Benefits of 16-bit editing?

S
Posted By
Sonrise
Aug 14, 2005
Views
442
Replies
4
Status
Closed
Hi all. I’m considering moving up from Elements 3 to CS2 in order to work in 16-bit format. My question for the experts is whether there is a significant difference in image quality comparing 8-bit to 16-bit. My understanding is that with 16-bit you have greater tonal range and you lose less information when editing. Thanks for all responses.

Sonrise

How to Master Sharpening in Photoshop

Give your photos a professional finish with sharpening in Photoshop. Learn to enhance details, create contrast, and prepare your images for print, web, and social media.

BH
Bill Hilton
Aug 14, 2005
Sonrise writes …

I’m considering moving up from Elements 3 to CS2 in order to work in 16-bit format.

Elements 3 has 16 bit support for the basic tools, but not with adjustment layers. You can make the key tonal moves with Levels and Hue/Sat in E 3. E 3’s 16 bit support is similar to Photoshop V6’s 16 bit support. So maybe this is not enough reason to upgrade?

My understanding is that with 16-bit you have greater tonal range

No, the tonal range is the same. You have finer granularity between the extremes of the tonal range, but the tonal range is the same.

… and you lose less information when editing.

This is true if you’re making major edits but not a big deal if you’re not. The theory is that if you have gaps of 3 or more in the histogram this will show up on the final print (per the Fraser link below). With the Ansel Adams link below it’s clear you’ll have significant gaps in the histogram, but this could have been avoided by doing a better initial scan, which typically works on high bit data, and setting the end points more aggressively at that stage.

My question for the experts is whether there is a significant difference in image quality comparing 8-bit to 16-bit.

This used to be a highly charged question, with many people lining up on the 16 bit side saying "of course there’s a significant difference" (hey, 16 is bigger than 8, right?) and a few people (but a vocal few) saying you can’t see the difference in actual outputs like prints (Dan Margulis is the best known guy in this camp). You can read a couple of the "pro 16-bit" arguments here …
http://www.creativepro.com/story/feature/7627.html
http://www.inkjetart.com/2450/48bit/page4.html
…. as you can see from these articles you’ll definitely get smoother gradients and better looking histograms if you use 16 bit (grin). Whether or not this translates into prints is less clear.

I used to believe it was self-evident that 16 bit was far superior (I’m a Bruce Fraser fan and he wrote the article in the first link) but after reading Margulis I tried to keep an open mind. One of Margulis’ fans (I think Mike Russell, but may be wrong) created a challenge a few years back offering a prize ($50? $100?) for anyone who could show that a file edited in 16 bits was visually superior at output to the same file edited with the same steps in 8 bits. As I remember, he lost the bet when someone came up with such a file, but probably 90-95% of the files submitted didn’t seem to be any different. (Maybe Mike can fill in with more accurate details, I didn’t participate in it myself).

So anyway, it comes down to a religious preference I guess … I have fast computers and large disks so I always work in 16 bit for anything I intend to print, but I’m sure that for the vast majority of my images it wouldn’t make any difference at all since I’m not making major tonal edits. For sure if you get it right in the camera and only have to make minor edits in Photoshop it won’t matter.

A compromise is to convert the RAW file or scan in 16 bit mode, make the initial tonal edits on the 16 bit file (ie Levels, Hue/Sat with E
3) and then convert to 8 bit mode for local edits or final touches.
This used to be a common workflow before Photoshop added adjustment layers for 16 bit files.

Bill
H
Harvey
Aug 14, 2005
thankx for the info. I think the last part is the best. Going from raw to 16 then to 8 would be best. Do you save them all seperate or is the 16 and 8 the same file.
"Bill Hilton" wrote in message
Sonrise writes …

I’m considering moving up from Elements 3 to CS2 in order to work in 16-bit format.

Elements 3 has 16 bit support for the basic tools, but not with adjustment layers. You can make the key tonal moves with Levels and Hue/Sat in E 3. E 3’s 16 bit support is similar to Photoshop V6’s 16 bit support. So maybe this is not enough reason to upgrade?
My understanding is that with 16-bit you have greater tonal range

No, the tonal range is the same. You have finer granularity between the extremes of the tonal range, but the tonal range is the same.
… and you lose less information when editing.

This is true if you’re making major edits but not a big deal if you’re not. The theory is that if you have gaps of 3 or more in the histogram this will show up on the final print (per the Fraser link below). With the Ansel Adams link below it’s clear you’ll have significant gaps in the histogram, but this could have been avoided by doing a better initial scan, which typically works on high bit data, and setting the end points more aggressively at that stage.

My question for the experts is whether there is a significant difference in image quality comparing 8-bit to 16-bit.

