Discussion of 16 bit image editing vs 8 bit

RF
Posted By
Robert Feinman
Nov 4, 2003
Views
537
Replies
9
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Closed
Since the new version of photoshop adds improved 16 bit image processing I decided to see if there is much difference between editing 16 bit and 8 bit images. So I’ve added a tip highlighting the differences between using 8 and 16 bit depth files for capture and editing to my tips page.
I did the same edits on both versions of the image using photoshop 7.

I leave it to you to decide as to the results, I’m still pondering the meaning..

Follow the link to the tips section on my home page and then scroll down to the New! tips.

Robert D Feinman

Landscapes, Cityscapes, Panoramic Photographs: http://robertdfeinman.com

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MR
Mike Russell
Nov 5, 2003
Robert Feinman wrote:
Since the new version of photoshop adds improved 16 bit image processing I
decided to see if there is much difference between editing 16 bit and 8 bit images. So I’ve added a tip highlighting the differences between using 8 and 16 bit
depth files for capture and editing to my tips page.
I did the same edits on both versions of the image using photoshop 7.
I leave it to you to decide as to the results, I’m still pondering the meaning..

Follow the link to the tips section on my home page and then scroll down
to the New! tips.

Good page.

One thing to keep in mind is that PS adds 1/2 bit of noise when it converts from 16 bit to 8 bit. I’ve seen discussions of 8 vs 16 bit that ignore this and rely only on histograms to illustrate the "point" that 16 bit is superior – yours is a refreshing change from this because you actually compare the two images..

Much of the difference between the two images, including the histogram combing, may be due to that factor alone.



Mike Russell
http://www.curvemeister.com
http://www.zocalo.net/~mgr
http://geigy.2y.net
Nov 5, 2003
Robert Feinman wrote in
news::

http://robertdfeinman.com

Well……The 16 bit, at that enlargement is what I would call a "tad" sharper. Not a very technical term, I know. The question would be, would the difference be perceived in a normal print by the average viewer? Probably not. At an extreme enlargement, pixalization becomes the overiding factor, I think.
My ideal print is one that is "perceived" to be as sharp an image as one could get. Going back to my photo printing days, I remember the endless lens testing, shooting and printing resolution charts to achieve the sharpest possible image only to be defeated by the grain of the film. Then there was the diffuse light sources vs. condensors. To add to that, if you are old enough, there was the old debate over Panatomic X vs. Plus X, and Microdol develpor vs. D 76 and a myriad of other sharpness issues! The quest for sharpness never ends, but that’s what make this field interesting and challenging.
Robert

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F
Flycaster
Nov 5, 2003
"Mike Russell" wrote in message
Robert Feinman wrote:
Since the new version of photoshop adds improved 16 bit image processing I
decided to see if there is much difference between editing 16 bit and 8 bit images. So I’ve added a tip highlighting the differences between using 8 and 16 bit
depth files for capture and editing to my tips page.
I did the same edits on both versions of the image using photoshop 7.
I leave it to you to decide as to the results, I’m still pondering the meaning..

Follow the link to the tips section on my home page and then scroll down
to the New! tips.

Good page.

One thing to keep in mind is that PS adds 1/2 bit of noise when it
converts
from 16 bit to 8 bit. I’ve seen discussions of 8 vs 16 bit that ignore
this
and rely only on histograms to illustrate the "point" that 16 bit is superior – yours is a refreshing change from this because you actually compare the two images..

Much of the difference between the two images, including the histogram combing, may be due to that factor alone.

I’m unclear here. At what point did Photoshop "convert" this image? I thought the page indicated that they were two discrete scans.

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WS
Warren Sarle
Nov 5, 2003
"Robert Feinman" wrote in message
Since the new version of photoshop adds improved 16 bit image processing I decided to see if there is much difference between editing 16 bit and 8
bit images.
So I’ve added a tip highlighting the differences between using 8 and 16
bit
depth files for capture and editing to my tips page.
I did the same edits on both versions of the image using photoshop 7.
I leave it to you to decide as to the results, I’m still pondering the meaning..

Follow the link to the tips section on my home page and then scroll down to the New! tips.

Robert D Feinman

Landscapes, Cityscapes, Panoramic Photographs: http://robertdfeinman.com

A grainy, film-based image is not the place you are likely to see any difference between 8 and 16 bit editing. Posterization is more likely to show up in a digital photo of a very smooth subject with a shallow gradient that you want to change to a steep gradient, such as a light blue sky that is burned in for dramatic effect. Also, stacking up lots of adjustment layers and using Lab mode make posterization worse.

Although I routinely use 16-bit mode for any major adjustments, I doubt that anybody is likely to see any difference between 8 and 16 bit editing for ordinary photographs that are reasonably well exposed. But I do some weird things where it makes a big difference.
MR
Mike Russell
Nov 5, 2003
Flycaster wrote:

[re Photshop’s treatment of 16 bit vs 8 bit images, c.f. http://robertdfeinman.com ]

I’m unclear here. At what point did Photoshop "convert" this image? I thought the page indicated that they were two discrete scans.

