Permalink
Switch branches/tags
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
841 lines (683 sloc) 27.8 KB
# -*- coding: utf-8 -*-
# Copyright (c) 2010, Almar Klein, Ant1, Marius van Voorden
#
# This code is subject to the (new) BSD license:
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# * Neither the name of the <organization> nor the
# names of its contributors may be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
""" Module images2gif
Provides functionality for reading and writing animated GIF images.
Use writeGif to write a series of numpy arrays or PIL images as an
animated GIF. Use readGif to read an animated gif as a series of numpy
arrays.
Acknowledgements
----------------
Many thanks to Ant1 for:
* noting the use of "palette=PIL.Image.ADAPTIVE", which significantly
improves the results.
* the modifications to save each image with its own palette, or optionally
the global palette (if its the same).
Many thanks to Marius van Voorden for porting the NeuQuant quantization
algorithm of Anthony Dekker to Python (See the NeuQuant class for its
license).
This code is based on gifmaker (in the scripts folder of the source
distribution of PIL)
Some implementation details are ased on gif file structure as provided
by wikipedia.
"""
import os
try:
import PIL
from PIL import Image, ImageChops
from PIL.GifImagePlugin import getheader, getdata
except ImportError:
PIL = None
try:
import numpy as np
except ImportError:
np = None
try:
from scipy.spatial import cKDTree
except ImportError:
cKDTree = None
# getheader gives a 87a header and a color palette (two elements in a list).
# getdata()[0] gives the Image Descriptor up to (including) "LZW min code size".
# getdatas()[1:] is the image data itself in chuncks of 256 bytes (well
# technically the first byte says how many bytes follow, after which that
# amount (max 255) follows).
def checkImages(images):
""" checkImages(images)
Check numpy images and correct intensity range etc.
The same for all movie formats.
"""
# Init results
images2 = []
for im in images:
if PIL and isinstance(im, PIL.Image.Image):
# We assume PIL images are allright
images2.append(im)
elif np and isinstance(im, np.ndarray):
# Check and convert dtype
if im.dtype == np.uint8:
images2.append(im) # Ok
elif im.dtype in [np.float32, np.float64]:
im = im.copy()
im[im<0] = 0
im[im>1] = 1
im *= 255
images2.append( im.astype(np.uint8) )
else:
im = im.astype(np.uint8)
images2.append(im)
# Check size
if im.ndim == 2:
pass # ok
elif im.ndim == 3:
if im.shape[2] not in [3,4]:
raise ValueError('This array can not represent an image.')
else:
raise ValueError('This array can not represent an image.')
else:
raise ValueError('Invalid image type: ' + str(type(im)))
# Done
return images2
def intToBin(i):
""" Integer to two bytes """
# devide in two parts (bytes)
i1 = i % 256
i2 = int( i/256)
# make string (little endian)
return chr(i1) + chr(i2)
def getheaderAnim(im):
""" Animation header. To replace the getheader()[0] """
bb = "GIF89a"
bb += intToBin(im.size[0])
bb += intToBin(im.size[1])
bb += "\x87\x00\x00"
return bb
def getImageDescriptor(im):
""" Used for the local color table properties per image.
Otherwise global color table applies to all frames irrespective of
wether additional colours comes in play that require a redefined palette
Still a maximum of 256 color per frame, obviously.
Written by Ant1 on 2010-08-22
"""
bb = '\x2C' # Image separator,
bb += intToBin( 0 ) # Left position
bb += intToBin( 0 ) # Top position
bb += intToBin( im.size[0] ) # image width
bb += intToBin( im.size[1] ) # image height
bb += '\x87' # packed field : local color table flag1, interlace0, sorted table0, reserved00, lct size111=7=2^(7+1)=256.
# LZW minimum size code now comes later, begining of [image data] blocks
return bb
#def getAppExt(loops=float('inf')):
#compile error commented by zcwang
def getAppExt(loops=float(0)):
""" Application extention. Part that specifies amount of loops.
If loops is inf, it goes on infinitely.
