Class: RemoveWhiteBorder::Remover

Inherits:
Object
  • Object
show all
Defined in:
lib/remove_white_border.rb

Constant Summary collapse

WHITE = 
60000

Instance Method Summary collapse

Constructor Details

#initialize(filename) ⇒ Remover

Returns a new instance of Remover.



9
10
11
12
13
14
 
# File 'lib/remove_white_border.rb', line 9

def initialize(filename)
  @filename = filename
  @image    = Magick::Image.read(filename).first
  @width    = @image.columns
  @height   = @image.rows
end

Instance Method Details

#calculate_center(x = nil, y = nil, width = nil, height = nil) ⇒ Object

Determines and x and y that should be good to use for scanning the image.



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
 
# File 'lib/remove_white_border.rb', line 28

def calculate_center(x = nil, y = nil, width = nil, height = nil)
  x      ||= @width / 2
  y      ||= @height / 2
  width  ||= @width
  height ||= @height

  return @coords if @coords
  return (@coords = [x, y]) if !white?(x, y)
  return if width <= 2 || height <= 2

  if coords = calculate_center(x - width/2, y - height/2, width/2, height/2)
    return coords
  end

  if coords = calculate_center(x - width/2, y + height/2, width/2, height/2)
    return coords
  end

  if coords = calculate_center(x + width/2, y - height/2, width/2, height/2)
    return coords
  end

  if coords = calculate_center(x + width/2, y + height/2, width/2, height/2)
    return coords
  end
end

#nonwhite_bottom ⇒ Object 



69
70
71
72
73
74
75
76
77
78
79
80
81
 
# File 'lib/remove_white_border.rb', line 69

def nonwhite_bottom
  # Find a good x to use.
  x0 = calculate_center[0]

  # Start with a quick scan up to find the first y that is not white.
  y = @height - 1
  y -= 1 while (y > 0) && white?(x0, y)

  # Now move back down until we find a row that is all white.
  y += 1 while (y < @height - 1) && !white?(nil, y)

  return y
end

#nonwhite_left ⇒ Object 



83
84
85
86
87
88
89
90
91
92
93
94
95
 
# File 'lib/remove_white_border.rb', line 83

def nonwhite_left
  # Find a good y to use.
  y0 = calculate_center[1]

  # Start with a quick scan right to find the first x that is not white.
  x = 0
  x += 1 while (x < @width - 1) && white?(x, y0)

  # Now move back left until we find a column that is all white.
  x -= 1 while (x > 0) && !white?(x, nil)

  return x
end

#nonwhite_right ⇒ Object 



97
98
99
100
101
102
103
104
105
106
107
108
109
 
# File 'lib/remove_white_border.rb', line 97

def nonwhite_right
  # Find a good y to use.
  y0 = calculate_center[1]

  # Start with a quick scan left to find the first x that is not white.
  x = @width - 1
  x -= 1 while (x > 0) && white?(x, y0)

  # Now move back right until we find a column that is all white.
  x += 1 while (x < @width - 1) && !white?(x, nil)

  return x
end

#nonwhite_top ⇒ Object 



55
56
57
58
59
60
61
62
63
64
65
66
67
 
# File 'lib/remove_white_border.rb', line 55

def nonwhite_top
  # Find a good x to use.
  x0 = calculate_center[0]

  # Start with a quick scan down to find the first y that is not white.
  y = 0
  y += 1 while (y < @height - 1) && white?(x0, y)

  # Now move back up until we find a row that is all white.
  y -= 1 while (y > 0) && !white?(nil, y)

  return y
end

#white?(x, y) ⇒ Boolean

Returns:

  • (Boolean) 


16
17
18
19
20
21
22
23
24
25
 
# File 'lib/remove_white_border.rb', line 16

def white?(x, y)
  if x && y
    p = @image.pixel_color(x, y)
    %w( red green blue ).all? { |c| p.send(c) >= WHITE }
  elsif x
    (0 ... @height).all? { |y| white? x, y }
  elsif y
    (0 ... @width).all? { |x| white? x, y }
  end
end

#write(output = nil) ⇒ Object 



111
112
113
114
115
116
117
118
119
120
 
# File 'lib/remove_white_border.rb', line 111

def write(output = nil)
  output ||= @filename

  x      = nonwhite_left
  y      = nonwhite_top
  width  = nonwhite_right - x
  height = nonwhite_bottom - y

  @image.crop(x, y, width, height).write(output)
end