1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
|
#! /usr/bin/env python
"""Simple test script for imgfile.c
Roger E. Masse
"""
from test_support import verbose
import imgfile
def main():
# Test a 3 byte color image
testimage('test.rgb')
# Test a 1 byte greyscale image
testimage('greytest.rgb')
def testimage(name):
"""Run through the imgfile's battery of possible methods
on the image passed in name.
"""
import sys
import os
import string
outputfile = '/tmp/deleteme'
# try opening the name directly
try:
# This function returns a tuple (x, y, z) where x and y are the size
# of the image in pixels and z is the number of bytes per pixel. Only
# 3 byte RGB pixels and 1 byte greyscale pixels are supported.
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))
# This function reads and decodes the image on the specified file,
# and returns it as a python string. The string has either 1 byte
# greyscale pixels or 4 byte RGBA pixels. The bottom left pixel
# is the first in the string. This format is suitable to pass
# to gl.lrectwrite, for instance.
image = imgfile.read(name)
# This function writes the RGB or greyscale data in data to
# image file file. x and y give the size of the image, z is
# 1 for 1 byte greyscale images or 3 for RGB images (which
# are stored as 4 byte values of which only the lower three
# bytes are used). These are the formats returned by gl.lrectread.
if verbose:
print 'Writing output file'
imgfile.write (outputfile, image, sizes[0], sizes[1], sizes[2])
if verbose:
print 'Opening scaled test image: %s, sizes: %s' % (name, str(sizes))
# This function is identical to read but it returns an image that
# is scaled to the given x and y sizes. If the filter and blur
# parameters are omitted scaling is done by simply dropping
# or duplicating pixels, so the result will be less than perfect,
# especially for computer-generated images. Alternatively,
# you can specify a filter to use to smoothen the image after
# scaling. The filter forms supported are 'impulse', 'box',
# 'triangle', 'quadratic' and 'gaussian'. If a filter is
# specified blur is an optional parameter specifying the
# blurriness of the filter. It defaults to 1.0. readscaled
# makes no attempt to keep the aspect ratio correct, so that
# is the users' responsibility.
if verbose:
print 'Filtering with "impulse"'
simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'impulse', 2.0)
# This function sets a global flag which defines whether the
# scan lines of the image are read or written from bottom to
# top (flag is zero, compatible with SGI GL) or from top to
# bottom(flag is one, compatible with X). The default is zero.
if verbose:
print 'Switching to X compatibility'
imgfile.ttob (1)
if verbose:
print 'Filtering with "triangle"'
simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'triangle', 3.0)
if verbose:
print 'Switching back to SGI compatibility'
imgfile.ttob (0)
if verbose: print 'Filtering with "quadratic"'
simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'quadratic')
if verbose: print 'Filtering with "gaussian"'
simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'gaussian', 1.0)
if verbose:
print 'Writing output file'
imgfile.write (outputfile, simage, sizes[0]/2, sizes[1]/2, sizes[2])
os.unlink(outputfile)
main()
|
