Re: 16 bits = 15 bits in Photoshop?
Re: 16 bits = 15 bits in Photoshop?
- Subject: Re: 16 bits = 15 bits in Photoshop?
- From: Ray Maxwell <email@hidden>
- Date: Tue, 19 Apr 2005 20:36:38 -0700
Hi Graeme,
I said exactly the same thing about 40 messages back on this thread.
I agree that this is the reason that we have a difference of opinion
expressed on
this subject. Very few people have seen real photographic images that
have a
low enough noise level to see the difference between 16 bit and 8 bit
images.
We will see if anyone listens to your reasoning. I for one and maybe
the only
one, agrees that this is at the root of this disagreement.
Thanks, now there are two of us that agree.
Ray Maxwell
Graeme Gill wrote:
A crucial factor in running such an experiment, is the level of
noise (or grain if you like), in the images. Such noise acts
as a "dither", that conceals quantization artefacts quite well.
A lot of real world photographs fall into this category, due
both to the nature of real world objects, and the practical
limitations of capturing photons.
The opposite extreme is a synthetic computer image generated
without any surface textures.
If you run your experiment with the first type of image,
I can well imagine coming to the conclusion that 8 bits
works remarkably well.
Using the second type of image, I can well imagine coming
to the conclusion that 8 bits is woefully inadequate.
A good example of a controlled series of such experiments is
reported on in "Precision Requirements for Digital Color Reproduction",
Mike Stokes, Mark D. Fairchild, Roy S. Berns, ACM Transactions on
Graphics,
Vol. 11, No. 4, October 1992, pp 406. Using real world images, they
came to the conclusion that 10-11 bits of precision are needed, when
represented in CIELAB colorspace.
Graeme Gill.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden