Operator
Building the Cantata Workspace
The opening is an elementary operator that accepts as parameters a function
and a structural element. This operator applies for signals, binary and gray scale images.
The structural elements can be criated by the following ways:
- using the tool
Struc. El. 3x3 to generate 3x3 planar elements;
- using the tool
Disk str. el.
to generate any disk, using three distance metrics: euclidean, city-block
and chess-board.
- Using the tool
Viff-> Str.El. to convert
any viff file to a structural element.
To build and experiment a workspace that performs some openings:
- select the $MMACH/viff/blobs2.xv image;
- visualize the image using display image;
- create a family of four structural elements of increasing size, using the
vdiskstr tool with the option Euclidian distance;
- perform the opening of the input image by these disks;
- convert the input image and its four openings to the BYTE type;
- add all the five images;
- display the result of the addition using a random color map.
Exercises
- Apply the opening operator on the 1D signal $MMACH/viff/signal1.viff.
Use flat and non flat structural elements. What differences could you
note between the efect of the flats and non flats structural elements?
- Apply the opening by the 3x3 square to the image $MMACH/viff/letters_noisy.xv.
- Apply to the image $MMACH/viff/letters_noisy.xv a family of four
openings. Chouse as structural elements the four segments of three points
including in the 3x3 square and with direction o, 45, 90 and 135 degrees.
Perform the union of the result of the four openings.
- Compare the results of the two previous exercices. What are the differeces
between the two filters?
- Apply an openning by an octagon (compostion of the cross 3x3 and the
square 3x3) to the image $MMACH/viff/disk_square.xv and take the difference with the original image.
- Could you see an application for the previous exercise?