Zeiss LSM 880 Operating Manual page 356

ZEISS
Fig. 490 Fourier transform with Max.Isotrop
disabled (strong solid line) and
enabled (blue stippled line). The
inner circle (light solid line) is the
Fourier transform
structured image
Fig. 491 Sketch of the influence of SR
Frequency weighting filter (blue
stippled
frequencies
Fig. 492 Influence of sectioning filter (blue
stippled
frequencies.
indicates increasing strength, the
double arrow the variance, which is
pre-defined
350
CHAPTER 1 - SYSTEM OPERATION
Left Tool Area and Hardware Control Tools
of the non-
lines) on the spatial
lines) on the spatial
The open arrow
000000-2071-464
If the Max.Isotrop checkbox is ticked, the
software will compute the high resolution image
with the same resolution in every direction that is it
does not use the highest frequencies in the
rotational directions and the Fourier transform will
be circle like (Fig. 490).
If the Auto Noise Filter checkbox is not ticked,
the Noise Filter slider is available, that can be
used to set the noise filter for the so called Wiener
de-convolution performed. The negative number
indicates the power to 10 for the filter. The smaller
the values (towards -11), higher frequencies are
allowed leading to noisier and crispier images. If
the Auto Noise Filter is ticked, the Noise Filter
slider is not displayed.
The SR Frequency weighing filter (also known as
HD goal filter) will affect more prominently the
higher frequencies. You can set the value by using
the slider or the spin input box. The filter is a kind
of cone that multiplies the Fourier transform of the
resulting image. Weighting changes the slopes of
the cone from the convex (towards 0) to concave
(towards 2) (Fig. 491). 0 is no filtering, 1 is a
straight line, <1 is convex, >1 concave.
You can toggle between Baseline Shifted and
Baseline Cut. In Baseline Shifted negative values
that can arise as an artifact by the Noise or Wiener
filter will be kept and an offset is added to the
whole image, so that the minimal (negative)
intensity becomes zero intensity (baseline shifted).
In Baseline Cut negative values will be clipped by
setting them to zero. No offset is applied.
The Sectioning (or Strength) filter removes the 0-
frequencies for the 0
variance. It also removes the 0-frequencies from
st
the non-shifted 1 (+1, -1) and 2
Therefore bumps and deeps might be occasionally
detected in the Fourier transformed image at the
positions defined to the rotation angle and grating
frequency. The higher the value, the more
stringent the filtering will be and more of the
lower frequencies will be removed (Fig. 492). Three
filter sliders and spin input boxes for the 0 order,
st
the 1 orders and the 2
left to right) for input.
All parameters will influence the Optical Transfer
Function (OTF) used for reconstruction. The shape
of the OTF in x, y is displayed in the OTF display
window below the Manual selection field.
LSM 880
th
order with a pre-defined
nd
(+2, -2) orders.
nd
orders are available (from
10/2014 V_01