1.1 HOW-TO Inspect

This HOW-TO deals primarily with image inspection methods. Other inspection routines are described in their relevent sections (see, e.g., astrometry inspection and photometry inspection). These and other inspection routines may eventually be linked from this HOW-TO formally, but they will never be described in any detail here.

1.1.1 Image Inspect Plot

Image inspection takes place primarily a MatPlotLib (PyLab) window and is illustrated in figure [*]. The plot contains a representation of the image with a title containing the filename of the frame being inspected. There are also pixel coordinate indicators for convenience. As this plot is within a Pylab window, all the familiar manupulation routines are available (e.g., panning, zooming, etc.) In addition to these, there are some single-key commands to create new plots that illustrate specific details around the cursor position. The next section gives details on these.

Figure: A typical image inspection window without the PyLab controls.
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1.1.2 Image Inspect Method

Image inspection can be called from any BaseFrame-derived frame, and is called by executing the frame's inspect() method:

awe> frame = BaseFrame(pathname='filename.fits')
awe> frame.inspect()

There are also a large number of options to control how the plot looks and even what is plotted. A summary of the options is given below:

pixels:
optional list or array representing the image to be inspected (can be MxN for greyscale, or MxNx3 for RGB)
zone:
tuple of (x0, y0, x1, y1) representing the image coordinates of the two oposing corners of the sub image to consider
kappa:
the factor by which the dynamic range is increased in units of sigma (0 gives full range)
iterations:
number of iterations in the kappa-sigma range clipping
cmap:
PyLab color map instance
vmin:
lower display range in native units (e.g. ADU)
vmax:
upper display range in native units (e.g. ADU)
interpolation:
type of interpolation the PyLab viewer uses (nearest, bilinear, etc.)
width:
width of the PyLab figure window (in inches)
ratio:
ratio by which to scale the figure height (default: x_dim/y_dim)
viewer:
external viewer to use in case the image is too large
force_viewer:
always use the viewer
subplot_size:
width and height in pixels of region of interest
contour_levels:
number of contour levels for the contour plot of the region of interest
num_bins:
number of bins in the histogram plot
extension:
extension of the filetype to save plot to (png, ps, or eps) None disables saving
compare:
compare this frame to its previous version using difference imaging (current-previous), pixels is ignored
level:
depth of query for previous version (0 goes as deep as possible) when compare is True
other:
a second of the same type of Frame object to replace previous when compare is True (if color is True, other can be a list of two images)
clip:
kappa-sigma clip each image prior to subtraction when compare is True
color:
use color combining (RGB) instead of differencing when compare is True (kappa, vmin/vmax only honored when clip is True), this image is R, other is B if single, other is [G, B] if it is a list (EXPERIMENTAL)

Also, there are a number of commands that work on an area around the current cursor position. A summary of these commands are given below:

q
closes the most recent plot window when pressed in the main window
SPACE
displays the X and Y coordinate (FITS standard unit indexed) and the count level
a
performs aperture photometry on brightest feature in the region of interest (NOT YET IMPLEMENTED)
c
displays a contour plot of the region of interest (see contour_levels)
h
displays a histogram of the pixel values of the region of interest (see num_bins)
r
displays a radial plot of the brightest feature in the region of interest
w
displays a wireframe plot of the region of interest
p
displays profile plots in both X and Y dimensions versus intensity (count level)

Please see the inspect docstring for more details and current details on both of these:

awe> help(frame.inspect)

1.1.3 Image Display Method

A display method is available for all frames:

awe> frame.display()

This will open up the frame in skycat, by default.


page generated Tue Apr 4 14:29:36 CEST 2017