> OK, be prepared to be surprised. Pull down the Image menu, go to Mode and
> gaze at the two entries "8 Bits / Channel" and "16 Bits / Channel."
> I've been using it for years; it ain't new.
> Yes, the Wikipedia article seems to verify what I was saying; that the same
> file can be referred to a 8-bit or 24-bit and both terms can be correct,
> depending on how you apportion the bits.
I think the key here is one has to indicate, for clarity sake, that the
reference is to "per channel"--but then, to be precise, one should indicate
how many channels are involved and what color mode.
There is a reference in the Photoshop help file:
In most cases, Lab, RGB, grayscale, and CMYK images contain 8 bits of data
per color channel. This translates to a 24?bit Lab bit depth (8 bits x 3
channels), a 24?bit RGB bit depth (8 bits x 3 channels), an 8?bit grayscale
bit depth (8 bits x 1 channel), and a 32?bit CMYK bit depth (8 bits x 4
channels). Photoshop can also work with Lab, RGB, CMYK, multichannel, and
grayscale images that contain 16 bits of data per color channel.
Additionally, Photoshop can work with RGB and grayscale images that contain
32 bits of data per color channel.
> http://www.luminous-landscape.com/tutorials/bit-depth.shtml, among
> other industry sources ...
I think the reference to RGB and printing is just some poor
editing/writing--I don't think the writer was actually saying printers print
in RGB. Since the website is photography-based (rather than commercial
printing), inkjet printers are often thought of as RGB printers because they
like to get their data in RGB and then convert to CMYK (or CcMmYKk, CMYKOG,
As an aside, one only needs about 200 shades of gray to get a decent photo
from commercial printing. It is the line screen (LPI), the resolution of the
output device (DPI), and the resolution of the image (PPI) that are
critical. Again, I think the website was dealing with photograph printing.
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