Suggest Thresholds for Particles
Suggest Thresholds for Particles
This option utilises the intensity histogram and particle statistics of
the tracking window to suggest an appropriate upper and lower threshold
for the particle tracking.
Examine which buffer for threshold ?
DigImage examines the histogram of the buffer specified here. Note that
you should not specify buffer 0. Typically you will wish to apply this
option to a number of different images in order to obtain the "best"
thresholds for the experiment.
Suggested lower threshold: ### --> !!R0
Suggested upper threshold: ### --> !!R1
Suggested number of steps: ### --> !!R2
These suggestions are intended as a guide line only. Typically they may be
used as the starting point when setting the thresholds. Subesequently fine
tuning manually may be required. Utilise [Z Count particles in buffer] to
see how well the threshold identifies the particles.
The suggested values may be obtained within a command file using the !!Rn
return value mechanism. The thresholds and number of levels are supplied
in the return variables indicated above.
During the evaluation of the image, a number of intermediate threshold
values are tested. In some cases these intermediate values may be of more
use than the final suggested thresholds.
Use these values ?
If you answer yes (<Y>), then the [T Lower threshold], [U Upper threshold]
and [V Number of threshold levels] entries will be set to the values
displayed here.
Errors, Warnings and Messages
Message:
Examining histogram...
Message:
Adjust thresholds to get appropriate distribution of particles...
Message:
Too few normal particles --> decrease upper threshold...
Message:
Too many normal particles --> increase threshold...
Message:
Too many particles brighter than upper thresholed --> increase...
Message:
Too few particles brighter than upper thresholed --> decrease...
Message:
Too many blobs rejected --> increase lower threshold...
Message:
Not many blobs rejected. Could try lower threshold...
Message:
Too many particles are very faint or noise --> increase lower threshold...
Message:
Not many particles found at lowest threshold. Try lower threshold...
Message:
Adjust lower threshold to maximise number of particles...
Message:
Adjust upper threshold to maximise number of particles...
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DigImage User Documentation
Stuart Dalziel,
last page update: 19 February 1996