There are two different scans in Robert’s example.

Photoshop converts from 16 to 8 bit when it displays the image, and when calculating the histogram.

In both cases, the 1/2 bit of noise involved in that 16->8 bit conversion can cause a change in appearance that would smooth out posterization and banding, and also smooth out the histogram. This is just one of the issues that make comparison of actual 16 vs 8 bit images problematical.



Mike Russell
http://www.curvemeister.com
http://www.zocalo.net/~mgr
http://geigy.2y.net
F
Flycaster
Nov 5, 2003
"Mike Russell" wrote in message
Flycaster wrote:

[re Photshop’s treatment of 16 bit vs 8 bit images, c.f. http://robertdfeinman.com ]

I’m unclear here. At what point did Photoshop "convert" this image? I thought the page indicated that they were two discrete scans.

There are two different scans in Robert’s example.

Photoshop converts from 16 to 8 bit when it displays the image, and when calculating the histogram.

In both cases, the 1/2 bit of noise involved in that 16->8 bit conversion can cause a change in appearance that would smooth out posterization and banding, and also smooth out the histogram. This is just one of the
issues
that make comparison of actual 16 vs 8 bit images problematical.

Huh, I did not know this about the histogram; I’d always thought it was based on the actual underlying pixel data unless it was cached. It’s odd that Fraser/Blatner have never mentioned this quirk before, and it would indeed make a true comparison problematic, or at the least somewhat inaccurate.

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H
Hecate
Nov 6, 2003
On 4 Nov 2003 19:17:59 -0600, Anonymous <Nobody> wrote:

Robert Feinman wrote in
news::

http://robertdfeinman.com

Well……The 16 bit, at that enlargement is what I would call a "tad" sharper. Not a very technical term, I know. The question would be, would the difference be perceived in a normal print by the average viewer? Probably not. At an extreme enlargement, pixalization becomes the overiding factor, I think.
My ideal print is one that is "perceived" to be as sharp an image as one could get. Going back to my photo printing days, I remember the endless lens testing, shooting and printing resolution charts to achieve the sharpest possible image only to be defeated by the grain of the film. Then there was the diffuse light sources vs. condensors. To add to that, if you are old enough, there was the old debate over Panatomic X vs. Plus X, and Microdol develpor vs. D 76 and a myriad of other sharpness issues! The quest for sharpness never ends, but that’s what make this field interesting and challenging.
Robert

And sharpness is not the whole issue either. I still use, and will gone on doing so until they either stop making it or death overtakes me (whichever comes first <g>) Kodak’s Tri-X as my standard B&W film. Why? Because I love the grain – i positively *want* to see the grain 😉



Hecate

veni, vidi, relinqui
Nov 6, 2003
Hecate wrote in
news::

On 4 Nov 2003 19:17:59 -0600, Anonymous <Nobody> wrote:
Robert Feinman wrote in
news::

http://robertdfeinman.com

Well……The 16 bit, at that enlargement is what I would call a "tad" sharper. Not a very technical term, I know. The question would be, would the difference be perceived in a normal print by the average viewer? Probably not. At an extreme enlargement, pixalization becomes the overiding factor, I think.
My ideal print is one that is "perceived" to be as sharp an image as
one
could get. Going back to my photo printing days, I remember the
endless
lens testing, shooting and printing resolution charts to achieve the sharpest possible image only to be defeated by the grain of the film. Then there was the diffuse light sources vs. condensors. To add to that, if you are old enough, there was the old debate over Panatomic X vs. Plus X, and Microdol develpor vs. D 76 and a myriad of other sharpness issues! The quest for sharpness never ends, but that’s what make this field interesting and challenging.
Robert

And sharpness is not the whole issue either. I still use, and will gone on doing so until they either stop making it or death overtakes me (whichever comes first <g>) Kodak’s Tri-X as my standard B&W film. Why? Because I love the grain – i positively *want* to see the grain 😉



Hecate

veni, vidi, relinqui

To which I will add, that I agree. Were it not for my advanced age which limits the time I can stand in a darkroom, I would still be doing the same. I first and only preference was for Tri-X developed 1:1 in D76. Nothing better!
Robert

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H
Hecate
Nov 7, 2003
On 5 Nov 2003 20:08:16 -0600, Anonymous <Nobody> wrote:

And sharpness is not the whole issue either. I still use, and will gone on doing so until they either stop making it or death overtakes me (whichever comes first <g>) Kodak’s Tri-X as my standard B&W film. Why? Because I love the grain – i positively *want* to see the grain 😉



Hecate

veni, vidi, relinqui

To which I will add, that I agree. Were it not for my advanced age which limits the time I can stand in a darkroom, I would still be doing the same. I first and only preference was for Tri-X developed 1:1 in D76. Nothing better!
Robert
I’m glad there’s still a few of us left 🙂



Hecate

veni, vidi, relinqui

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