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Why is CS5 default color mode 8 bit?

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  #1  
Old 07-22-2011, 03:26 PM
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artofretouching artofretouching is offline
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Why is CS5 default color mode 8 bit?

Someone sent my blog a good question. I didn't have a good answer, so I bring it you.

Why does Photoshop make 8-Bit it's default? While it does save the settings if you create a New File with 16-Bit, there does not seem to be anywhere that you can specify "Open All Images in 16-Bit Color Space" in the same way you can specify "Open All Images in Adobe RGB (1998)". Then, if it's in sRGB or 8-Bit, you get a warning dialog box.

Last edited by artofretouching; 07-23-2011 at 10:05 AM.
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Old 07-22-2011, 06:28 PM
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Re: Why is CS5 default color mode 8 bit?

I do not know the answer - but that does not stop me making a guess

I suspect that traditionally many images that find their way into Photoshop have been acquired as 8 bit in the first instance. I am not sure that there is any real advantage in converting from a small colour space to a larger one, so perhaps this may go some way to answering the question.

Many digital cameras however have the ability to shoot in RAW therefore I think it makes a lot more sense to utilise the additional bit depth and import as 16 bit maybe ProPhoto. Once your image is opened in Camera RAW you can specify to be opened as 16 bit in Photoshop, and AFAIK these settings will remain for all images until you make the change to something else.
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Old 07-22-2011, 10:54 PM
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Re: Why is CS5 default color mode 8 bit?

While I was thinking the same thing, the simple fact that I have access to Photoshop shows some signs of "professional" in my title. This does not mean that I am necessarily going to remember to convert some designer's supplied JPG to 16-Bit before fixing it.

So, I guess it just go back to the original question: Why isn't there a "Convert 8-Bit to 16-Bit" option in the preferences? We all know that Photoshop's Preferences are filled with 20+ years of legacy nonsense. No reason they can't, or even shouldn't, add this as an option.
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Old 07-22-2011, 11:31 PM
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Re: Why is CS5 default color mode 8 bit?

Artofretouching, 16 bit is not a color space, it is the bit depth of the pixels in an image. Converting an 8 bit image to 16 bit for all practical purposes is a waste of time, memory, and disk space. An analogy would be that someone started with a number 5.6781 and he / she rounded that number down to 5.0000 and asked you to double it. You now are want your work to be very accurate and so you add decimal places and make the number 5.00000000. Your result is not any more accurate. If you start with a 8 bit file, much of the information contained in a file that was converted from 16 bit to 8 bit has been lost and there is nothing you can do to restore it by converting it back to 16 or 32 bit. You are just adding lots of zeros.
When you are working with RAW files, the software like Adobe Camera RAW, and other programs offer you the option to open or save the files as 16 or 8 bit.
Regards, Murray
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Old 07-23-2011, 01:58 AM
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Re: Why is CS5 default color mode 8 bit?

Hi Artofretouching
Here is a way I suggest trying to have all images you bring into Photoshop to be in 16 bit mode if you really don't want to do the bit depth change manually.

First create an Action whose sole function is to change to 16 bit depth.

Use Edit > Scripts > Scripts Event Manager.....

Set the Open Document event to use your Action to change to 16 bit depth.

With this enabled all images should come in to Photoshop and be converted to 16 bit depth no matter what bit depth they were originally.

I personally don't use this approach because the preferred approach (IMHO) would be to have the user flagged with an option of what bit depth to use similar to mismatches in color spaces. You may not always want "all" images converted to 16 depth.

Murray, you stated:

Quote:
Originally Posted by mistermonday View Post
Converting an 8 bit image to 16 bit for all practical purposes is a waste of time, memory, and disk space
Hmmm, I really appreciate your numerous posts and learn a lot from them yet in this case I respectfully disagree.

Converting a 8 bit image to 16 bit greatly reduces any additional cumulative quantization errors with additional Layer Blends, etc. that would have occurred if you stay in 8 bit mode and proceeded with editing.

Here is an easy example.

