AIPS HELP file for AHIST in 31DEC25
As of Wed Dec 11 5:30:00 2024
AHIST: Translates image intensities by windowed histogram
INPUTS
INNAME Input image name (name)
INCLASS Input image name (class)
INSEQ 0.0 9999.0 Input image name (seq. #)
INDISK 0.0 9.0 Input image disk unit #
OUTNAME Output image name (name)
OUTCLASS Output image name (class)
OUTSEQ -1.0 9999.0 Output image name (seq. #)
OUTDISK 0.0 9.0 Output image disk unit #.
BLC Bottom left corner of input
TRC Top right corner of input
XINC 0.0 29.0 Window size in X
YINC 0.0 29.0 Window size in Y
PIXRANGE Pixel range included in the
histograms.
HELP SECTION
AHIST
Task: This task converts the image intensities by performing a
histogram equalization over a window XINC by YINC pixels
centered on each output pixel. This operation enhances
the contrast in regions of low contrast and reduces the
differences between very bright and very weak
intensities. HISEQ performs this operation over the full
image (cube) while AHIST uses a 2-dimensional window
about each pixel.
Adverbs:
INNAME.....Input image name (name). Standard defaults.
INCLASS....Input image name (class). Standard defaults.
INSEQ......Input image name (seq. #). 0 => highest.
INDISK.....Disk drive # of input image. 0 => any.
OUTNAME....Output image name (name). Standard defaults.
OUTCLASS...Output image name (class). Standard defaults.
OUTSEQ.....Output image name (seq. #). 0 => highest unique.
OUTDISK....Disk drive # of output image. 0 => highest disk
number with sufficient space.
BLC........Bottom right corner in input image of desired
subimage. Default is entire image.
TRC........Top right corner in input image of desired
subimage. Default is entire image.
XINC.......Window size in X pixels - should be odd and at
least 5. Limit is 29, 0 => 11. XINC/2 pixels on
the left and right edges will be blanked.
YINC.......Window size in Y pixels - should be odd and at
least 5. Limit is 29, 0 => 11. YINC/2 rows on the
top and bottom will be blanked.
PIXRANGE...Pixels outside this intensity range are not
included in the hsitograms and are set to -0.001
and 1.001 respectively. PIXRANGE(2) <= PIXRANGE(1)
tells the task to use the full image intensity
range. It is often best to specify PIXRANGE(1) to
be just above the background noise level.
Otherwise the algorithm greatly expands this
background emphasizing the noise.
EXPLAIN SECTION