Viewers
There are two kinds of Viewers: image file and process.
Image file viewers are static displays of files opened via the Open button on the main form or selected from the Forms File List via right-click.
Process viewers show image streams as they are processed (like a movie). By default the stack viewer is opened during job execution. Viewers for other processes can be opened via the “Viewer” menu on the main form. Process viewers are only opened when a job process produces a result (e.g. if no images are rejected then a Rejected Viewer will not appear).
Any number of viewers may be opened at any time but be aware that each viewer consumes memory and the process views place added demands on processing and can impede performance.
To Open an Image Viewer:
Press the “Open Job or View
Image” button:
Select Image file type in the Open File dialog:
To Save an Image from a Viewer:
Make sure that the desired Viewer is selected (click on it) then press the Save button:
Select the desired file type:
Information
The Information tab displays context sensitive information about the image. The current cursor location is shown at the bottom along with the intensity of the pixel at that location.
Magnify
Size to Window automatically sizes the image so that it always fits within the viewer window. Entering a number or moving the slider will uncheck this box.
Show Pixels checkbox forces the display to show whole pixels. Otherwise the image is resampled (bi-cubic).
Moving (scrolling) around the image: Magnification can produce an image larger than the window. Right-click and drag the mouse to move (scroll) the viewable area.
Scale Display
Adjust the display parameters. These controls are only applied to create the display bitmap and do not affect the underlying image data.
Numbers may be directly entered (typed) in the display boxes or changed by moving the sliders.
Minimum and Maximum sliders are elastic and the Maximum slider is progressive (play with them to see what that means).
Gamma applies exponential scaling. Gamma = 1.0 results in non-exponential scaling (linear scaling when DDP is not checked). Gamma may be used in conjunction with DDP.
DDP checkbox applies "Digital Development Process", which compresses the bright zone and stretches the dim zone.
DDP is the DDP-factor used to calculate the DDP function.
The auto scale button (elongated button on the far right) applies algorithmic scaling. A different algorithm is used for DDP vs. non-DDP. Auto-scaling is based on the visible area within the window (auto-scaling a zoomed-in view results in different scaling than a zoomed-out view).
Color
The result of color changes are shown on screen, but the underlying image data is not actually modified until the “Apply to Data” button is pressed.
Numbers may be directly entered (typed) in the display boxes or changed by moving the sliders.
The Red, Green, and Blue boxes and sliders are used to adjust color factors (ratios) and offsets. If “Neutralize Background” is checked then color ratios are offset by the background via slope and intercept (background is the intercept and ratio is the slope).
Apply to Data button replaces the underlying RGB data with new values calculated from the current values (including any effects of “Neutralize Background”, if checked).
Neutralize Background computes and applies R,G,B offsets to remove background color (e.g. due to sky pollution). The offsets are number also used as intercept points when adjusting RGB ratios, which minimizes hue-drift.
White Balance equalizes the ratios based on a small area surrounding the cursor click. Common white (or nearly so) objects are G2 stars (sun like), star clusters, and galaxies.
Display Raw: Raw Bayer (one shot color) camera images are not in fact color. Bayer images are actually multi-filtered grayscale, where each pixel is filtered (see Bayer Pattern below).
Display Colored Raw: This mode colors the pixels according to the respective filter. Note that magnification less than 1 will combine the pixels into a jumble. Set the Magnify tab to “show pixels” to correctly render the Bayer matrix. This mode is not particularly useful for anything other than a visceral illustration of the Bayer Matrix.
Display Interpolated: This mode constructs a color image from the Bayer pixels by interpolating the missing colors based on nearby pixels.
Bayer Pattern: Different cameras use different arrangements of the colored pixels that make up the Bayer patter. The Bayer pattern is automatically set for DSLR Raw images but most images from astro-cameras (e.g. FITS, TIFF, or SBIG formats) do not document the Pattern and thus must be set manually. If you do not know the Bayer Pattern for your camera then try different patterns to find the right one. (Correct color ratios are necessary for the image to look correct. So if you also do not know the native ratios for your camera then the correct Bayer Pattern may not look correct until you also set the Color ratios).