This used to be a highly charged question, with many people lining up on the 16 bit side saying "of course there’s a significant difference" (hey, 16 is bigger than 8, right?) and a few people (but a vocal few) saying you can’t see the difference in actual outputs like prints (Dan Margulis is the best known guy in this camp). You can read a couple of the "pro 16-bit" arguments here …
http://www.creativepro.com/story/feature/7627.html
http://www.inkjetart.com/2450/48bit/page4.html
… as you can see from these articles you’ll definitely get smoother gradients and better looking histograms if you use 16 bit (grin). Whether or not this translates into prints is less clear.
I used to believe it was self-evident that 16 bit was far superior (I’m a Bruce Fraser fan and he wrote the article in the first link) but after reading Margulis I tried to keep an open mind. One of Margulis’ fans (I think Mike Russell, but may be wrong) created a challenge a few years back offering a prize ($50? $100?) for anyone who could show that a file edited in 16 bits was visually superior at output to the same file edited with the same steps in 8 bits. As I remember, he lost the bet when someone came up with such a file, but probably 90-95% of the files submitted didn’t seem to be any different. (Maybe Mike can fill in with more accurate details, I didn’t participate in it myself).
So anyway, it comes down to a religious preference I guess … I have fast computers and large disks so I always work in 16 bit for anything I intend to print, but I’m sure that for the vast majority of my images it wouldn’t make any difference at all since I’m not making major tonal edits. For sure if you get it right in the camera and only have to make minor edits in Photoshop it won’t matter.

A compromise is to convert the RAW file or scan in 16 bit mode, make the initial tonal edits on the 16 bit file (ie Levels, Hue/Sat with E
3) and then convert to 8 bit mode for local edits or final touches.
This used to be a common workflow before Photoshop added adjustment layers for 16 bit files.

Bill
MR
Mike Russell
Aug 15, 2005
"Bill Hilton" wrote in message
One of Margulis’ fans (I think Mike Russell, but may be wrong) created a challenge a few
years back offering a prize ($50? $100?) for anyone who could show that a file edited in 16 bits was visually superior at output to the same file edited with the same steps in 8 bits.

As I remember, he lost the
bet when someone came up with such a file, but probably 90-95% of the files submitted didn’t seem to be any different. (Maybe Mike can fill in with more accurate details, I didn’t participate in it myself).

LOL – yes, that was me. There were a few problems with the 16 bit challenge, not the least of which was the tremendous number of emails and posts complaining about the concept of the challenge. Much more verbiage was spent on that, than on the contest itself..

The basic idea was for people to send me images corrected in 16 bits, and have them judged, side by side, with an image corrected by myself, starting with an 8 bit version of the 16 bit original. To make a long story short, I lost the contest because I overdid the detail in the shadows and the highlights in one of the images.

I send the $100 check to the winner – a photographer in Greenland – and considered it a cheap education in humility, which many have remarked I am in dire need of. In this, my own change of attitude mirrors Bill’s, who started on the other side with the assumption that 16 bit originals would be better.

As time passes, and the technology moves forward, I think the question of whether to capture in 16 bit is becoming moot. It is easy now to capture 12 bit raw images, and I have verified that they do contain much valid shadow detail that is not available in the 8 bit version of the same exposure. As ADC’s become cheaper, scanner manufacturers have moved their image processing into the digital realm, and this means that hibit scans have more detail than they did several years ago.

The final answer may change, but the criteria are the same. If you are a consumer of technology, first educate yourself, then believe in what you can see, yourself, in your own images. Anything else is just smoke and mirrors. This remains the best insurance against buying bridges from naked emperors. Personally, I still use 8 bit for nearly all of my images, but I recognize and respect the importance of hibit editing to many of my customers.

In a few years, perhaps, we will have a digital camera that captures floating point HDR images, and the question of whether to edit in that number system will present us all with a different set of choices, and challenges for toolmakers such as myself. These are exciting, and sometimes overheated times.

The technology changes, and those of us who are flexible will change our minds.

Mike Russell
www.curvemeister.com
S
Sean
Aug 15, 2005
On 14 Aug 2005 07:15:38 -0700, "Bill Hilton"
reverently intoned upon the aether:

My understanding is that with 16-bit you have greater tonal range

No, the tonal range is the same. You have finer granularity between the extremes of the tonal range, but the tonal range is the same.

From what I have read without running the tests to verify is that 16-bit opens up making huge spaces like ProPhoto RGB as functional working spaces without roundoff induced posterization (combing of the histogram). This stems from the limited number of colors we can perceive and the fact that 8-bit RGB yields millions of colors while 16-bit RGB yields trillions of colors (a lot more room for roundoff error). Albeit, since I have yet to hear of an output device that can handle the larger gamut of ProPhoto RGB it matters little. Nonetheless, I do all my originals in ProPhoto and convert to output spaces then 8-bit for printing/web.

That said, if you upsize images for printing, then running said calculations in 16-bit color yields notably smoother tonal gradations (i.e., smooth textures remain smooth rather building up noise from roundoff error). Yet, unless you blow images up massively this difference is likely more theoretical than practical due to deviations from the ideal in output devices (think billboards viewed closely or posters at arms reach). Hence, one can clearly see accumulated roundoff error in 8-bit color images at 400% magnification. Hence it means little in practice today. But as output device accuracy, resolution, gamut, and precision improve it may affect a reprint in 5 or 25 years from now.

my $0.02,

Sean

"In the End, we will remember not the words of our enemies, but the silence of our friends."

– Martin Luther King Jr. (1929-1968)

New Website
http://www.envisagement.com/
Last Updated 23 June 2005

How to Master Sharpening in Photoshop

Give your photos a professional finish with sharpening in Photoshop. Learn to enhance details, create contrast, and prepare your images for print, web, and social media.

Related Discussion Topics

Nice and short text about related topics in discussion sections