sRGB or Adobe RGB

[Mike Hollingshead]

How do you do your image workflow? I've known Adobe has the larger gamut and have mostly gone with that. But the more I do things and read, the more confused I get.

Monitors don't show in Adobe RGB but use sRGB....so obviously when one is done with the image it needs converted to sRGB for web.

Now I'm reading more and more that most printers do better with sRGB!

Ken Rockwell says just use sRGB... http://www.kenrockwell.com/tech/adobe-rgb.htm Still not sure what I think about most of his "advice"...but there that is.

I'm only fussing over this again as I was working on some images and noticed something. My shadows seemed to be going black before they should. 0 is the value for black while 255 is white. One a monitor testing site I could see the shade difference for shadows at 2 or 3 for sure which is good and very close to black. That was in a browser. So what I decided to do was paint the 15/15/15 shade on 0/0/0(black). In photoshop I could make out the difference between that and 0/black just about as well as I could 3/3/3/ and black in the browser. 15/15/15 in there was nothing near what it was in the browser. I wound up assigning the sRGB profile instead and bam, shadows opened up in there closer to how they should be. Still not sure if there should be this big of a difference in shadow lightness between the two color spaces. All I know is it's hard to tone things in Adobe RGB in there and keep the shadows away from looking black, even when they aren't touching the left side of the histogram.

Seeming more and more like a waste of time to mess with Adobe RGB.

I've learned it doesn't seem to matter what you assign your camera to shoot in if you are doing it in RAW...it's just tagging the file and not doing anything bad. But of course other posts online say otherwise, but not really buying those.

Thoughts? Workflows? I guess the obvious "best" workflow is pretty easy to see being the bigger gamut. It's just getting highly annoying seeing the shadows go black sooner than they should.

Edit: Just came across this fairly nice/broad easily to follow article. http://www.smugmug.com/help/srgb-versus-adobe-rgb-1998

This quote makes me think sRGB better for storms with the gradient thing.


However, Adobe 98 is broader, meaning it spreads its crayons across a broader range of colors by making the jump between each color more coarse.
You get finer increments of skin tone by using sRGB, for example. But the pure cyan in HP's original logo can only be accurately represented by Adobe 98, whereas in sRGB you would have to pick a substitute color.


That link also suggests it does indeed matter what you set your camera to, even in RAW. I think maybe it was just written a little poorly and they are saying it captures in RAW and there's no reason to go to Adobe RGB in camera IF you are saving as jpg or tiff with the camera. Or maybe they are saying it affects the RAW file more than just tagging it for conversion later.

[James Langford]

This is something I've gone around and around on for several years. I currently use sRGB, but have been thinking of changing to Adobe. My printer uses sRGB exclusively, so that has been my main driver behind staying with it. However, as you stated, Adobe has a wider gamut of colors. Also, it seems that more and more printers now offer Adobe support.

My biggest question is how much of a difference would Adobe make in the final output of my work? Is it anything that I or anyone else would ever notice, or is it a measurebator type of thing?

Ultimately, my thinking is starting to shift to this: Adobe gives me more range, and I can easily change to sRGB is post processing. Having the original in Adobe at least gives me the option sometime down the road of revisiting my work and reprocessing to take advantage of Adobe.

Just my 2 cents,

James

[Ryan McGinnis]

Mike -- you shoot stock, so the answer should be "aRGB". (I'll reply to your email soon; been out of town :)). Most creative clients who print on a printing press will prefer aRGB images over sRGB.

If you are printing fine art prints, then go with whichever format your printer or lab prefers.

The neat thing about aRGB is that you can always convert it to sRGB for fine art prints if you have to. However, converting sRGB to aRGB does nothing. It's not a perfect anaology, but it's similar to converting from 16bit color to 8 bit color. You can always go from 16 to 8, but going from 8 to 16 does nothing. 16 just holds more info. aRGB holds more color info.

There are actually some color spaces that hold even more color info than aRGB, but they don't seem too widespread at the moment.

*edit* I should mention that for web use, you should ALWAYS use sRGB. Very few browsers (only Safari and, with plugin Firefox) properly display aRGB images -- meaning that most aRGB images on the web look muted and lackluster in most browsers.

