Package image

Contains some utility methods for handling images. More...


Functions

def int_sequence
 Converts a sequence of floats (ranged 0 to 1) to integers (ranged 0 to 155).
def float_sequence
 Converts a sequence of integers (ranged 0 to 255) to floats (ranged 0 to 1).
def grid_to_rgb_image
 Converts a 2D grid to an image on the disk.
def rgb_image_to_image_grid_channels
 Loads an image from disk, and returns a tuplet of grids, one for each channel.
def channels_to_rgb_grid
 Converts a list of three grids into an RGB grid.
def rgb_image_to_grid
 Loads an image from disk into a grid.
def index_grid_to_rgb_grid
 Take a grid containing non-negative integers, and makes a new grid with elements from the pallet.
def transpose
def greyscale_grid_to_rgb_grid
 Converts a greyscale grid (every cell contains a float [0.
def rgb_grid_to_greyscale_grid
def edge
 An extremely simple edge detection algorithm.
def normalize
 Returns a grid in which the colours have been normalised.
def normalize_grey
 Returns a grid where all values have been normalised between 0 and 1.
def saturate
 Clamps all values in a grid between 0 and 1.
def threshold
def multiply_grid
 Multiplies all values of a grid with a constant.
def add_grid
 Adss a constant to all values of a grid.
def entropy
 Returns a grid that represents the entropy around the pixels in a given grid.
def white_noise
 Returns a grid containing white noise in the range [0 1].
def mix_grey
 Interpolates a grey between two given greys.
def mix_color
 Interpolates a color between two given colors.
def tile
 Returns a new grid, containing m by n copies of the given grid.
def add_grey_grids
 Adds weighted values of grids together.
def integrate
 Calculates the integral grid of a grid.
def integrate_vertically
def blend


Detailed Description

Contains some utility methods for handling images.


Function Documentation

def image.add_grey_grids (   grids,
  factors = None 
)

Adds weighted values of grids together.

Definition at line 316 of file image.py.

def image.add_grid (   grid,
  summand 
)

Adss a constant to all values of a grid.

Returns the result as a new grid.

Definition at line 229 of file image.py.

def image.blend (   grid1,
  grid2,
  blend_image 
)

Definition at line 359 of file image.py.

def image.channels_to_rgb_grid (   grids  ) 

Converts a list of three grids into an RGB grid.

The three grids each represents a color channel, and should contain floating point values between 0 and 1. The resulting grid contains tuples, each with four elements, between 0 and 1, representing RGBA. Alpha is laways set to 1.

Definition at line 61 of file image.py.

def image.edge (   grid  ) 

An extremely simple edge detection algorithm.

Definition at line 128 of file image.py.

def image.entropy (   grid,
  n 
)

Returns a grid that represents the entropy around the pixels in a given grid.

The entropy around a pixel is measured as the sum of the absolute differences between that pixel's channels and the surrounding pixels' corresponding channels.

Parameters:
grid The grid to measure
n Determines the size of the window around eaxh pixel to use. If n is 1, the window size is 3by3, if it is 2, the window size is 5 by 5.

Definition at line 245 of file image.py.

def image.float_sequence (   seq  ) 

Converts a sequence of integers (ranged 0 to 255) to floats (ranged 0 to 1).

Definition at line 22 of file image.py.

def image.greyscale_grid_to_rgb_grid (   grid,
  color 
)

Converts a greyscale grid (every cell contains a float [0.

.1]) into an RGB grid. The given color is multiplied by the value in the grid to give the value of the corresponding cell in the new grid.

Definition at line 108 of file image.py.

def image.grid_to_rgb_image (   grid,
  fname 
)

Converts a 2D grid to an image on the disk.

The grid must contain float values (ranged 0 to 1).

Definition at line 32 of file image.py.

def image.index_grid_to_rgb_grid (   grid,
  pallet 
)

Take a grid containing non-negative integers, and makes a new grid with elements from the pallet.

If the old grid had an element 3 in a cell, then the element in the corresponding cell in the new grid will hold the value of the 4th element of the pallet.

Definition at line 87 of file image.py.

def image.int_sequence (   seq  ) 

Converts a sequence of floats (ranged 0 to 1) to integers (ranged 0 to 155).

Definition at line 13 of file image.py.

def image.integrate (   grid  ) 

Calculates the integral grid of a grid.

Definition at line 329 of file image.py.

def image.integrate_vertically (   grid  ) 

Definition at line 346 of file image.py.

def image.mix_color (   color0,
  color1,
  t 
)

Interpolates a color between two given colors.

If t is set to 0, the returned grey is the same as col1. If t is set to 1, the returned grey is the same as col2.

Definition at line 293 of file image.py.

def image.mix_grey (   col1,
  col2,
  t 
)

Interpolates a grey between two given greys.

If t is set to 0, the returned grey is the same as col1. If t is set to 1, the returned grey is the same as col2.

Definition at line 286 of file image.py.

def image.multiply_grid (   grid,
  factor 
)

Multiplies all values of a grid with a constant.

Returns the result as a new grid.

Definition at line 220 of file image.py.

def image.normalize (   grid  ) 

Returns a grid in which the colours have been normalised.

Colours are adjusted so that the returned grid has a minimum color component of 0, and a maximum component of 1.

Definition at line 151 of file image.py.

def image.normalize_grey (   grid  ) 

Returns a grid where all values have been normalised between 0 and 1.

Definition at line 180 of file image.py.

def image.rgb_grid_to_greyscale_grid (   grid  ) 

Definition at line 118 of file image.py.

def image.rgb_image_to_grid (   fname  ) 

Loads an image from disk into a grid.

Definition at line 72 of file image.py.

def image.rgb_image_to_image_grid_channels (   fname  ) 

Loads an image from disk, and returns a tuplet of grids, one for each channel.

The alpha channel is ignored.

Definition at line 43 of file image.py.

def image.saturate (   grid  ) 

Clamps all values in a grid between 0 and 1.

Definition at line 203 of file image.py.

def image.threshold (   grid,
  value 
)

Definition at line 211 of file image.py.

def image.tile (   grid,
  m,
  n 
)

Returns a new grid, containing m by n copies of the given grid.

Definition at line 303 of file image.py.

def image.transpose (   grid  ) 

Definition at line 95 of file image.py.

def image.white_noise (   dims,
  period = 1 
)

Returns a grid containing white noise in the range [0 1].

Parameters:
dims The dimensions of the grid to return (as a xy-tuple).
period This is the period of different noise samples. For example, if the period is 2, then 2-by-2 windows in the grid will have the same value.

Definition at line 269 of file image.py.


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