I start with an 8 bit image in ProPhoto RGB Color Space where all pixels have R=G=B (gray values with no color) and the image has equal number of pixels at each of the values from 0 to 255. This produces the following histogram:

Screen shot 2011-07-23 at 12.12.29 AM.png

While leaving it in 8 bit mode I change to Lab Color Mode and then back to RGB mode. The updated histogram looks like this:

Screen shot 2011-07-23 at 12.13.22 AM.png

The above roundtrip to Lab Color Mode created an uneven histogram where some values are doubled up and some are not used at all. This type of operation creates the potential for increased banding.

Now, I run a similar experiment where I take the same starting image, convert to 16 bit first, change to Lab Color Mode and then back to RGB mode and then finally convert back to 8 bit mode. Note that the histogram is again perfectly uniform. I have done this with actual images and it produced less banding:

Screen shot 2011-07-23 at 12.14.07 AM.png

Conclusion: better results by converting to 16 bit mode even for 8 bit images. Similar experiments may not be as clean as this yet in all cases I find that you get better results and fewer 8 bit math cumulative errors when converting to 16 bit first.
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Old 07-23-2011, 04:08 AM
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Re: Why is CS5 default color mode 8 bit?

Couple of supplementary questions folks. I'm still using CS3 and note that a number of PS functions are disenabled in 16 bit. Is that still the case with CS5? All my retouching is produced for publicity, ads etc, and has a shelf life of months. Would I gain anything by working in 16bit given the downside of working with larger files. I must say smoother grads has definite appeal.
R.
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Old 07-23-2011, 05:51 AM
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Re: Why is CS5 default color mode 8 bit?

Quote:
Originally Posted by artofretouching View Post
While I was thinking the same thing, the simple fact that I have access to Photoshop shows some signs of "professional" in my title.....
Seems like I have unintentionally caused offence - if this is the case then my apologies. I have to disagree that to have Photoshop shows signs of professional. Early versions of PS are relatively cheap to purchase and the marketing of the application leads many to the conclusion that PS is the only way to go pro or not.

Quote:
So, I guess it just go back to the original question: Why isn't there a "Convert 8-Bit to 16-Bit" option in the preferences?
Perhaps consider asking Adobe themselves either directly or through their forum?

Quote:
We all know that Photoshop's Preferences are filled with 20+ years of legacy nonsense. No reason they can't, or even shouldn't, add this as an option.
Not all of us know, I have to admit I am one of those that is not aware of the so called legacy nonsense, would you care to comment further on this? Who knows your wish for Convert 8 to 16 bit feature may even appear in CS8-10 .
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Old 07-23-2011, 09:13 AM
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Re: Why is CS5 default color mode 8 bit?

Quote:
Originally Posted by John Wheeler View Post
Hi Artofretouching
Murray, you stated:

Converting a 8 bit image to 16 bit greatly reduces any additional cumulative quantization errors with additional Layer Blends, etc. that would have occurred if you stay in 8 bit mode and proceeded with editing.
John, you may notice that I used the word "practical". I am very familiar with quantization error, gaps in histograms, the effects of blendings, levels adjustments, and calculations on 8 bit vs 16 bit images. However, there is a significant difference between the practical and theoretical / mathematical. Your example with LAB is actually a perfect example of my argument. If you read the book LAB COLOR: The Canyon Conundrum by Dan Margulis you will find a very detailed explanation of why.

I personally do all my capture in 14 bit and all subsequent work in 16 and 32 bit and I only convert to 8 bit for output and certain distribution. The problem with starting with an 8 bit jpg image is that it has already been likely compromised (assuming it is not vector or created art). Firstly by truncation to 8 bit and secondly by jpg compression which usually has a much more destructive impact. Yes, conversion to 16 bit may help reduce effects caused subsequent post processing but that will depend a lot on the specific image and what processing is done. But this is a little like applying a coat of lacquer to a car that's just been through a 2 day desert sandstorm.

Today one reads and hears much about the wisdom of working in 16 bit, and that is generally good advise. But we should all be aware that automatically converting every 8 bit jpg to 16 bit is not necessarily a useful practice.

Regards, Murray
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Old 07-23-2011, 10:18 AM
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Re: Why is CS5 default color mode 8 bit?

