Re: Question about Thon rings



On Jan 26, 2:13 am, "heini" <buerg...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
Hi Eduardo,

On Jan 25, 8:43 pm, "Eduardo" <esanz...@xxxxxxxxx> wrote:> I have a question about Thon rings. I have realized recently that when
I take pictures using the CCD camera I get better Thon rings than whenwhich color depth? 8bit grey?

16 bits grey scale

I take the image using film (less rings and more diffuse). The specimenthat's what your eye tells you

And some analytical tools to fit the contrast transfer function (CTF).

I guess, that your camera does not achieve approximately the same depth
of information as you film does.
That's what I think from your description.
Next, your monitor will never be able to show you all information
achieved by a good camera (32 bit grey).
Contrast settings in acquisition and display may show information, that
isn't there.

To make it short, if you are using 8 bitCCD, you will not be able to
achieve full information and this bit of information looks like better
contrast to your eyes. (because 256 grey levels are not much compared
to a film!)
Try scanning your films with 8/16/32 bit grey values, and then have a
look at the digital images...

I scan film in 16 bits with a very good scanner.

yours, Heinrich

I don't think that the number of bits of the image is not the problem
(both have the same number of bits, and the CCD FFT looks much better)
.. I think that there is something else. Any guest?
Thank you.

.

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