Lib/test/test_imageop.py

   1 #! /usr/bin/env python
   2
   3 """Test script for the imageop module.  This has the side
   4    effect of partially testing the imgfile module as well.
   5    Roger E. Masse
   6 """
   7
   8 from test.test_support import verbose, unlink
   9
  10 import imageop, uu, os
  11
  12 def main(use_rgbimg=1):
  13
  14     # Create binary test files
  15     uu.decode(get_qualified_path('testrgb'+os.extsep+'uue'), 'test'+os.extsep+'rgb')
  16
  17     if use_rgbimg:
  18         image, width, height = getrgbimage('test'+os.extsep+'rgb')
  19     else:
  20         image, width, height = getimage('test'+os.extsep+'rgb')
  21
  22     # Return the selected part of image, which should by width by height
  23     # in size and consist of pixels of psize bytes.
  24     if verbose:
  25         print 'crop'
  26     newimage = imageop.crop (image, 4, width, height, 0, 0, 1, 1)
  27
  28     # Return image scaled to size newwidth by newheight. No interpolation
  29     # is done, scaling is done by simple-minded pixel duplication or removal.
  30     # Therefore, computer-generated images or dithered images will
  31     # not look nice after scaling.
  32     if verbose:
  33         print 'scale'
  34     scaleimage = imageop.scale(image, 4, width, height, 1, 1)
  35
  36     # Run a vertical low-pass filter over an image. It does so by computing
  37     # each destination pixel as the average of two vertically-aligned source
  38     # pixels. The main use of this routine is to forestall excessive flicker
  39     # if the image two vertically-aligned source pixels,  hence the name.
  40     if verbose:
  41         print 'tovideo'
  42     videoimage = imageop.tovideo (image, 4, width, height)
  43
  44     # Convert an rgb image to an 8 bit rgb
  45     if verbose:
  46         print 'rgb2rgb8'
  47     greyimage = imageop.rgb2rgb8(image, width, height)
  48
  49     # Convert an 8 bit rgb image to a 24 bit rgb image
  50     if verbose:
  51         print 'rgb82rgb'
  52     image = imageop.rgb82rgb(greyimage, width, height)
  53
  54     # Convert an rgb image to an 8 bit greyscale image
  55     if verbose:
  56         print 'rgb2grey'
  57     greyimage = imageop.rgb2grey(image, width, height)
  58
  59     # Convert an 8 bit greyscale image to a 24 bit rgb image
  60     if verbose:
  61         print 'grey2rgb'
  62     image = imageop.grey2rgb(greyimage, width, height)
  63
  64     # Convert a 8-bit deep greyscale image to a 1-bit deep image by
  65     # thresholding all the pixels. The resulting image is tightly packed
  66     # and is probably only useful as an argument to mono2grey.
  67     if verbose:
  68         print 'grey2mono'
  69     monoimage = imageop.grey2mono (greyimage, width, height, 0)
  70
  71     # monoimage, width, height = getimage('monotest.rgb')
  72     # Convert a 1-bit monochrome image to an 8 bit greyscale or color image.
  73     # All pixels that are zero-valued on input get value p0 on output and
  74     # all one-value input pixels get value p1 on output. To convert a
  75     # monochrome  black-and-white image to greyscale pass the values 0 and
  76     # 255 respectively.
  77     if verbose:
  78         print 'mono2grey'
  79     greyimage = imageop.mono2grey (monoimage, width, height, 0, 255)
  80
  81     # Convert an 8-bit greyscale image to a 1-bit monochrome image using a
  82     # (simple-minded) dithering algorithm.
  83     if verbose:
  84         print 'dither2mono'
  85     monoimage = imageop.dither2mono (greyimage, width, height)
  86
  87     # Convert an 8-bit greyscale image to a 4-bit greyscale image without
  88     # dithering.
  89     if verbose:
  90         print 'grey2grey4'
  91     grey4image = imageop.grey2grey4 (greyimage, width, height)
  92
  93     # Convert an 8-bit greyscale image to a 2-bit greyscale image without
  94     # dithering.
  95     if verbose:
  96         print 'grey2grey2'
  97     grey2image = imageop.grey2grey2 (greyimage, width, height)
  98
  99     # Convert an 8-bit greyscale image to a 2-bit greyscale image with
 100     # dithering. As for dither2mono, the dithering algorithm is currently
 101     # very simple.
 102     if verbose:
 103         print 'dither2grey2'
 104     grey2image = imageop.dither2grey2 (greyimage, width, height)
 105
 106     # Convert a 4-bit greyscale image to an 8-bit greyscale image.
 107     if verbose:
 108         print 'grey42grey'
 109     greyimage = imageop.grey42grey (grey4image, width, height)
 110
 111     # Convert a 2-bit greyscale image to an 8-bit greyscale image.
 112     if verbose:
 113         print 'grey22grey'
 114     image = imageop.grey22grey (grey2image, width, height)
 115
 116     # Cleanup
 117     unlink('test'+os.extsep+'rgb')
 118
 119 def getrgbimage(name):
 120     """return a tuple consisting of image (in 'imgfile' format but
 121     using rgbimg instead) width and height"""
 122
 123     import rgbimg
 124
 125     try:
 126         sizes = rgbimg.sizeofimage(name)
 127     except rgbimg.error:
 128         name = get_qualified_path(name)
 129         sizes = rgbimg.sizeofimage(name)
 130     if verbose:
 131         print 'rgbimg opening test image: %s, sizes: %s' % (name, str(sizes))
 132
 133     image = rgbimg.longimagedata(name)
 134     return (image, sizes[0], sizes[1])
 135
 136 def getimage(name):
 137     """return a tuple consisting of
 138        image (in 'imgfile' format) width and height
 139     """
 140
 141     import imgfile
 142
 143     try:
 144         sizes = imgfile.getsizes(name)
 145     except imgfile.error:
 146         name = get_qualified_path(name)
 147         sizes = imgfile.getsizes(name)
 148     if verbose:
 149         print 'imgfile opening test image: %s, sizes: %s' % (name, str(sizes))
 150
 151     image = imgfile.read(name)
 152     return (image, sizes[0], sizes[1])
 153
 154 def get_qualified_path(name):
 155     """ return a more qualified path to name"""
 156     import sys
 157     import os
 158     path = sys.path
 159     try:
 160         path = [os.path.dirname(__file__)] + path
 161     except NameError:
 162         pass
 163     for dir in path:
 164         fullname = os.path.join(dir, name)
 165         if os.path.exists(fullname):
 166             return fullname
 167     return name
 168
 169 # rgbimg (unlike imgfile) is portable to platforms other than SGI.
 170 # So we prefer to use it.
 171 main(use_rgbimg=1)