RGB to HSV via PIL and colorsys

问题

I have written a function which converts an Image from RGB > HSV. However, when I save the new image the only thing I get is a black image. What should I fix to get it solved?

Any help is kindly appreciated!

My code:

def HSVColor(img):
    if isinstance(img,Image):
        r,g,b = img.split()
        Hdat = []
        Sdat = []
        Vdat = [] 
        for rd,gn,bl in zip(r.getdata(),g.getdata(),b.getdata()) :
            h,s,v = colorsys.rgb_to_hsv(rd/255.,gn/255.,bl/255.)
            Hdat.append(int(h*255.))
            Sdat.append(int(l*255.))
            Vdat.append(int(s*255.))
        r.putdata(Hdat)
        g.putdata(Sdat)
        b.putdata(Vdat)
        return Image.merge('RGB',(r,g,b))
    else:
        return None

回答1:

Didn't you mix the module Image and its class Image?

The following code works for me (change the isinstance(img,Image.Image) part):

import Image, colorsys    

def HSVColor(img):
    if isinstance(img,Image.Image):
        r,g,b = img.split()
        Hdat = []
        Sdat = []
        Vdat = [] 
        for rd,gn,bl in zip(r.getdata(),g.getdata(),b.getdata()) :
            h,s,v = colorsys.rgb_to_hsv(rd/255.,gn/255.,bl/255.)
            Hdat.append(int(h*255.))
            Sdat.append(int(s*255.))
            Vdat.append(int(v*255.))
        r.putdata(Hdat)
        g.putdata(Sdat)
        b.putdata(Vdat)
        return Image.merge('RGB',(r,g,b))
    else:
        return None

a = Image.open('/tmp/a.jpg')
b = HSVColor(a)
b.save('/tmp/b.jpg')

回答2:

Just FYI, with a recent copy of Pillow, one should probably use

def rgb2hsv(image):
    return image.convert('HSV')

回答3:

i think you are trying to do the impossible, although you can transform rgb to hsv colour (and vice versa) values, according to wikipedia jpg images can only be stored in rgb or cmyk models.

来源：https://stackoverflow.com/questions/22236956/rgb-to-hsv-via-pil-and-colorsys