In mixed mode HiRISE images, there is a tendency for every other line in the
ccd with the lower binning mode to be significantly darker or lighter than
normal image data would suggest. This program attempts to correct that
problem. 2 passes through a cube are necessary to perform the correction. The
first pass gathers information on each line of the cube to determine if the
striping phenomenon occurs in odd numbered lines or in even numbered lines, and
also gathers information to perform the actual correction.
The second pass through the data performs the actual correction, of which there
are two different types. The default, an additive correction, is of the following
form for each pixel
((Line[i-1]) + Line[i+1])
Pixel[i,j] - Line[i] + --------------------------
2
The other correction, a multiplicative correction of a similar style, is of
the form
Pixel ((Line[i-1]) + Line[i+1])
------- * ---------------------------
Line[i] 2
It should finally be noted that the striping pattern has been observed to
be most prevalent in a certain quardrant of the image, though that phase
is not the same for all images. In order to address this irregularitiy, the
line averages shown above are not for the entire line, but only for the
quarter of the line in which sample i exists.
Caution should be taken when running hidestripe: it should only be run on
images where different CCDs are run at different binning modes. Of those,
only channels that are not used in the highest binning mode of the image
should be corrected. For example, if an image has binning modes 1, 2, and 4
the CCDs with modes 1 and 2 may be hidestripe'd, but in an image that is
only binned in modes 1 and 2, the bin 1 CCDs are the only ones that need
the hidestripe correction.