[Mike Hollingshead]

Thanks for the thoughts. It really can be a head spinning deal to try and understand all the various ins and outs to color management.

Camera color space to shoot in(adobe RGB I guess), Photoshop working space(needs to be same as the image profile), output space or profile which 99% of the time sounds like it will be sRBG. I've sold images enough times now and have never once been asked to send it in adobe RGB instead of sRGB. That article makes it sound like the far majority of printers don't even want Adobe RGB. Yet it sounds like maybe at some point there will be someone that wants/needs it in Adobe RGB.

Then there is the whole convert to profile vs assign profile. So I guess I will plan to shoot in Adobe RGB like I have and keep them in Adobe RGB as far as keeping stock image files processed and ready on the pc. Then when I go to make one ready for printing(they'll want sRGB here in town...and if I have it in Adobe RGB it will be muted) I will have to convert to sRGB profile and not just assign. But once I do that won't I have to change photoshop's working space over to sRGB now? I guess converting is supposed to keep it looking like it did in the other space, so it actually changes the data not just tags it. At least saving as for web gives a preview I guess.

Now I'm stumbling onto something relating back to that whole dark shadows issue. Took an Adobe RGB file and converted it over to sRGB. While it was still Adobe RGB the dark wing tips to the geese looked near or full black....yet the histogram did not have the info slid over all the way to the left. That has been my biggest issue and what has got me looking all into this crap again. If I process that as Adobe RGB blacks look clipped before the histogram says they should. So anyway, I just converted that to sRGB(converting keeps it looking the same) and it looks the same but the histogram slid left...now making more sense to what those blacks had been looking like. This is a pretty annoying deal trying to tone things in Adobe RGB and having the histogram info not near the left side but things looking black anyway. Hrrrmmm. Still lost on this aspect.

[Ryan McGinnis]

Well, actually, since you shoot raw it doesn't really matter what colorspace you set it to in the camera -- that only comes into play if the image is being converted to a JPEG by the camera itself. RAW files have no color space -- they're literally a raw dump of the pixel data of the sensor. Color profile is not assigned until you use a RAW converter to turn the RAW file into a normal TIFF or JPG. At that point you can pick pretty much anything. I think Pro RGB (http://www.outbackphoto.com/color_management/cm_06/essay.html) is the widest gamut you can pick (therefore retaining the most color info). But most clients have no idea what Pro RGB is, so they'll probably want Adobe RGB. (Not to mention that ProRGB requires that it only be saved as a 16 bit TIFF, which many clients will think is overboard, unless you're sending them images via hard drive in the mail or something.)

To be fair, most printing press clients will prefer AdobeRGB, but they won't really blow a gasket if they get an sRGB instead. I doubt you'll ever lose a sale over it, anyway -- people are coming to you for your images because they're damned rare and hard to get, and because you capture storms in a way that blows peoples' minds. But it's true that if you hand a client an aRGB file, most of the time it will make them (or at least their pre-press department) happy. And I know many of the stock agencies reccomend aRGB files, if possible.

Generally, it's best to never just assign a profile unless the image has no profile or it's tagged with the wrong profile. If you are assigning images with one color space into a new color space, this may explain why you are getting weird histograms. (If you want to go from one color space to another, you need to "convert". Of course, converting slightly degrades color information, but it's not something matters most of the time.) You should generally "use the embedded profile instead of the color space" if asked.

At any rate, the histogram is usually what you're after. If it looks black on your monitor but the histogram says otherwise, trust the histogram before you trust your monitor.

[James Langford]

[quote=Ryan McGinnis;225808]Well, actually, since you shoot raw it doesn't really matter what colorspace you set it to in the camera -- that only comes into play if the image is being converted to a JPEG by the camera itself. quote]

Ah, I didn't realize that. That's good to know, since I shoot exclusively in RAW now. :) It seems like I'd heard that even with RAW, the colorspace is set by the camera. Makes more sense being the other way, though. Thanks for clearing that up!

James

[Stephen Locke]

I edit in ProPhoto RGB 16 bit. I would not convert to a smaller space (throw away information) until the image is ready to deliver to the web. Color management from device to device is important and has more to do than just color space. I found it worthwhile to attend a seminar, $250, to get educated on this stuff.

