imlintran input output xrotation yrotation xmag ymag
input
List of images to be transformed.
output
List of output images.
xrotation, yrotation
Angle of rotation of points on the image axes in degrees.
Positive angles rotate in a counter-clockwise sense around the x axis.
For a normal coordinate axes rotation xrotation and yrotation should
be the same. A simple y axis flip can be introduced by make yrotation
equal to xrotation plus 180 degrees. An axis skew can be intoduced by
making the angle between xrotation and yrotation other than a
multiple of 90 degrees.
xmag, ymag
The number of output pixels per input pixel in x and y. The magnifications
must always be positive numbers. Numbers less than 1 magnify the image;
numbers greater than one reduce the image.
xin = INDEF, yin = INDEF
The origin of the input picture in pixels. Xin and yin default to the center of
the input image.
xout = INDEF, yout = INDEF
The origin of the output image. Xout and yout default to the center of the
output image.
ncols = INDEF, nlines = INDEF
The number of columns and rowsx in the output image. The default is to
keep the dimensions the same as the input image. If ncols and nrows are
less than or equal to zero then the task computes the number of rows and
columns required to include the whole input image, excluding the effects
of any origin shift.
interpolant = 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 = 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.
constant = 0.
The value of the constant for boundary extension.
fluxconserve = yes
Preserve the total image flux?
IMLINTRAN linearly transforms a the list of images in input using rotatiion angles and magnification factors supplied by the user and writes the output images into output. The coordinate transformation is described below.
1. subtract the origin
xt = x - xin
yt = y - yin
2. scale the image
xt = xmag * xt + ymag * yt
yt = xmag * xt + ymag * yt
3. rotate the image
xt = xt * cos (xrotation) - yt * sin (yrotation)
yt = xt * sin (yrotation) + yt * cos (yrotation)
4. new orgin
xt = x + xout
yt = y + yout
The output image gray levels are determined by interpolating in the input image at the positions of the transformed output pixels. IMLINTRAN uses the routines in the 2-D interpolation package.
It requires approximately 70 and 290 cpu seconds respectively to linearly transform a 512 by 512 real image using bilinear and biquintic interpolation respectively (Vax 11/750 fpa).
1. Rotate an image 45 degrees around its center and magnify the image by a factor of 2. in each direction. cl> imlintran n4151 n4151rm 45.0 45.0 0.50 0.50 2. Rotate the axes of an image by 45 degrees around 100. and 100., shift the orgin to 150. and 150. and flip the y axis. cl> imlintran n1068 n1068r 45.0 225.0 1.0 1.0 xin=100. yin=100. >>> xout=150. yout=150. 3. Rotate an image by 45 degrees and reduce the the scale in x and y by a factor of 1.5 cl> imlintran n7026 n7026rm 45.0 45.0 1.5 1.5
imshift, magnify, rotate, lintran, register, geotran, geomap,