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+.help imlintran Dec98 images.imgeom
+.ih
+NAME
+imlintran -- shift, scale, rotate a list of images
+.ih
+USAGE
+imlintran input output xrotation yrotation xmag ymag
+.ih
+PARAMETERS
+.ls input
+List of images to be transformed.
+.le
+.ls output
+List of output images.
+.le
+.ls 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 introduced by
+making the angle between xrotation and yrotation other than a
+multiple of 90 degrees.
+.le
+.ls xmag, ymag
+The number of input pixels per output 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.
+.le
+.ls xin = INDEF, yin = INDEF
+The origin of the input picture in pixels. Xin and yin default to the center of
+the input image.
+.le
+.ls xout = INDEF, yout = INDEF
+The origin of the output image. Xout and yout default to the center of the
+output image.
+.le
+.ls ncols = INDEF, nlines = INDEF
+The number of columns and rows 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.
+.le
+.ls interpolant = "linear"
+The choices are the following.
+.ls nearest
+Nearest neighbor.
+.le
+.ls linear
+Bilinear interpolation in x and y.
+.le
+.ls poly3
+Third order interior polynomial in x and y.
+.le
+.ls poly5
+Fifth order interior polynomial in x and y.
+.le
+.ls spline3
+Bicubic spline.
+.le
+.ls sinc
+2D sinc interpolation. Users can specify the sinc interpolant width by
+appending a width value to the interpolant string, e.g. sinc51 specifies
+a 51 by 51 pixel wide sinc interpolant. The sinc width will be rounded up to
+the nearest odd number.  The default sinc width is 31 by 31.
+.le
+.ls lsinc
+Look-up table sinc interpolation. Users can specify the look-up table sinc
+interpolant width by appending a width value to the interpolant string, e.g.
+lsinc51 specifies a 51 by 51 pixel wide look-up table sinc interpolant. The user
+supplied sinc width will be rounded up to the nearest odd number. The default
+sinc width is 31 by 31 pixels. Users can specify the resolution of the lookup
+table sinc by appending the look-up table size in square brackets to the
+interpolant string, e.g. lsinc51[20] specifies a 20 by 20 element sinc
+look-up table interpolant with a pixel resolution of 0.05 pixels in x and y.
+The default look-up table size and resolution are 20 by 20 and 0.05 pixels
+in x and y respectively.
+.le
+.ls drizzle
+2D drizzle resampling. Users can specify the drizzle pixel fraction in x and y
+by appending a value between 0.0 and 1.0 in square brackets to the
+interpolant string, e.g. drizzle[0.5]. The default value is 1.0.
+The value 0.0 is increased internally to 0.001. Drizzle resampling
+with a pixel fraction of 1.0 in x and y is equivalent to fractional pixel
+rotated block summing (fluxconserve = yes) or averaging (flux_conserve = no)  if
+xmag and ymag are > 1.0.
+.le
+.le
+.ls boundary = "nearest"
+The choices are:
+.ls nearest
+Use the value of the nearest boundary pixel.
+.le
+.ls constant
+Use a constant value.
+.le
+.ls reflect
+Generate value by reflecting about the boundary.
+.le
+.ls wrap
+Generate a value by wrapping around to the opposite side of the image.
+.le
+.le
+.ls constant = 0.
+The value of the constant for boundary extension.
+.le
+.ls fluxconserve = yes
+Preserve the total image flux?
+.le
+.ls nxblock = 512, nyblock = 512
+If the size of the output image is less than nxblock by nyblock then
+the entire image is transformed at once. Otherwise the output image
+is computed in blocks of nxblock by nxblock pixels.
+.le
+.ih
+DESCRIPTION
+
+IMLINTRAN linearly transforms a the list of images in input using rotation
+angles and magnification factors supplied by the user and writes the output
+images into output. The coordinate transformation from input to output
+image is described below.
+
+.nf
+    1. subtract the origin
+
+    xt = x(input) - xin
+    yt = y(input) - yin
+
+    2. scale the image
+
+    xt = xt / xmag
+    yt = xt / xmag
+
+    3. rotate the image
+
+    xt = xt * cos (xrotation) - yt * sin (yrotation)
+    yt = xt * sin (yrotation) + yt * cos (yrotation)
+
+    4. new orgin
+
+    x(output) = xt + xout
+    y(output) = yt + yout
+
+.fi
+
+The output image gray levels are determined by interpolating in the input
+image at the positions of the transformed output pixels using the inverse
+of the above transformation.
+IMLINTRAN uses the routines in the 2-D interpolation package.
+
+.ih
+TIMINGS
+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).
+
+.ih
+EXAMPLES
+
+.nf
+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 scale in x and y
+   by a factor of 1.5
+
+   cl> imlintran n7026 n7026rm 45.0 45.0 1.5 1.5
+.fi
+
+.ih
+BUGS
+.ih
+SEE ALSO
+imshift, magnify, rotate, lintran, register, geotran, geomap
+.endhelp