[Image-SIG] Answer - Help colors

[Oliver Albrecht]

Hello,

I not understand why nobody has answer me.
because you know that i can answer me self!?

>Oliver Albrecht wrote:
> 
> - How discover the nearest color?
> I want make a script to switch the colorpalette from images.
> 
> If it give another, better way tell it me. else i will post the
> completed script.

That is the request/answer:

if im_p.mode == "P":
     lut = im_p.resize((16, 16))
     lut.putdata(range(256))
     lut = lut.convert("RGB")
     palette1 = c_map.getdata()
     palette2 = lut.getdata()
     palette1 = list(palette1)
     palette2 = list(palette2)
     palette=set(palette1)
	## not common colors from palette2
     palette.difference_update(palette2)
     ocolors=set(palette2)
	## not common colors from palette1
     ocolors.difference_update(palette1)
	## give the colors a index
     palette = [(palette1.index(color), color) for color in palette]

     for (cr,cg,cb) in ocolors:
         opal_dict = {}
         for item in palette:
             r,g,b=item[1]
             opal_dict[abs(r-cr)+abs(g-cg)+abs(b-cb)]=item[0]
	## the nearest color
         palette2[palette2.index((cr,cg,cb))]= 
palette1[opal_dict[min(opal_dict.keys())]]

     for colorID in xrange(len(palette2)):
         palette2[colorID]=palette1.index(palette2[colorID])

     im_p.putpalette(c_map_pl)
     im_p=im_p.point(palette2)	##PIL(book)Returns a copy of the image
	#where each pixel has been mapped
	#through the given table.

> I want make a Mask from RGB Image from only one color . 
> Thats my try(has putdata() lesser performance?): 
[..snipped..]
> Is that efficient enough?

i mean this is better:

def MakeMask(im):
     data_list=[]
     bground=im.getpixel((0,0))
     for r, g, b in im.getdata():
         if (r,g,b) != bground: i=0
         else: i=255
         data_list.append(i)
     im = Image.new('1',im.size)
     im.putdata(data_list)
     return im

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