vpix − primitive operations on the pixels of a VisionX image

vpix [if=<inputfile>] [of=<outputfile>] [th=<value>] [tl=<value>] [hi=<value>] [lo=<value>] [bf=<value>] [tf=<value>] [-neg] [-log] [-sqrt] [-scale] [-clip] [-range] [-wind] [-v]

Vpix performs a function or a set of functions on each pixel of the image data file. The implemented functions include: threshold,clip,scale,sqrt,log,negate, multiply by a constant and add a constant. The file created by vpix always has the same format as the input file. For many of these operations the data is converted internally to floating point format for processing.

bf=bval

The value of the parameter bval is added to all pixels.

tf=tval all pixels are multiplied by the parameter tval.

hi=hval

the high value for the pixels in the output file is set to hval. The default value for hval is 1.0 for all formats except unsigned byte (format 1) in which case the default is 255.

lo=lval

the low value for the pixels in the output file is set to loval. The default value for lval is 0.0.

-neg

logically negate all pixel values

-log

compute the logarithm of all pixel values

-sqrt

compute the square root of all pixel values

th=thresh

Threshold the image. All pixels having values greater than or equal to thresh will be set to hval; all other pixels will be set to lval. (see also -wind)

tl=ltrhs

sets the low threshold (input range limit) for the -wind option. Default value is zero.

-scale

set the range of the output pixels from lval to hval.

-clip

set all pixels with values higher than hval to hval and set all pixels with values less than lval to lval.

-range

selects a range of pixel values. Set all pixels with values less than ltrhs or greater than thresh to lval.

-wind

selects a window function. Map the input pixels in range lthrs to thresh to the range lval to hval (as specified by the limit parameters (th=, tl=, lo=, and hi=). Input pixels out of range are clipped. The default value for thresh for byte images is 255 and for other image types is 1.

-v

verbose operation. Gives some runtime information.

gn=sdev

adds psudo random noise to pixel with a standard devaition of sdev. This is useful for characterizing the performance of image filteres. For byte images beware of clipping. The same random sequence is generated each time the program is run unless the rs= parameter is set.

rs=seed

Specify the integer seed for the noise generator specified by the gn= option. For a given seed the same random sequnce will be generated.

A. P. Reeves