"""
if loops == 0:
loops = 2**16-1
#bb = "" # application extension should not be used
# (the extension interprets zero loops
# to mean an infinite number of loops)
# Mmm, does not seem to work
if True:
bb = "\x21\xFF\x0B" # application extension
bb += "NETSCAPE2.0"
bb += "\x03\x01"
# if loops == float('inf'):
if loops == float(0):
loops = 2**16-1
bb += intToBin(loops)
bb += '\x00' # end
return bb
def getGraphicsControlExt(duration=0.1):
""" Graphics Control Extension. A sort of header at the start of
each image. Specifies transparancy and duration. """
bb = '\x21\xF9\x04'
bb += '\x08' # no transparancy
bb += intToBin( int(duration*100) ) # in 100th of seconds
bb += '\x00' # no transparant color
bb += '\x00' # end
return bb
def _writeGifToFile(fp, images, durations, loops):
""" Given a set of images writes the bytes to the specified stream.
"""
# Obtain palette for all images and count each occurance
palettes, occur = [], []
for im in images:
palettes.append(im.palette.getdata()[1])
for palette in palettes:
occur.append( palettes.count( palette ) )
# Select most-used palette as the global one (or first in case no max)
globalPalette = palettes[ occur.index(max(occur)) ]
# Init
frames = 0
firstFrame = True
for im, palette in zip(images, palettes):
if firstFrame:
# Write header
# Gather info
header = getheaderAnim(im)
appext = getAppExt(loops)
# Write
fp.write(header)
fp.write(globalPalette)
fp.write(appext)
# Next frame is not the first
firstFrame = False
if True:
# Write palette and image data
# Gather info
data = getdata(im)
imdes, data = data[0], data[1:]
graphext = getGraphicsControlExt(durations[frames])
# Make image descriptor suitable for using 256 local color palette
lid = getImageDescriptor(im)
# Write local header
if palette != globalPalette:
# Use local color palette
fp.write(graphext)
fp.write(lid) # write suitable image descriptor
fp.write(palette) # write local color table
fp.write('\x08') # LZW minimum size code
else:
# Use global color palette
fp.write(graphext)
fp.write(imdes) # write suitable image descriptor
# Write image data
for d in data:
fp.write(d)
# Prepare for next round
frames = frames + 1
fp.write(";") # end gif
return frames
## Exposed functions
def writeGif(filename, images, duration=0.1, repeat=True, dither=False, nq=0):
""" writeGif(filename, images, duration=0.1, repeat=True, dither=False)
Write an animated gif from the specified images.
Parameters
----------
filename : string
The name of the file to write the image to.
images : list
Should be a list consisting of PIL images or numpy arrays.
The latter should be between 0 and 255 for integer types, and
between 0 and 1 for float types.
duration : scalar or list of scalars
The duration for all frames, or (if a list) for each frame.
repeat : bool or integer
The amount of loops. If True, loops infinitetely.
dither : bool
Whether to apply dithering
nq : integer
If nonzero, applies the NeuQuant quantization algorithm to create
the color palette. This algorithm is superior, but slower than
the standard PIL algorithm. The value of nq is the quality
parameter. 1 represents the best quality. 10 is in general a
good tradeoff between quality and speed.
"""
# Check PIL
if PIL is None:
raise RuntimeError("Need PIL to write animated gif files.")
# Check images
images = checkImages(images)
# Check loops
if repeat is False:
loops = 1
elif repeat is True:
loops = 0 # zero means infinite
else:
loops = int(repeat)
# Convert to PIL images
images2 = []
for im in images:
if isinstance(im, Image.Image):
images2.append(im)
elif np and isinstance(im, np.ndarray):
if im.ndim==3 and im.shape[2]==3:
im = Image.fromarray(im,'RGB')
elif im.ndim==2:
im = Image.fromarray(im,'L')
images2.append(im)
# Convert to paletted PIL images
images, images2 = images2, []
if nq >= 1:
# NeuQuant algorithm
for im in images:
im = im.convert("RGBA") # NQ assumes RGBA
nq = NeuQuant(im, int(nq)) # Learn colors from image
if dither:
im = im.convert("RGB").quantize(palette=nq.paletteImage())
else:
im = nq.quantize(im) # Use to quantize the image itself
images2.append(im)
else:
# Adaptive PIL algorithm
AD = Image.ADAPTIVE
for im in images:
im = im.convert('P', palette=AD, dither=dither)
images2.append(im)
# Check duration
if hasattr(duration, '__len__'):
if len(duration) == len(images2):
durations = [d for d in duration]
else:
raise ValueError("len(duration) doesn't match amount of images.")
