[iacolormap] [Up] [iargb2hsv] Color Processing

iatcrgb2ind
True color RGB to index image and colormap.

Synopsis

fi,cm = iatcrgb2ind( f )

Implemented in Python.

Input

f	Image. Gray-scale (uint8 or uint16) or binary image (logical). True color RGB image.

Output

fi,cm

Image. Gray-scale (uint8 or uint16) or binary image (logical).

Index image and its colormap.

Description

Converts a true color RGB image to the format of index image and a colormap.

Examples

>>> import Numeric

>>> r = [[4,5,6],[4,2,4]]

>>> g = [[0,1,2],[0,4,0]]

>>> b = [[1,0,2],[1,2,2]]

>>> f = Numeric.zeros((3,2,3))

>>> f[0,:,:], f[1,:,:], f[2,:,:] = r, g, b

>>> print f

[[[4 5 6]
  [4 2 4]]
 [[0 1 2]
  [0 4 0]]
 [[1 0 2]
  [1 2 2]]]

>>> (fi, tm) = iatcrgb2ind(f)

>>> print fi

[[1 0 3]
 [1 4 2]]

>>> print tm

[[5 1 0]
 [4 0 1]
 [4 0 2]
 [6 2 2]
 [2 4 2]]

Source Code
        def iatcrgb2ind(f):
    from Numeric import asarray, reshape, concatenate
    f = asarray(f)
    r, g, b = f[0,:,:], f[1,:,:], f[2,:,:]
    c = r + 256*g + 256*256*b
    (t,i,fi) = iaunique(c)
    siz = len(t)
    rt = reshape(map(lambda k:int(k%256), t), (siz,1))
    gt = reshape(map(lambda k:int((k%(256*256))/256.), t), (siz,1))
    bt = reshape(map(lambda k:int(k), t/(256*256.)), (siz,1))
    cm = concatenate((rt, gt, bt), axis=1)
    fi = reshape(fi, (f.shape[1], f.shape[2]))
    return fi,cm
    
      

[`iacolormap`] [Up] [`iargb2hsv`]