I have not seen this video but I expect it would be worth the money for someone who has not yet immersed themselves into color management between devices.

http://www.luminous-landscape.com/videos/camera-print.shtml

[Stephen Locke]

Suprised you struggle with this Mike. The dynamic range of your stuff amazes me. I'm always looking at it saying how the hell did he hold the values in both the shadows and the sunlit sky. I keep saying to myself, "Looks like it was illuminated by the Gods".

[Mike Hollingshead]

At any rate, the histogram is usually what you're after. If it looks black on your monitor but the histogram says otherwise, trust the histogram before you trust your monitor.


It turns out the whole changing lightness was from assigning and not converting. But I still have the other thing with the changing histogram/shadow issues. If I convert from Adobe RGB to sRGB the histogram takes my non clipped shadows left and clips them.

So here lies the problem with trusting the histogram. I trust it in Adobe RGB, they look black when they shouldn't quite be as the histogram has them slightly right of the left edge. So I save it like that trusting the histogram is right(it has to be). But the second I convert that to sRGB the histogram moves left showing them clipping on the left just like they appeared to be doing visually. So I don't get how I can trust the histogram in Adobe RGB.

Here is what I'm saying if this makes no sense. Download this file and open it in PS then convert it to sRGB and watch the shadows on the histogram... http://www.extremeinstability.com/stormpics/2009/09-9165.tif They jump left on there but of course not in the image. Not a huge deal on that till you start working on the same picture larger. The grey to black wing tips look more just black. Now to me the sRGB's histogram looks like I'd expect it to since the shadows look so black. Maybe an easier question to ask is why such a big jump on the histogram lightness converting when there is zero visual change.

[Ryan McGinnis]

It turns out the whole changing lightness was from assigning and not converting. But I still have the other thing with the changing histogram/shadow issues. If I convert from Adobe RGB to sRGB the histogram takes my non clipped shadows left and clips them.

So here lies the problem with trusting the histogram. I trust it in Adobe RGB, they look black when they shouldn't quite be as the histogram has them slightly right of the left edge. So I save it like that trusting the histogram is right(it has to be). But the second I convert that to sRGB the histogram moves left showing them clipping on the left just like they appeared to be doing visually. So I don't get how I can trust the histogram in Adobe RGB.

Here is what I'm saying if this makes no sense. Download this file and open it in PS then convert it to sRGB and watch the shadows on the histogram... http://www.extremeinstability.com/stormpics/2009/09-9165.tif They jump left on there but of course not in the image. Not a huge deal on that till you start working on the same picture larger. The grey to black wing tips look more just black. Now to me the sRGB's histogram looks like I'd expect it to since the shadows look so black. Maybe an easier question to ask is why such a big jump on the histogram lightness converting when there is zero visual change.

I could be wrong, but I think this is just an issue of Adobe RGB having more colorspace to work with than sRGB. That is, Adobe RGB can have more "near black" colors than sRGB; you convert to sRGB and some of those very-near-black colors go black and the histogram gets slightly expanded. But the effect is usually very subtle; I doubt you'd lose much detail that would be perceiveable on the web (which is the ultimate reason to go to sRGB) even with a full sized file at 100% crop.

What I guess I mean is that you're kinda stuck with this sort of thing when you convert from wider profile to narrower profile; you're trying to dump a gallon bucket of color into a three-quart bucket. Some of the color information gets lost, and unfortunately some of those are the colors that are in the near-total-black shadow areas. The histogram seems a bit more spread out because you're essentially expanding it by giving it less color room to work with. The image you see on your screen doesn't change much because your screen isn't anywhere near capable of showing all the colors that aRGB has available, so the conversion doesn't really change anything visually. On the other hand, were you to get a nice inkjet and print two photos, one of that shot in aRGB and one in sRGB, you'd probably notice more shadow detail in those black wingtips in the aRGB-sourced print than in the sRGB-sourced print, even though they'd both look the same on your screen. (Though you'd probably need a magnifying glass and would get a headache from staring in order to see the difference in the shadows. :)) Actually, what you'd really notice most of all is (depending on the image) that the aRGB photo would have more color detail overall.

