Noise Tool

Adds random noise to an image with a "photons/count"
parameter.

Choose a source window for the image either by entering
a value (0 through 9) in the text area after the label
"source image" or by pushing the link button and then moving
the cursor to the desired window and pushing the left
mouse button (there should be a beep and the window
number will appear in the text area).

Choose a window for the result by entering a value (0-9)
in the text area after the label "noisy image". Any previous
contents will be destroyed so be careful. The loaded default
is #1.

The text box labeled "photons per count" can be modified to
represent the appropiate value for the image. For example,
many of the 1988 to 1992 SOUP images have about 50 to 100
photons per detector count. Some X-ray images may have several
counts per photon so that the value is less than 1. The program
accepts any positive value. Experiment.

Noise is generated using random numbers with a normal (i.e.,
gaussian) distribution with a width for each pixel that is
= sqrt(pixel_value/photons_per_count). For very low counts, a
Poisson distribution should be used but is not in this program.
The resultant value is forced to be GE 0 however.

To dismiss this help message, press help (in the tool widget) again.
To dismiss both the tool and the help, press dismiss in the tool.