Ellipticity Limit
Ellipticity Limit
The tracking process is able to detect images which represent multiple
particles in a number of ways. The [S Upper size limit] option sets the the
upper size limit of "blobs". If a blob exceeds this limit, then under some
circumstances DigImage will consider the blob to represent two particles
(see the particle tracking overview for more details).
Simillarly, multiple particles within the same blob may manifest themselves
by the ellipticity of the blob exceeding certain bounds. This option sets
the limit on the ellipticity, evaluated in terms of the x-y correlation
coefficient for pixels falling within the blob. If this limit is exceeded,
then DigImage may either ignore tha blob or consider it as two particles.
The probability with which the blob will be treated as multiple particles
is determined by [qPE Premium if ellipticity exceeded].
Ellipticity limit: upper bound on correlation coefficient ?
If the x-y correlation coefficient of the pixels in the particle is less
than the value given by this entry, then the blob will be considered a
single particle, at least on the grounds of ellipticity. The absolute value
of the correlation coefficient limit is in the range 0.0 to 1.0. A value of
1.0 allows all blobs to be treated as single particles.
If exceeded then Ignore or consider as Two particles ?
Responding with <I> will cause all blobs with an ellipticity greater than
the prescribed limit to be ignored. On the otherhand <T> allows the blob to
be treated as two particles, the first as a normal particle, and the second
with a premium given by [qPE Premimum if ellipticity exceeded].
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DigImage User Documentation
Stuart Dalziel,
last page update: 19 February 1996