[Darren Addy]

Mike, are you happy with your monitor? Has it gotten out of calibration? I realize that an 8-bit monitor can't display 10-bit, 12-bit, or 16-bit color properly, but you should see a good interpolation/representation of what is there. Maybe an upgrade in the monitor or your calibration procedure is what you really need?

In the colorspace discussion, I'm planning on learning post-processing in the LAB colorspace. It is the biggest colorspace of all (so not throwing away any info until you are ready to convert) and you can adjust the color channels completely independently. This well-regarded book by Dan Margulis explains this little known colorspace and how to use it in digital photography post-processing:

Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace
http://www.amazon.com/Photoshop-LAB-Color-Adventures-Colorspace/dp/0321356780/

[Mike Hollingshead]

No, it's not a monitor issue at all.

http://www.drycreekphoto.com/Learn/Calibration/monitor_black.htm

I can see the difference by 2/2/2 barely and for sure 3/3/3.

It's really simply the histogram difference between Adobe RGB and sRGB that bugs me. If you adjust in Adobe RGB setting black points in levels...you can be sure to be clipping those once you convert to sRGB...and they even look that way to you while the Adobe RGB histogram suggests they shouldn't. It's not a huge killer on most images, but it sure is with these geese lol. Like that article said you get more gradiations to colors in sRGB while you get more colors in Adobe RGB.

I'm starting to come to the conclusion to use both, which would just get too confusing with a bunch of images. All the larger dynamic range images may prove better with sRGB.

I appreciate all the info. I'm a little more clear about it all, but just as confused on what route I'll take, lol.

[Darren Addy]

Interesting article with a comparison of some histograms for the various color spaces: http://www.oreillynet.com/digitalmedia/blog/2007/08/lightroom_color_spaces_1.html

Excerpt:
Most DSLR’s produce colors that are outside of the standard Adobe RGB color space even though you have your camera set to Adobe RGB. Hence for the highest image quality in a raw processor one would use the ProPhoto RGB color space. I highly recommend that folks use the ProPhoto RGB color space when exporting images out of Lightroom and as their archival color mode - then in Photoshop one can convert the color space to whatever is needed for output and have a lot more control.Workflow suggested seems to be: Camera -> Lightroom (archive) -> Photoshop -> ( output-specific correction in whatever form and colorspace)

Also, my prime suspect in Mike's shadow problem is a mismatch between monitor and colorspace gamma, but I don't know enough to prove it yet. EDIT: I take it back. Your colorspace gamma is 2.2 and your monitor is probably 2.2 also, unless you changed it.

Also found this clear explanation/visualization of both colorspaces and gamma which helps me visualize things a little better:
http://www.betterlight.com/downloads/conference06_notes/what_color_space.pdf

[Mike Hollingshead]

Some good links on ProPhoto RGB. Sounds huge, given it encompasses colors we can't even see....but?

http://www.luminous-landscape.com/tutorials/prophoto-rgb.shtml

http://www.earthboundlight.com/phototips/prophoto-rgb.html

By converting your RAW files into ProPhoto RGB in Adobe Camera Raw you preserve more of what the sensor actually saw. Once you open them in Photoshop though, you need to decide what to do next. If you keep them in ProPhoto, you'll have files that in the future may yield better prints than if you settled for Adobe RGB. But the gamut of ProPhoto is so large that, unless you are careful, you may need to contend with banding and other artifact problems, even in 16-bit mode. A definite dilemma.Then this from the link on that same page....

This may seem an esoteric "feature" at first, but it does have real world consequences. It's not at all uncommon to convert between working spaces for instance. I've done it myself countless times. Open a raw file into ProPhoto RGB, and then later convert to Adobe RGB for instance. If you select Perceptual rendering intent in order to avoid banding issues, you'll get Relative Colorimetric anyway along with its tendency to cause banding at the edges of the target gamut when going from a big color space to a smaller one. You probably won't realize since very few monitors themselves have a wide enough gamut to see the problem. Not good.
http://blogs.oreilly.com/lightroom/2007/12/the-argument-for-a-prophoto-rg.html

This quote from the above link.