else:
duration = [duration for im in images2]
# Open file
fp = open(filename, 'wb')
# Write
try:
n = _writeGifToFile(fp, images2, duration, loops)
finally:
fp.close()
def readGif(filename, asNumpy=True):
""" readGif(filename, asNumpy=True)
Read images from an animated GIF file. Returns a list of numpy
arrays, or, if asNumpy is false, a list if PIL images.
"""
# Check PIL
if PIL is None:
raise RuntimeError("Need PIL to read animated gif files.")
# Check Numpy
if np is None:
raise RuntimeError("Need Numpy to read animated gif files.")
# Check whether it exists
if not os.path.isfile(filename):
raise IOError('File not found: '+str(filename))
# Load file using PIL
pilIm = PIL.Image.open(filename)
pilIm.seek(0)
# Read all images inside
images = []
try:
while True:
# Get image as numpy array
tmp = pilIm.convert() # Make without palette
a = np.asarray(tmp)
if len(a.shape)==0:
raise MemoryError("Too little memory to convert PIL image to array")
# Store, and next
images.append(a)
pilIm.seek(pilIm.tell()+1)
except EOFError:
pass
# Convert to normal PIL images if needed
if not asNumpy:
images2 = images
images = []
for im in images2:
images.append( PIL.Image.fromarray(im) )
# Done
return images
class NeuQuant:
""" NeuQuant(image, samplefac=10, colors=256)
samplefac should be an integer number of 1 or higher, 1
being the highest quality, but the slowest performance.
With avalue of 10, one tenth of all pixels are used during
training. This value seems a nice tradeof between speed
and quality.
colors is the amount of colors to reduce the image to. This
should best be a power of two.
See also:
http://members.ozemail.com.au/~dekker/NEUQUANT.HTML
License of the NeuQuant Neural-Net Quantization Algorithm
---------------------------------------------------------
Copyright (c) 1994 Anthony Dekker
Ported to python by Marius van Voorden in 2010
NEUQUANT Neural-Net quantization algorithm by Anthony Dekker, 1994.
See "Kohonen neural networks for optimal colour quantization"
in "network: Computation in Neural Systems" Vol. 5 (1994) pp 351-367.
for a discussion of the algorithm.
See also http://members.ozemail.com.au/~dekker/NEUQUANT.HTML
Any party obtaining a copy of these files from the author, directly or
indirectly, is granted, free of charge, a full and unrestricted irrevocable,
world-wide, paid up, royalty-free, nonexclusive right and license to deal
in this software and documentation files (the "Software"), including without
limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons who receive
copies from any such party to do so, with the only requirement being
that this copyright notice remain intact.
