Bitmap Overlay
This is the overlays window shown for a bitmap overlay. Many of
the buttons in the bitmap overlay window are the same as for the experimental overlay window, as
described here. However,
unlike an experimental spectrum, a bitmap spectrum does not contain frequency and intensity points.
It is therefore necessary to set the frequency scale manually by identifying two points on the spectrum with known frequency:
- For the first point, click the Xpixel 1 button, and then
click on the point in the bitmap spectrum. Enter the corresponding frequency at Frequency1 in the grid.
- For the second point, click the X
pixel 2 button, and then
click on the point in the bitmap spectrum. Enter the corresponding frequency at Frequency2 in the grid.
If you want to set the vertical scale:
- Click the baseline button and then click on a point on the baseline in the spectrum.
- Click the maximum button, and then click on a point on the highest point of the spectrum.
- If you need to change the vertical range produced (the default is
0 to 1) change the BaselineIntensity and MaximumIntensity values in the
grid.
Moving
the cursor to a point on the
bitmap gives an x and y pixel number in the status bar and, when the wavelength and
intensity scale have been set, shows the wavelength and intensity of
that point.
This is where the start and end frequencies, baseline and maximum
intensities are set manually. A frequency offset can also be
applied, if necessary.

This is where the points for the
start and end frequencies, and the points for the baseline and maximum
intensity will be entered (the numbers are entered automatically on
pressing the
,
,
and
buttons and clicking the
appropriate point on the bitmap).
This
shows and allows you to edit a comment on current item. The comment is
not used elsewhere and there is no limit on the comment length.
Toggle display between
fit to window and actual size.
Compact bitmap by
reducing to a single colour.
Cancel setting variables
by mouse.
Set point for Frequency
1 with the mouse.
Set point for Frequency
2 with the mouse.
Set baseline point
with
the mouse.
Set Maximum intensity
point with the mouse.
Delete peaks
from this overlay.
Discard bitmap outside
selected area.
Undo
work done with "Crop"
button.
Convert photographic plate spectrum to a conventional overlay, as shown in the example below.