libvips/python/example/cod.py

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#!/usr/bin/python
import sys
import logging
#logging.basicConfig(level = logging.DEBUG)
import gi
gi.require_version('Vips', '8.0')
from gi.repository import Vips
#Vips.cache_set_trace(True)
def to_polar(image):
"""Transform image coordinates to polar.
The image is transformed so that it is wrapped around a point in the
centre. Vertical straight lines become circles or segments of circles,
horizontal straight lines become radial spokes.
"""
# xy image, origin in the centre, scaled to fit image to a circle
xy = Vips.Image.xyz(image.width, image.height)
xy -= [image.width / 2.0, image.height / 2.0]
scale = min(image.width, image.height) / float(image.width)
xy *= 2.0 / scale
index = xy.polar()
# scale vertical axis to 360 degrees
index *= [1, image.height / 360.0]
return image.mapim(index)
def to_rectangular(image):
"""Transform image coordinates to rectangular.
The image is transformed so that it is unwrapped from a point in the
centre. Circles or segments of circles become vertical straight lines,
radial lines become horizontal lines.
"""
# xy image, vertical scaled to 360 degrees
xy = Vips.Image.xyz(image.width, image.height)
xy *= [1, 360.0 / image.height]
index = xy.rect()
# scale to image rect
scale = min(image.width, image.height) / float(image.width)
index *= scale / 2.0
index += [image.width / 2.0, image.height / 2.0]
return image.mapim(index)
a = Vips.Image.new_from_file(sys.argv[1])
a = to_polar(a)
a = to_rectangular(a)
a.write_to_file(sys.argv[2])