Digital cameras and grain in channels question

[mistercitizen]

I don't know a great deal about digital cameras, but was wondering about different ways to assess the quality of image from Digi cameras (apart from mega-pixel comparisons)

I think I read somewhere, that by going through each channel individually, one can more easily see any shortcomings of the camera in question, especially with regards to grain within an image.

Sure enough, I tried this on some digi images I've recieved, and the Blue channel in particular looked absolutely horrible, when compared to the composite view. This grain was nowhere as apparent when viewing in composite channel mode.

Is this a good way to assess the quality of digital images?

And is this something I should be looking at when I come to buying a digital camera for myself?

 

[kiddpete]

I've never heard anyone suggest that digital pictures have a 'grain'. The metaphore would seem to refer to the number of pixels in the camera's senser. The more pixels, the finer the 'grain'.

Megapixels should certainly be considered. Most good cameras these days are in the 6-8 megapixel range. However, the camera must process the pixel values to produce an image, so you've got to judge by the quality of the image produced. That means color, saturation, contrast, white balance, etc. Also, the lenses available including special features like image stabilization.

I certainly wouldn't try to judge based on a color channel. A picture might have very little blue in one part, and a lot in another. This probably wouldn't look too good by itself.

 

[mistercitizen]

Sorry, substitute the phrase "grain" for noise.

What if the image has relatively similar amounts of info in each channel?