5th Intensive Course on Soil Micromorphology

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5th Intensive Course on Soil Micromorphology
Naples 2001
12th - 14th September Image Analysis
Lecture 8 Introduction to Binary Morphology
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Introduction to Binary Morphology Methods
Requires Segmentation of Image into Binary Form
(may require manual editting). Foreground
pixels are coded 1 - background 0 i.e.
Particles 1 (white), voids 0 (black) or Voids
1 (white), particles 0 (black)

• Erosion/Dilation
• Opening/Closing
• Kernel Shapes

Applications in Particle / Void Size Distribution
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Erosion strips one layer of foreground pixels at
edges of particles criteria based on number of
surrounding background pixels can be any number
1 - 8 pixel of interest is red white -
foreground black - background
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
a) foreground pixel removed for all
criteria. h) foreground pixel removed only if
criteria is set to 1 pixel.
Criteria may also specify that diagonal erosion
is (or is not permitted). Erosion not permitted
if diagonals not allowed in (j)
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Connectivity 4 - point connectivity allows
connection only up/down and side to side 8 -
point connectivity allows connection on diagonals
In 4 - point connectivity, foreground and
background are uniquely separated. In 8 - point
connectivity is background or foreground
continuous across diagonal? Both are not possible
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Erosion of original by one layer criterion - a
single touching background pixel
4 - point connectivity
8 - point connectivity
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Erosion by 2 and 3 layers 8 - point
connectivity All foreground features will
disappear.
Erosion by 2 and 3 layers 4 - point
connectivity Some residual parts of largest
particle remain.
Until particles disappear the residues are less
rough
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Dilation - the reverse of erosion Once again
similar criteria apply
4 - point connectivity
Individual features will merge
8 - point connectivity
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
8 - point connectivity erosion Equivalent to
passing a 3 x 3 kernel over binary
image. Where central point of kernel hits
background, all pixels covered by kernel are set
to background
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
4 - point connectivity erosion Equivalent to
passing a 3 x 3 kernel over binary
image. Where central point of kernel hits
background, all pixels covered by kernel are set
to background
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Non-standard Kernels may be used for special
effects
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Consider effect of one erosion followed by one
dilation.
This is known as an OPENING
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Red Residual after erosion Yellow
Recovered after dilation Blue Complete
particles lost Green Roughness lost on large
particles
Using careful housekeeping it is possible to
identify proportion of particles lost completely
and roughness lost from large particles.
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Components of opening - see next slide
2 cycles of erosion followed by 2 cycles of
dilation (8 - point connectivity)
2 cycles of erosion (8 - point connectivity)
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Light Green Roughness cycle 1 Dark Green
Roughness cycle 2 Red Residue
after 2 cycles Yellow Recovery cycle
1 Orange Recovery cycle 2 Blue
Particles lost cycle 1 Purple
Particles lost cycle 2
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
2 cycles of 3 x 3 kernel are equivalent to 1
cycle by a 5 x 5 kernel. Can be used for
efficiency
Alternative kernel for 5 x 5 which approximates
more closely to a circle (i.e. corner pixels are
omitted)
Kernel for 3 cycles giving a good approximation
to a circle / octagon).
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Standard Kernels for 9 x 9 array These 4 shapes
can be propagated to any size
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Procedure for feature size analysis
n 1
n n 1
Yes

• Erode n cycles
• Dilate n cycles
• Determine pixels lost as roughness
• Determine pixels lost from particles
• which disappear

Are particle residues left
No
Summarise results
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Grey Level Image
Binary Version
Schematic Representation of one erosion and one
dilation
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology

• BINARY MORPHOLOGY
• During successive opening, features tend
  towards circles.
• At each stage, protrusions are lost and this
  loss is related to the shape and roughness of
  grains.
• Finally, the remaining feature is lost and
  this is related to the size of the feature.
• Careful housekeeping is needed to differentiate
  between two types of loss, but procedure is
  well established in some branches of microscopy.
• The difficulty in achieving a reliable threshold
  makes the method generally unsuitable for
  analysing images of cores.

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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Binary Morphology used to determine Particle size
Distribution
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Roundness
Often defined relating to sharpness of asperities
on a grain
Sometimes roundness is defined by drawing
circles, but when exactly should on draw a
circle?
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Grain is successively opened with different
radii. The lighter colours (yellow) show parts
lost first. Ultimately remainder of grain
disappears when inscribed circle is as shown in
blue. If octagonal or square structuring
elements are used, then grain degenerates to
these shapes.
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5th Intensive Course on Soil Micromorphology -
Naples 2001 Image Analysis - Lecture 8 Binary
Morphology
Grain is successively subjected to opening of
different radii. The edge of the grain are shown
in colour where light colours (e.g. yellow
represent areas lost first - i.e. sharp), and
dark colours (e.g. dark blue are lost last. Can
be used as a more objective measure of roundness.