imshift input output xshift yshift
input
List of images to be transformed.
output
List of output images.
xshift, yshift
Fractional pixel shift in x and y such that xout = xin + xshift and
yout = yin + yshift.
shifts_file =
The name of the text file containing the shifts for each input image. If no
file name is supplied each input image is shifted by xshift and
yshift. Shifts are listed in the text file, 1 set of shifts per image,
with the x and y shift in columns 1 and 2 respectively. The number of
shifts in the file must equal the number of input images.
interp_type = linear
The choices are the following.
nearest
Nearest neighbour.
linear
Bilinear interpolation in x and y.
poly3
Third order interior polynomial in x and y.
poly5
Fifth order interior polynomial in x and y.
spline3
Bicubic spline.
boundary_type = nearest
The choices are:
nearest
Use the value of the nearest boundary pixel.
constant
Use a constant value.
reflect
Generate value by reflecting about the boundary.
wrap
Generate a value by wrapping around to the opposite side of the image.
DESCRIPTION
IMSHIFT will shift an image in x and y such that:
xout = xin + xshift
yout = yin + yshift
The output image gray levels are determined by interpolating in the input image at the positions of the shifted output pixels. IMSHIFT uses the routines in the 2-D interpolator package.
1. Shift an image by (+3.2, -4.5) using a biquintic interior polynomial interpolant and boundary extension.
cl> imshift vys70 vys70shift 3.2 -4.5 inter=poly5 bound=neare
2. Shift an image by (-6., 1.2) using bilinear interpolation and boundary extension.
cl> imshift ugc1040 ugc1040shift -6.0 1.2 bound=neare
3. Shift a set of images using shifts listed in the textfile "shifts".
cl> page shifts
3.5 4.86 -2. 8.9 10.1 7.8
cl> imshift im1,im2,im3 im1.s,im2.s,im3.s shifts_file=shifts
The time required to shift a 512 by 512 real image by fractional pixel amounts in x and y is approximately 10, 20, 70, 120, and 120 cpu seconds for the nearest neighbour, bilinear, bicubic, biquintic and bicubic spline interpolants respectively (Vax 11/750 fpa).
shiftlines, magnify, rotate, geomap, geotran, imlintran,