If you are going to be exporting into the sRGB color space from Lightroom leave some room on either side of the histogram to account for the clipping on either end that will occur. If you want to dial your images in so that they look exactly as you want and the colors won’t shift then always export to the ProPhoto RGB color space and “convert to profile” in Photoshop where you have some control of how the conversion process works.That is exactly what I was seeing the histogram do converting to sRGB. It just bugs me how in adobe RGB it visually looks black before it does on the histogram.

Hmm then I read this...

Maybe in the preferences a color space could be chosen just like in Adobe Camera Raw. This would then adjust the histogram for whichever color space is chosen so images could be dialed in perfectly with no color shift on export.Now I wonder if there is a way to do this in camera RAW without this issue I'm seeing.

One last link.

http://www.outbackphoto.com/color_management/cm_06/essay.html

Overall my head is now annoyed lol. The potential banding issues down converting from ProPhoto RGB are causing me some concern. I'm processing/reprocessing 600 or so stock images lol. I'm really wanting to get this right. Too bad there's really zero clear cut choice. I sort of wish I was as dumb as I was before looking more into it. I doubt I'd ever notice, but now I know enough to wonder about crap.

It gets confusing when you realize 16 bits is the same amount of info, but somehow there are these much larger color spaces in the same size. I'm sort of like, how do you mix R/G/B with the same amount of incriments and get such a bigger range of colors. Then all this out of gamut stuff and rendering intent stuff....what papers can even show....monitors can even show.....cameras can actually capture....eyes can even see.......aaarrrrggghhhh. All for something I'd nearly certainly never see the difference of. I feel like that younger dude on Shawshank Redemtion after he took the test. "#$@#$@$"

Time to go black and white. Colors are quickly becoming overrated.

[Stephen Locke]

Time to go black and white. Colors are quickly becoming overrated.

I did (go black and white). Life does not get easier when you handicap yourself by doing that. A whole new set of problems emerge. In the absence of colour it is more difficult to produce an evocative image. One abandons colour and begins to concentrate on local and global contrast. Pushing contrast also emphasises noise. So now you are playing the problem of noise against the desire to spread the grayscale. And, banding issues do not go away! Banding gets worse as you push contrast. So, I often end up saying the opposite of your quote above. "Time to go colour, black and white is overrated!". I'm still dealing with all the same issues and more. Still working in the largest color space possible at any given time.

To make things even more surreal I've heard it said that colour digital images
are actually black and white . . . the digital realm being a world of 1's and 0's, Yes's and no's. Black vs. White.

[David Schuttler]

Hey Mike, be glad you're not adding in being partly color blind also. Many times I'm not sure what my pictures might look like to others.

[Darren Addy]

This is a confusing issue, I'll give you that. I think there is learning what is better (Best Practices, if you will) and then there is cost/time/benefit analysis (is it worth the extra hassle?)

People can be divided into two basic camps: those that get educated and those that won't/don't. If you don't get educated you can't really move to the next step of deciding if it is worth it.

People who move to the next level will then be divided into at least two camps: Those who feel the extra time/care is worth it and those that don't. Part of that may be dependent upon the equipment that they have.

For example, I think everybody would agree that it is better to keep as much information in the digital file as possible and converting to a lossier format copy only when needed for a specific purpose. That means shooting in RAW in the camera and using ProPhoto RGB in your RAW converter and Photoshop workflows. The reason is pretty simple (i think): ProPhoto RGB is 16-bit, while Adobe RGB and sRGB are only 8-bit. From the link Mike shared above: Using ProPhoto space is easy. In your raw converter, either output your files into Photoshop tagged with the camera's profile if you're using Capture One, or tagged with in the ProPhoto colour space if you're using Camera Raw. (ProPhoto RGB is Camera Raw's native colour space). When using other raw converters it will depend at the converter's capabilities.Now why would you want to use a huge color space when your camera limits you to a smaller one? I think it comes down to remembering that computers (software and hardware) treat everything like a number. Imagine that you have a calculator that can only DISPLAY whole numbers. If you input a problem like 9 divided by 2, we know the answer is 4.5, but your calculator has to choose between 4 and 5 for the answer. It doesn't do this randomly, but follows a set of algorithms (in this case probably rounding up to 5). The point is that either answer is not precisely the one you wanted/needed. The same is true with colors. If your software is trying to determine how to render a particular pixel, it will be doing it with an algorithm that takes into account the color information of the pixels around it. If you are working in ProPhoto RGB space in your editing program, you have (in effect) more decimal places to work with and thus a more precise result in the math that determines that pixel's color. The more accurate that is, the more accurate the output will be when it "rounds down/up" to a smaller color space.