Quote:
Originally Posted by mistermonday View Post
John, you may notice that I used the word "practical". I am very familiar with quantization error, gaps in histograms, the effects of blendings, levels adjustments, and calculations on 8 bit vs 16 bit images. However, there is a significant difference between the practical and theoretical / mathematical. Your example with LAB is actually a perfect example of my argument. If you read the book LAB COLOR: The Canyon Conundrum by Dan Margulis you will find a very detailed explanation of why.

I personally do all my capture in 14 bit and all subsequent work in 16 and 32 bit and I only convert to 8 bit for output and certain distribution. The problem with starting with an 8 bit jpg image is that it has already been likely compromised (assuming it is not vector or created art). Firstly by truncation to 8 bit and secondly by jpg compression which usually has a much more destructive impact. Yes, conversion to 16 bit may help reduce effects caused subsequent post processing but that will depend a lot on the specific image and what processing is done. But this is a little like applying a coat of lacquer to a car that's just been through a 2 day desert sandstorm.

Today one reads and hears much about the wisdom of working in 16 bit, and that is generally good advise. But we should all be aware that automatically converting every 8 bit jpg to 16 bit is not necessarily a useful practice.

Regards, Murray
I totally agree with what you have stated/quoted. IMHO, if all one is provided and can access is 8 bit images to begin with, converting to 16 bit before additional processing does help make a non ideal situation from getting worse from a practical and not just theoretical standpoint (based on my own practical experience).

Back to the OPs original question. Here is a link for requesting features or reporting bugs:
https://www.adobe.com/cfusion/mmform...&name=wishform

Adobe certainly could provide such features yet as with all businesses they work on a prioritized basis I am sure.

There are certainly features that have an old legacy from within Photoshop that do not have a great need anymore. However, I greatly appreciate that Adobe maintains those features for a backwards compatibility standpoint.

Artofretouching you were not clear if you just wanted that feature or if you wanted alternatives to achieve the same result. I provided one path in a previous post using the Scripts Event Manager. Another approach that works for JPG and TIFF files is to have them open through ACR. Within ACR you can have the defaults set to open up in Photoshop in the desired bit depth and also Color Space. Hope the additional information is helpful.
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  #10  
Old 07-23-2011, 11:00 AM
RobertAsh RobertAsh is offline
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Re: Why is CS5 default color mode 8 bit?

Quote:
Originally Posted by artofretouching View Post
So, I guess it just go back to the original question: Why isn't there a "Convert 8-Bit to 16-Bit" option in the preferences?
There is.

Edit > Color Settings then change your Working Spaces > RGB to ProPhotoRGB. Then set your Camera Raw import options the way John describes above.

You can also do Image > Mode and set your working color space to 16-bit on a case by case basis.

Quote:
Originally Posted by artofretouching View Post
We all know that Photoshop's Preferences are filled with 20+ years of legacy nonsense. No reason they can't, or even shouldn't, add this as an option.
Quote:
Originally Posted by Tony W View Post
Not all of us know, I have to admit I am one of those that is not aware of the so called legacy nonsense, would you care to comment further on this? Who knows your wish for Convert 8 to 16 bit feature may even appear in CS8-10 .
Well, actually there is such legacy stuff. It wasn't nonsense at the time, nor is a good bit of it nonsense now -- if you're in pre-press, which is what Photoshop was originally designed for doing. Photoshop morphed into a photographer's tool later in its life but didn't start that way.

One example is this very 8-bit vs 16-bit default that we're discussing. That might make sense for Elements, but not for Photoshop proper. AdobeRGB 16-bit should be the default, if not ProPhoto RGB.

Another example is Photoshop's memory handling. After a horrendously painful time with file I/O at 8 GB RAM I upgraded to 16 GB RAM. That helps a tremendous amount overall, but Photoshop still caches several GB of data on disk when there are enough GB free in RAM to store it there. I allow Photoshop 70% of my RAM but it still prefers to store too much on disk, which makes it much slower to read when it needs to be read into memory.

There are other areas, too, like most of the "secret" and "professional" performance-enhancing settings we all read about and/or take for granted that we have to do manually and do them that way without really thinking about it, we just know they have to be set. A lot of those settings should be default in Photoshop proper.

Last edited by RobertAsh; 07-23-2011 at 03:19 PM.
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