 IMPORTANT NOTICE! Never use a telescope or spotting scope to look at the Sun! Observing the Sun, even for the shortest fraction of a second, will cause irreversible damage to your eye as well as physical damage to the telescope or spotting scope itself. |
Undo Undo the last action. If there is noting to undo, you will receive a message box stating so.
Copy Copies the entire active image to the clipboard.
Toolbar
Toggles the toolbar on and off.
Status Bar
Toggles the status bar on and off.
Night Vision
Turns Night Vision on and off. (Night Vision turns all
screen items black and various shades of red to preserve the user's night
vision).
CCD Vision
Turns CCD Vision on and off. CCD Vision is much like Night
Vision except that blue is used instead of red. This is useful when taking
sensitive images or calibrations since CCD cameras are the opposite of the
human eye; they are least sensitive to blue light and most sensitive to
red light.
This menu is where nearly all image processing functions are located. Note
that all items on this menu except RGB Merge are grayed unless an image
file is open.
Image Scaling
This menu pick opens
a window where most of the image processing functions can be performed.
The sliders for brightness, and contrast are set to zero for a new image.
Any processing is relative to that zero. Selecting negative values will
decrease the brightness, and decrease the contrast of the image. The green
area graph shows the distribution of the pixels in the image, i.e. how many
pixels of a given intensity are there. The line shows the scaling that will
apply. The two red sliders can be used to chop off parts of the image data(to eliminate anomalies, for example).
The image can also be scaled according to linear, exponential, or logarithmic
functions. Additionally, a histogram equalization can be performed here.
These functions do not modify the raw image; rather they modify the way
the image data is displayed.
Process Image
This menu pick opens
a window where additional image processing functions can be performed.
The sliders for sharpen, brightness, and contrast are is set to zero for
a new image. Any processing is relative to that zero. Selecting negative
values will unsharp of the image. Values from -127 to 127 can also be entered
in the text boxes to the right of the sliders. Note that this brightness
and contrast is not the same as the one described under Image Scaling above;
this will change the appearance of the image, but can be reversed by restoring
the values to zero.
The other processing algorithms will perform different image transformations.
Only one at a time can be performed, and it can only be removed using the
Edit, Undo command. These transformations are primarily here for effect,
and will probably not enhance the image quality.
The gamma function only affects the view of an image, not the actual data
itself. The gamma value sets a correction factor to compensate for the non-linearity
of a video display. Valid ranges are 0 to 2.00. This will probably be set
around 1.50, but the best setting will vary from monitor to monitor.
Set Background and Range
This menu
pick opens a window that allows the user to stretch the dynamic range of
the image; the intensity of the background, and the range. This is the same
as pressing the arrow keys.
Blink Images
This will blink the
current image with a user selected one. The idea is to blink a current picture
of an area or object with a previous image; any changes will stand out.
This is most useful for asteroid or comet hunting.
The x and y offset sliders allow you to move the new image around over the
open image. This way, you can exactly align the two images and anything
different will stand out. This can be done while the images are blinking.
Also, the blink rate can be adjusted while blinking. The blink rate set
may not be achieved if it is very fast (25ms or so), and you have an older
system or graphics card. However, the blink comparator should perform well
on most PC's.
Rescale Image Size
This allows the
user to rescale the image to very specific values, either resizing one or
both axes, or fitting the image to a window.
The scale factor will scale both axes by the same amount. You can also resize
the image by dragging the window border with the mouse to the size you want,
then double clicking the
right mouse button.
Flip Horizontal
Flips the image about the Y axis. (creates a mirror
image). Flipping a second time will restore the original image.
Flip Vertical
Flips the image about the X axis. (upside down). Flipping
a second time will restore the original image.
View Negative
Turns the image into a photo-negative. can be useful
to see dim objects, or just as an interesting effect. Selecting this again
will restore the original image.
Information Opens the Image Information window.
This has prefilled out
information about images taken with the Pictor XT208, and may have information about imported images (depending upon format).
The fields that PictorView XT will fill out are: X and Y size, Bits Per
Pixel, Scale Factor, Zero Offset, Creation Date and Time, Exposure Time(length), and Camera Temperature.
Selecting Print Info will print a bordered report of the image information,
including file name if the image has been saved. This would be useful for
an imaging log.
Merge Images
The merge images function
allows the user to merge two images into one in a variety of different ways.
This function is especially useful on the Pictor 208, where the maximum
exposure time for a single image is low; two exposures may be taken and
combined to give nearly the effect of a single exposure twice as long. Also,
this feature can be used to average multiple calibration frames (e.g. dark
frames), a technique popular with many astronomers.
RGB Merge
This option opens a window
that allows you to merge three images taken with the Meade 616 color wheel
into a single tricolor image.
The scaling options let you decide how much weight to give to each image.
For example, if you try the merge and there is too little red in the image,
redo the merge with the red scaling set to 1.5 or 2. The offsets allow you
to align the three images perfectly to prevent oblong stars in the merged
image. You must calculate these offsets by hand by noting the coordinates
of the same star in each individual image, then calculating the offset from
there.
Subtract Dark Frame
This option
opens a window that prompts the user for a dark frame file name to subtract
from the current active image. Note that the dark file does not have to
be the same type as the active image. The directory will default to the
preset calibration directory defined in Set User Preferences. After clicking
OK, the system will subtract the dark frame from the current image. A dark
frame corrects for the thermal and electronic noise in the CCD chip, and
is probably the most important image processing function. For more information,
see the Viewing Images section.
After you select a file, you will be given the option to use scaling or
not.
Scaling
allows you to have a single
thermal frame that will work for all your images. To make a thermal frame,
take a regular dark frame of 5 minutes or so duration, then take a bias
frame. Subtract the bias frame from the dark frame, and the result is the
thermal frame. For the best possible results, you can average two thermal
frames using the Merge Images function.
To use scaling, enter the exposure time in seconds of the image and the
thermal frame, then the camera temperature for each exposure. (This can
be found in the Image Information window). Then click Use Scaling. For a
regular dark frame, do not enter anything in the dialog, and click No Scaling.
The option to remove cold pixels will average cold pixels out after performing
the dark subtract.
Subtract Bias Frame
This option opens a window that prompts you for
a bias frame file name to subtract from the current active image. Note that
the bias file does not have to be the same type as the active image. The
bias frame corrects for the base noise level in the camera. Note that the
bias frame is included in the dark frame. The only time a special bias subtract
is needed is when making a thermal frame. See the section on Viewing Images
for more information.
Subtract Bias Dialog: Exactly like the Subtract Dark Frame Dialog but with
a different caption.
Divide Flat Field
This option opens a window that prompts you for
a flat field file name to divide the current active image by. Note that
the flat field file does not have to be the same type as the active image.
The flat field will correct for differences in sensitivity between different
areas of the CCD chip. See the Viewing Images section and the Imaging Tips
section for more information.
Subtract Bias Dialog: Exactly like the Subtract Dark Frame Dialog but with
a different caption.
Select Subframe
This option allows you to draw a box around a portion
of the active image; when taking a new image, only the area inside the box
will be imaged. This allows quick downloading and viewing of a specific
object of interest.
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