up [pdf]
from rsf.proj import *

# Download data
Fetch('slice.rsf','ctscan')
Flow('circle','slice','dd type=float')

grey = 'grey wanttitle=n screenratio=1 bias=128 clip=105'

Result('circle',grey)

# Rotate program
program = Program('rotate.c')

# COMMENT ABOVE AND UNCOMMENT BELOW IF YOU WANT TO USE PYTHON 
# program = Command('rotate.exe','rotate.py','cp $SOURCE $TARGET')
# AddPostAction(program,Chmod(program,0o755))

rotate = str(program[0])

# Rotate by 90 degrees
Flow('rotate',['circle',rotate],
     './${SOURCES[1]} angle=90 interp=nearest')

Result('rotate',grey)

# Mask for the circle
Flow('mask','circle',
     '''
     put d1=1 o1=-255.5 d2=1 o2=-255.5 |
     math output="sqrt(x1*x1+x2*x2)" |
     mask min=255.5 | dd type=float | 
     smooth rect1=3 rect2=3 |
     mask max=0 | dd type=float |
     put d1=0.1914 o1=0 d2=0.1914 o2=0
     ''')

for case in ('nearest','linear'): # !!! MODIFY ME !!!
    new = 'circle'
    rotates = []
    for r in range(18):
        old = new
        new = '%s-circle%d' % (case,r)
        Flow(new,[old,rotate],
             './${SOURCES[1]} angle=20 interp=%s' % case)
        Plot(new,grey)
        rotates.append(new)

    # Movie of rotating circle
    Plot(case,rotates,'Movie',view=1)

    # Plot error
    Result(case,[new,'circle','mask'],
           '''
           add scale=1,-1 ${SOURCES[1]} |
           add mode=p ${SOURCES[2]} |
           %s bias=0 scalebar=y clip=12
           wanttitle=y title="Error of %s Interpolation"
           ''' % (grey,case.capitalize()))

End()

sfdd
sfgrey
sfput
sfmath
sfmask
sfsmooth
sfadd

data/ctscan/slice.rsf