"""
NCYCLES = None # Number of learning cycles
NETSIZE = None # Number of colours used
SPECIALS = None # Number of reserved colours used
BGCOLOR = None # Reserved background colour
CUTNETSIZE = None
MAXNETPOS = None
INITRAD = None # For 256 colours, radius starts at 32
RADIUSBIASSHIFT = None
RADIUSBIAS = None
INITBIASRADIUS = None
RADIUSDEC = None # Factor of 1/30 each cycle
ALPHABIASSHIFT = None
INITALPHA = None # biased by 10 bits
GAMMA = None
BETA = None
BETAGAMMA = None
network = None # The network itself
colormap = None # The network itself
netindex = None # For network lookup - really 256
bias = None # Bias and freq arrays for learning
freq = None
pimage = None
# Four primes near 500 - assume no image has a length so large
# that it is divisible by all four primes
PRIME1 = 499
PRIME2 = 491
PRIME3 = 487
PRIME4 = 503
MAXPRIME = PRIME4
pixels = None
samplefac = None
a_s = None
def setconstants(self, samplefac, colors):
self.NCYCLES = 100 # Number of learning cycles
self.NETSIZE = colors # Number of colours used
self.SPECIALS = 3 # Number of reserved colours used
self.BGCOLOR = self.SPECIALS-1 # Reserved background colour
self.CUTNETSIZE = self.NETSIZE - self.SPECIALS
self.MAXNETPOS = self.NETSIZE - 1
self.INITRAD = self.NETSIZE/8 # For 256 colours, radius starts at 32
self.RADIUSBIASSHIFT = 6
self.RADIUSBIAS = 1 << self.RADIUSBIASSHIFT
self.INITBIASRADIUS = self.INITRAD * self.RADIUSBIAS
self.RADIUSDEC = 30 # Factor of 1/30 each cycle
self.ALPHABIASSHIFT = 10 # Alpha starts at 1
self.INITALPHA = 1 << self.ALPHABIASSHIFT # biased by 10 bits
self.GAMMA = 1024.0
self.BETA = 1.0/1024.0
self.BETAGAMMA = self.BETA * self.GAMMA
self.network = np.empty((self.NETSIZE, 3), dtype='float64') # The network itself
self.colormap = np.empty((self.NETSIZE, 4), dtype='int32') # The network itself
self.netindex = np.empty(256, dtype='int32') # For network lookup - really 256
self.bias = np.empty(self.NETSIZE, dtype='float64') # Bias and freq arrays for learning
self.freq = np.empty(self.NETSIZE, dtype='float64')
self.pixels = None
self.samplefac = samplefac
self.a_s = {}
def __init__(self, image, samplefac=10, colors=256):
# Check Numpy
if np is None:
raise RuntimeError("Need Numpy for the NeuQuant algorithm.")
# Check image
if image.size[0] * image.size[1] < NeuQuant.MAXPRIME:
raise IOError("Image is too small")
assert image.mode == "RGBA"
# Initialize
self.setconstants(samplefac, colors)
self.pixels = np.fromstring(image.tostring(), np.uint32)
self.setUpArrays()
self.learn()
self.fix()
self.inxbuild()
def writeColourMap(self, rgb, outstream):
for i in range(self.NETSIZE):
bb = self.colormap[i,0];
gg = self.colormap[i,1];
rr = self.colormap[i,2];
out.write(rr if rgb else bb)
out.write(gg)
out.write(bb if rgb else rr)
return self.NETSIZE
def setUpArrays(self):
self.network[0,0] = 0.0 # Black
self.network[0,1] = 0.0
self.network[0,2] = 0.0
self.network[1,0] = 255.0 # White
self.network[1,1] = 255.0
self.network[1,2] = 255.0
# RESERVED self.BGCOLOR # Background
for i in range(self.SPECIALS):
self.freq[i] = 1.0 / self.NETSIZE
self.bias[i] = 0.0
for i in range(self.SPECIALS, self.NETSIZE):
p = self.network[i]
p[:] = (255.0 * (i-self.SPECIALS)) / self.CUTNETSIZE
self.freq[i] = 1.0 / self.NETSIZE
self.bias[i] = 0.0
# Omitted: setPixels
def altersingle(self, alpha, i, b, g, r):
"""Move neuron i towards biased (b,g,r) by factor alpha"""
n = self.network[i] # Alter hit neuron
n[0] -= (alpha*(n[0] - b))
n[1] -= (alpha*(n[1] - g))
n[2] -= (alpha*(n[2] - r))
def geta(self, alpha, rad):
try:
return self.a_s[(alpha, rad)]
