Filters can be used to change size and shape of objects in an image. [*] Concept map below assumes bright objects on dark background. For dark objects on bright background effect of min and max filters is inverted.
concept_map:>
graph TD
image --> max1[max]
image --> min1[min]
image --> max2[max]
image --> min2[min]
image --> d
subgraph rank filter sequence
max2 --> min3[min]
min2 --> max3[max]
max1
min1
d[max - min]
end
max1 --> dilation
min1 --> erosion
max3 --> opening
min3 --> closing
d --> gradient
subgraph morphological filter name
dilation
erosion
opening
closing
gradient
end
# figure: TODO
# figure_legend: TODO
activity_preface:>
Open the image, `xy_8bit_binary_two_spots_different_size.tif`, and explore how structures grow and shrink, using erosion and dilation
# activities:
# "Platform": "path/to/file.md"
exercises_preface:>
### Exercise 1
Fill in the blanks, using those words: "shrinks", "increases", "decreases", "enlarges".
1. An erosion _____ objects in a binary image.
2. An erosion in a binary image _____ the number of foreground pixels.
3. A dilation in a grayscale image _____ the average intensity in the image.
4. A dilation _____ objects in a binary image.
### Exercise 2
True of false? Discuss with your neighbour!
1. Morphological openings on binary images can decrease the number of foreground pixels.
2. Morphological closings on binary images never decreases the number of foreground pixels.
3. Performing a morphological closing a twice in a row does not make sense, because the second closing does not further change the image.
