[magick-users] Identify-ing a JPEG image

[Wolfgang Hugemann]

When identifying a JPEG image via

-identify - verbose something.jpg

I get (amongst others) the lines:

JPEG-Colorspace: 2
JPEG-Sampling-factors: 2x2,1x1,1x1

I bet that JPEG Colorspace no. 2 is RGB (?). But I am really confused by 
the sampling factors, which I attribute to Y, Cr, Cb. Now, Y should not 
be sub-sampled at all and Cr and Cb should be subsampled either by the 
factor 2 (when counting in just one direction) or 4 (when counting the 
amount of pixels).

So what does the above line this really tell us? I could not find any 
detailed explanation for the output of 'identify'.

BTW: Is there any way that I can visualize the Y, Cr, Cb channels of the 
JPEG, i.e. split the Image into these channels? As IM recognizes JPEG as 
RGB, the simple -separate option will not do.

Greetings from Münster, Germany
Wolfgang Hugemann