except KeyError:
length = rad*2-1
mid = length/2
q = np.array(range(mid-1,-1,-1)+range(-1,mid))
a = alpha*(rad*rad - q*q)/(rad*rad)
a[mid] = 0
self.a_s[(alpha, rad)] = a
return a
def alterneigh(self, alpha, rad, i, b, g, r):
if i-rad >= self.SPECIALS-1:
lo = i-rad
start = 0
else:
lo = self.SPECIALS-1
start = (self.SPECIALS-1 - (i-rad))
if i+rad <= self.NETSIZE:
hi = i+rad
end = rad*2-1
else:
hi = self.NETSIZE
end = (self.NETSIZE - (i+rad))
a = self.geta(alpha, rad)[start:end]
p = self.network[lo+1:hi]
p -= np.transpose(np.transpose(p - np.array([b, g, r])) * a)
#def contest(self, b, g, r):
# """ Search for biased BGR values
# Finds closest neuron (min dist) and updates self.freq
# finds best neuron (min dist-self.bias) and returns position
# for frequently chosen neurons, self.freq[i] is high and self.bias[i] is negative
# self.bias[i] = self.GAMMA*((1/self.NETSIZE)-self.freq[i])"""
#
# i, j = self.SPECIALS, self.NETSIZE
# dists = abs(self.network[i:j] - np.array([b,g,r])).sum(1)
# bestpos = i + np.argmin(dists)
# biasdists = dists - self.bias[i:j]
# bestbiaspos = i + np.argmin(biasdists)
# self.freq[i:j] -= self.BETA * self.freq[i:j]
# self.bias[i:j] += self.BETAGAMMA * self.freq[i:j]
# self.freq[bestpos] += self.BETA
# self.bias[bestpos] -= self.BETAGAMMA
# return bestbiaspos
def contest(self, b, g, r):
""" Search for biased BGR values
Finds closest neuron (min dist) and updates self.freq
finds best neuron (min dist-self.bias) and returns position
for frequently chosen neurons, self.freq[i] is high and self.bias[i] is negative
self.bias[i] = self.GAMMA*((1/self.NETSIZE)-self.freq[i])"""
i, j = self.SPECIALS, self.NETSIZE
dists = abs(self.network[i:j] - np.array([b,g,r])).sum(1)
bestpos = i + np.argmin(dists)
biasdists = dists - self.bias[i:j]
bestbiaspos = i + np.argmin(biasdists)
self.freq[i:j] *= (1-self.BETA)
self.bias[i:j] += self.BETAGAMMA * self.freq[i:j]
self.freq[bestpos] += self.BETA
self.bias[bestpos] -= self.BETAGAMMA
return bestbiaspos
def specialFind(self, b, g, r):
for i in range(self.SPECIALS):
n = self.network[i]
if n[0] == b and n[1] == g and n[2] == r:
return i
return -1
def learn(self):
biasRadius = self.INITBIASRADIUS
alphadec = 30 + ((self.samplefac-1)/3)
lengthcount = self.pixels.size
samplepixels = lengthcount / self.samplefac
delta = samplepixels / self.NCYCLES
alpha = self.INITALPHA
i = 0;
rad = biasRadius >> self.RADIUSBIASSHIFT
if rad <= 1:
rad = 0
print "Beginning 1D learning: samplepixels =",samplepixels," rad =", rad
step = 0
pos = 0
if lengthcount%NeuQuant.PRIME1 != 0:
step = NeuQuant.PRIME1
elif lengthcount%NeuQuant.PRIME2 != 0:
step = NeuQuant.PRIME2
elif lengthcount%NeuQuant.PRIME3 != 0:
step = NeuQuant.PRIME3
else:
step = NeuQuant.PRIME4
i = 0
printed_string = ''
while i < samplepixels:
if i%100 == 99:
tmp = '\b'*len(printed_string)
printed_string = str((i+1)*100/samplepixels)+"%\n"
print tmp + printed_string,
p = self.pixels[pos]
r = (p >> 16) & 0xff
g = (p >> 8) & 0xff
b = (p ) & 0xff
if i == 0: # Remember background colour
self.network[self.BGCOLOR] = [b, g, r]
j = self.specialFind(b, g, r)
if j < 0:
j = self.contest(b, g, r)
if j >= self.SPECIALS: # Don't learn for specials
a = (1.0 * alpha) / self.INITALPHA
self.altersingle(a, j, b, g, r)
if rad > 0:
self.alterneigh(a, rad, j, b, g, r)
pos = (pos+step)%lengthcount
i += 1
if i%delta == 0:
alpha -= alpha / alphadec
biasRadius -= biasRadius / self.RADIUSDEC
rad = biasRadius >> self.RADIUSBIASSHIFT
if rad <= 1:
rad = 0
print "Finished 1D learning: final alpha =",(1.0*alpha)/self.INITALPHA,"!"
