16
17
7. Choose
Open or Convert AVI File
from the
File
menu. The
Open or
Convert AVI File
window will appear (Figure 11).
8. Select the file location of the .avi video saved prior. At the bottom left of
the
Open or Convert AVI File
window, in the
Action
box, select
Open
as individual images. (Alternatively, the Convert to BMP files selection in
the Action box breaks the video into individual frames and saves them for
opening and processing later.) At the bottom right of the Open or Convert
AVI File window you can select the video frame number to start with (usu-
ally will be 0) and the number of frames to break out into individual images.
Use caution, however; opening many hundreds of frames at once can
be confusing and burdensome. Click
Open
. Now that we have multiple
images of the planet, we will combine the images into a single image. To
do this:
9. Select
Combine
from the
Process
menu.
10. In the
Select Images
window, click
Add All
. Then click
OK
.
11. The
Combine Images
window will appear. For
Align Mode
, choose
Planetary
. In the
Output
box, select
Average
.
12. You can see how each individual image looks by using the
Next Image
and
Previous Image
buttons. If you see an image that looks poor, you can
reject it from the stack by clicking the
Reject Image
button.
Note: At least one image must be used as the reference image for the stacked
images to be overlaid upon. The default uses the first image for the reference
image. If you reject the first image or otherwise want to use another image as
the reference, click the
Set As Reference
button. If the image currently cho-
sen as the reference is rejected from the stack, you will not be able to
Overlay
All Images
.
13. Click the
Overlay All Images
button. All of the selected images will stack
on top of each other to form one resultant image. Click
OK
. Adjust the
Screen Stretch Window
to
Planet
, and use
Save
under the
File
menu to
save your image. You can now perform any wanted imaging processing.
Dark Frames
A way to coax additional image quality out of the SSSSI-III is to eliminate
unwanted camera “noise” from captured images. While this will generally not
be needed for most types of imaging with the SSSSI-III, it may help to improve
image contrast in some cases.
To do this, “dark frames” must first be captured and averaged. Dark frames are
taken with no external light entering the camera. The image produced is a map
of the actual noise in the frame being produced by the camera. When a dark
frame is subtracted from a regular (“light”) image, the noise in the resultant
image is reduced. You will find, however, that the short exposures that can be
taken with the SSSSI-III will not contain much camera noise to begin with. So,
subtracting dark frames from images (prior to combining) will not have a great
effect on resultant images.
Note: To most effectively use dark frames to subtract noise out of resultant
SSSSI-III images, it is important to take dark frames close to the actual time of
taking the “light” images. This is because temperature changes will cause the
noise pattern in the SSSSI-III to change over time. So, it is best to take some
dark frames immediately before or after the “light” images are taken.
To take dark frames for subtraction from “light” images:
1. In the
Camera Control Window
, set the
Mode
to
Dark Color 1x1
.
2. Set
Frames
to whatever you set it to for taking actual (“light”) images.
Note: When taking dark frames, do not change any of the settings in the Setup
button from what they were (or will be) when “light” images are taken.
3. In the box beneath the
Mode
box, choose
Autosave
. Now set the number
of dark frames you would like the camera to take under
Autosave
(three
to ten will generally suffice, these will be averaged together), select the
file folder in which you would like to save the dark frames with Folder,
and enter in a
Base filename
for the captured dark frames. Typically the
name of the object being imaged with the word “dark” added, such as
“Mars1dark”, will be entered here. If “Mars1dark” is the
Base filename
,
and you choose to
Autosave
five images, then the images will appear
in the selected file folder as “Mars1dark_0001.fit”, “Mars1dark_0002.fit”,
“Mars1dark_0003.fit”, “Mars1dark_0004.fit”, and “Mars1dark_0005. fit”.
Using the word “dark” in the
Base filename
will help you distinguish
between light and dark frames when combining later.
4. Click
Expose
, and MaxIm DL Essentials will indicate that the camera
needs to be covered to take a dark frame. Cover the front of the lens you
are imaging through, and then click
OK
. The camera will commence tak-
ing and saving the dark frames. Now that you have acquired several dark
Figure 11.
The
Open or
Convert AVI File
window breaks
video into individual images for
subsequent stacking.
