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comparison transformations/contrast.py @ 27:0b9350998dbe

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Added a contrast.py script difining the Contrast transformation class
author Xavier Glorot <glorotxa@iro.umontreal.ca>
date Fri, 29 Jan 2010 14:10:10 -0500
parents
children 7ef8aac2cdb5
comparison
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26:47e7202d4f19 27:0b9350998dbe
1 #!/usr/bin/python
2 # coding: utf-8
3
4 '''
5 Simple implementation of random contrast. This always switch half the time the polarity.
6 then it decide of a bias and of a contrast, both of them are dependant of the complexity.
7
8 Author: Xavier Glorot
9 '''
10
11 import scipy.ndimage.morphology
12 import numpy as N
13 import copy
14
15
16 class Contrast():
17 def __init__(self,complexity = 1):
18 #---------- private attributes
19 self.__nx__ = 32 #xdim of the images
20 self.__ny__ = 32 #ydim of the images
21 self.__Pinvert__ = 0.5 #probability to switch polarity
22 self.__mincontrast__ = 0.15
23 self.__resolution__ = 256
24 self.__rangecontrastres__ = self.__resolution__ - N.int(self.__mincontrast__*self.__resolution__)
25 #------------------------------------------------
26
27 #---------- generation parameters
28 self.regenerate_parameters(complexity)
29 #------------------------------------------------
30
31 def _get_current_parameters(self):
32 return [self.invert,self.contrast]
33
34 def get_settings_names(self):
35 return ['invert','contrast']
36
37 def regenerate_parameters(self, complexity):
38 self.invert = (N.random.uniform() < self.__Pinvert__)
39 self.contrast = self.__resolution__ - N.random.randint(1 + self.__rangecontrastres__ * complexity)
40 return self._get_current_parameters()
41
42 def transform_1_image(self,image): #the real transformation method
43 maxi = image.max()
44 mini = image.min()
45 if self.invert:
46 newimage = 1 - (self.__resolution__- self.contrast) / (2 * float(self.__resolution__)) -\
47 (image - mini) / float(maxi - mini) * self.contrast / float(self.__resolution__)
48 else:
49 newimage = (self.__resolution__- self.contrast) / (2 * float(self.__resolution__)) +\
50 (image - mini) / float(maxi - mini) * self.contrast / float(self.__resolution__)
51 if image.dtype == 'uint8':
52 return N.asarray(newimage*255,dtype='uint8')
53 else:
54 return N.asarray(newimage,dtype=image.dtype)
55
56 def transform_image(self,image): #handling different format
57 if image.shape == (self.__nx__,self.__ny__):
58 return self.transform_1_image(image)
59 if image.ndim == 3:
60 newimage = copy.copy(image)
61 for i in range(image.shape[0]):
62 newimage[i,:,:] = self.transform_1_image(image[i,:,:])
63 return newimage
64 if image.ndim == 2 and image.shape != (self.__nx__,self.__ny__):
65 newimage = N.reshape(image,(image.shape[0],self.__nx__,self.__ny__))
66 for i in range(image.shape[0]):
67 newimage[i,:,:] = self.transform_1_image(newimage[i,:,:])
68 return N.reshape(newimage,image.shape)
69 if image.ndim == 1:
70 newimage = N.reshape(image,(self.__nx__,self.__ny__))
71 newimage = self.transform_1_image(newimage)
72 return N.reshape(newimage,image.shape)
73 assert False #should never go there
74
75
76
77
78 #test on NIST (you need pylearn and access to NIST to do that)
79
80 if __name__ == '__main__':
81
82 from pylearn.io import filetensor as ft
83 import copy
84 import pygame
85 import time
86 datapath = '/data/lisa/data/nist/by_class/'
87 f = open(datapath+'digits/digits_train_data.ft')
88 d = ft.read(f)
89
90 pygame.surfarray.use_arraytype('numpy')
91
92 pygame.display.init()
93 screen = pygame.display.set_mode((8*2*32,8*32),0,8)
94 anglcolorpalette=[(x,x,x) for x in xrange(0,256)]
95 screen.set_palette(anglcolorpalette)
96
97 MyContrast = Contrast()
98
99 debut=time.time()
100 MyContrast.transform_image(d)
101 fin=time.time()
102 print '------------------------------------------------'
103 print d.shape[0],' images transformed in :', fin-debut, ' seconds'
104 print '------------------------------------------------'
105 print (fin-debut)/d.shape[0]*1000000,' microseconds per image'
106 print '------------------------------------------------'
107 print MyContrast.get_settings_names()
108 print MyContrast._get_current_parameters()
109 print MyContrast.regenerate_parameters(0)
110 print MyContrast.regenerate_parameters(0.5)
111 print MyContrast.regenerate_parameters(1)
112 for i in range(10000):
113 a=d[i,:]
114 b=N.asarray(N.reshape(a,(32,32))).T
115
116 new=pygame.surfarray.make_surface(b)
117 new=pygame.transform.scale2x(new)
118 new=pygame.transform.scale2x(new)
119 new=pygame.transform.scale2x(new)
120 new.set_palette(anglcolorpalette)
121 screen.blit(new,(0,0))
122
123 print MyContrast.get_settings_names(), MyContrast.regenerate_parameters(1)
124 c=MyContrast.transform_image(a)
125 b=N.asarray(N.reshape(c,(32,32))).T
126
127 new=pygame.surfarray.make_surface(b)
128 new=pygame.transform.scale2x(new)
129 new=pygame.transform.scale2x(new)
130 new=pygame.transform.scale2x(new)
131 new.set_palette(anglcolorpalette)
132 screen.blit(new,(8*32,0))
133
134 pygame.display.update()
135 raw_input('Press Enter')
136
137 pygame.display.quit()