def fix(self):
for i in range(self.NETSIZE):
for j in range(3):
x = int(0.5 + self.network[i,j])
x = max(0, x)
x = min(255, x)
self.colormap[i,j] = x
self.colormap[i,3] = i
def inxbuild(self):
previouscol = 0
startpos = 0
for i in range(self.NETSIZE):
p = self.colormap[i]
q = None
smallpos = i
smallval = p[1] # Index on g
# Find smallest in i..self.NETSIZE-1
for j in range(i+1, self.NETSIZE):
q = self.colormap[j]
if q[1] < smallval: # Index on g
smallpos = j
smallval = q[1] # Index on g
q = self.colormap[smallpos]
# Swap p (i) and q (smallpos) entries
if i != smallpos:
p[:],q[:] = q, p.copy()
# smallval entry is now in position i
if smallval != previouscol:
self.netindex[previouscol] = (startpos+i) >> 1
for j in range(previouscol+1, smallval):
self.netindex[j] = i
previouscol = smallval
startpos = i
self.netindex[previouscol] = (startpos+self.MAXNETPOS) >> 1
for j in range(previouscol+1, 256): # Really 256
self.netindex[j] = self.MAXNETPOS
def paletteImage(self):
""" PIL weird interface for making a paletted image: create an image which
already has the palette, and use that in Image.quantize. This function
returns this palette image. """
if self.pimage is None:
palette = []
for i in range(self.NETSIZE):
palette.extend(self.colormap[i][:3])
palette.extend([0]*(256-self.NETSIZE)*3)
# a palette image to use for quant
self.pimage = Image.new("P", (1, 1), 0)
self.pimage.putpalette(palette)
return self.pimage
def quantize(self, image):
""" Use a kdtree to quickly find the closest palette colors for the pixels """
if cKDTree:
return self.quantize_with_scipy(image)
else:
print 'Scipy not available, falling back to slower version.'
return self.quantize_without_scipy(image)
def quantize_with_scipy(self, image):
w,h = image.size
px = np.asarray(image).copy()
px2 = px[:,:,:3].reshape((w*h,3))
kdtree = cKDTree(self.colormap[:,:3],leafsize=10)
result = kdtree.query(px2)
colorindex = result[1]
print "Distance:", (result[0].sum()/(w*h))
px2[:] = self.colormap[colorindex,:3]
return Image.fromarray(px).convert("RGB").quantize(palette=self.paletteImage())
def quantize_without_scipy(self, image):
"""" This function can be used if no scipy is availabe.
It's 7 times slower though.
"""
w,h = image.size
px = np.asarray(image).copy()
memo = {}
for j in range(w):
for i in range(h):
key = (px[i,j,0],px[i,j,1],px[i,j,2])
try:
val = memo[key]
except KeyError:
val = self.convert(key)
memo[key] = val
px[i,j,0],px[i,j,1],px[i,j,2] = val
return Image.fromarray(px).convert("RGB").quantize(palette=self.paletteImage())
def convert(self, (r, g, b)):
i = self.inxsearch(r, g, b)
return self.colormap[i,:3]
def inxsearch(self, r, g, b):
"""Search for BGR values 0..255 and return colour index"""
dists = (self.colormap[:,:3] - np.array([r,g,b]))
a= np.argmin((dists*dists).sum(1))
return a
if __name__ == '__main__':
im = np.zeros((200,200), dtype=np.uint8)
im[10:30,:] = 100
im[:,80:120] = 255
im[-50:-40,:] = 50
images = [im*1.0, im*0.8, im*0.6, im*0.4, im*0]
writeGif('lala3.gif',images, duration=0.5, dither=0)