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#! /usr/bin/env python
"""Test script for the imageop module. This has the side
effect of partially testing the imgfile module as well.
Roger E. Masse
"""
from test_support import verbose
import imageop
def main():
image, width, height = getimage('test.rgb')
# Return the selected part of image, which should by width by height
# in size and consist of pixels of psize bytes.
if verbose:
print 'crop'
newimage = imageop.crop (image, 4, width, height, 0, 0, 1, 1)
# Return image scaled to size newwidth by newheight. No interpolation
# is done, scaling is done by simple-minded pixel duplication or removal.
# Therefore, computer-generated images or dithered images will
# not look nice after scaling.
if verbose:
print 'scale'
scaleimage = imageop.scale(image, 4, width, height, 1, 1)
# Run a vertical low-pass filter over an image. It does so by computing
# each destination pixel as the average of two vertically-aligned source
# pixels. The main use of this routine is to forestall excessive flicker
# if the image two vertically-aligned source pixels, hence the name.
if verbose:
print 'tovideo'
videoimage = imageop.tovideo (image, 4, width, height)
image, width, height = getimage('greytest.rgb')
# Convert a 8-bit deep greyscale image to a 1-bit deep image by
# tresholding all the pixels. The resulting image is tightly packed
# and is probably only useful as an argument to mono2grey.
if verbose:
print 'grey2mono'
monoimage = imageop.grey2mono (image, width, height, 0)
#monoimage, width, height = getimage('monotest.rgb')
# Convert a 1-bit monochrome image to an 8 bit greyscale or color image.
# All pixels that are zero-valued on input get value p0 on output and
# all one-value input pixels get value p1 on output. To convert a
# monochrome black-and-white image to greyscale pass the values 0 and
# 255 respectively.
if verbose:
print 'mono2grey'
greyimage = imageop.mono2grey (monoimage, width, height, 0, 255)
# Convert an 8-bit greyscale image to a 1-bit monochrome image using a
# (simple-minded) dithering algorithm.
if verbose:
print 'dither2mono'
monoimage = imageop.dither2mono (greyimage, width, height)
# Convert an 8-bit greyscale image to a 4-bit greyscale image without
# dithering.
if verbose:
print 'grey2grey4'
grey4image = imageop.grey2grey4 (greyimage, width, height)
# Convert an 8-bit greyscale image to a 2-bit greyscale image without
# dithering.
if verbose:
print 'grey2grey2'
grey2image = imageop.grey2grey2 (greyimage, width, height)
# Convert an 8-bit greyscale image to a 2-bit greyscale image with
# dithering. As for dither2mono, the dithering algorithm is currently
# very simple.
if verbose:
print 'dither2grey2'
grey2image = imageop.dither2grey2 (greyimage, width, height)
# Convert a 4-bit greyscale image to an 8-bit greyscale image.
if verbose:
print 'grey42grey'
greyimage = imageop.grey42grey (grey4image, width, height)
# Convert a 2-bit greyscale image to an 8-bit greyscale image.
if verbose:
print 'grey22grey'
image = imageop.grey22grey (grey2image, width, height)
def getimage(name):
"""return a tuple consisting of
image (in 'imgfile' format) width and height
"""
import sys
import os
import imgfile
import string
# try opening the name directly
try:
sizes = imgfile.getsizes(name)
except imgfile.error:
# get a more qualified path component of the script...
if __name__ == '__main__':
ourname = sys.argv[0]
else: # ...or the full path of the module
ourname = sys.modules[__name__].__file__
parts = string.splitfields(ourname, os.sep)
parts[-1] = name
name = string.joinfields(parts, os.sep)
sizes = imgfile.getsizes(name)
if verbose:
print 'Opening test image: %s, sizes: %s' % (name, str(sizes))
image = imgfile.read(name)
return (image, sizes[0], sizes[1])
main()
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