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| Q:
Does Image SXM automatically adjust the greyscale so that the full
range of greys are used? A: Yes, this is
the default behaviour. When reloading images with compensation
for tilt
or curvature
over a user-selected region of interest (ROI), the default
look-up table (LUT) is the same as for the original image. You can
override this by (i) pressing the option key to increase the contrast
so that the full range of greys is used within the ROI, or (ii)
pressing the shift key to decrease the contrast so that all of the
levels of the reloaded image lie within the LUT.
Q: Can I select a ROI to define a subtraction plane, and then subtract that plane from the whole image? A: Yes. Select
the region of interest (ROI), then select XY Tilt Compensation
from
the Compensation
submenu. The plane will be subtracted from the whole
image. The LUT will be the same as for the original image, unless the
option or shift keys are pressed (see above).
Q: Does Image SXM do some kind of background removal from images when they are loaded? A: By default,
Image SXM applies an xy tilt compensation
when loading SXM images. If
you would prefer to see the raw images (and apply compensation to
images manually), this can be switched off from the SPM Options dialog box.
Q: Do the compensation functions alter the real dimensions of the image? A: No. The
compensation
functions are designed to remove constant, linear or
quadratic functions (lines or planes) from the image data to make it
easier to see or measure features in the image. The apparent height of
any feature in the image remains the same, even though the number of z
levels displayed in an image that has been compensated for tilt or
curvature may not be the same as that of the raw (uncompensated) image.
Q: Is it possible to change the z scale of an image while maintaining its calibration? A: One of the
simplest methods is to use the controls in the Map window to change the
mapping between z values and greyscale. Use Apply LUT to fix the
greyscale according to the settings you have set. The z calibration
will be maintained. Alternatively, you can use Match LUTs to ensure
that all open images have the same mapping between z values and
greyscale, or Change LUTs
to specify the z values that you would like
to correspond to the black and white levels of the image.
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Steve Barrett November 2014 |
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