While it would be NICE if you could see these differences on your screen, just because you can't see them on your screen does not mean they are useless. It means that you will have a more precise "mathematical definition" of your digital image WHEN THE TIME COMES to round down to sRGB (for example). It is then that you might see a difference, but that is when it counts.

Now back to the original question of Adobe RGB vs sRGB:
Using the same logic as that above, it would be preferable to have as much color information as possible... so theoretically Adobe RGB would be the best choice for in-camera. Again, it would be great to be able to SEE that
difference in your correction process. But I don't think you will/can unless you get a "wide gamut" monitor (and calibrate it properly) AND your operating system (and software application) supports that "wide gamut".

From what I've read, it sounds like this is where Vista is better than XP (with XP you are out of luck on wide gamut) and where Windows 7 will be even better.

As far as workflow is concerned (Camera RAW/Photoshop), it seems that a lot of photographers "live in" ProPhoto RGB in 16 bit mode and convert to AdobeRGB 8 bit when sending to a pro printer and, of course, convert to sRGB for web use.

Interestingly, new browsers like Firefox 3.5 will take into account an embedded color profile (which I think means that if the user is on an operating system that supports it, and their monitor supports it, they will see a better image than Joe User on XP with IE. This may not be important to most people, but I wonder if there are sophisticated Photo Editors/stock photography buyers out there that will be looking for images to purchase using such a set up. If so, this means that a photographer that takes the time to incorporate this into their workflow will have noticably better looking images (to user with that set-up combination) and therefore an edge. It may even become a way for buyers to further separate the Men from the Boys (pardon my sexist language).

The downside of this is that a web image with an embedded color profile is going to be a larger file size (and thus a slower download) than one without it.

PS... this is a great explanation of Color Spaces and Calibration, for those who are (still?) confused:
http://digiichi.pentax.jp/english/tech/vol_39.html

[Mike Hollingshead]

Not sure about this whole pro photo rgb is 16 bit and adobe rgb is 8 bit thing. I don't think the spaces are bit-depth defined. In fact this was a drawback to prophoto RGB, sure it's bigger/wider....but you have the same amount of info to describe it as the others/aRGB/sRGB. So you have further out colors, but then bigger gaps are required between them. So if you want/need highly smooth gradients the wider gamuts might not be the best choice. The box of crayons thing was the best way to think about it. They all have a box of 64 colors(figuratively speaking) to describe the space. This is why some places I read suggested one might want to work in 32 bit when using ProPhotoRGB.

I now have a 102% adobeRGB monitor. The greens and red are rather amazing. But after a while of using it, I don't know that even adobeRGB is all that much "greater". The best thing I like now is the resolution of the thing, at 1920x1280 or something. I now just make sure I'm working in Adobe from the get go, at 16 bit of course.

[Darren Addy]

The difference between 8 and 16 bit per channel

http://www.artemis-design.com/difference-between-8-and-16-bit-per-channel.html

[Mike Hollingshead]

The difference between 8 and 16 bit per channel

http://www.artemis-design.com/difference-between-8-and-16-bit-per-channel.html


Yes, but where were you reading that part about ProPhotoRGB is 16 bit while AdobeRGB is 8. I wasn't saying anything about bit depth, just that I didn't think the color spaces were bit depth "set" like you had mentioned them being.

ProPhoto RGB is 16-bit, while Adobe RGB and sRGB are only 8-bit.

[Darren Addy]

I've been reading so much stuff on this, I don't remember where I got the ProPhoto is 16 bit while the others are 8 bit. But after reading a few more articles, I see that any color space can be used in 8 bit or 16 bit mode, so I stand corrected on that point.

However, while you could do sRGB in 8 bit:
don't even think of using ProPhoto RGB in 8-bit mode.- source: http://www.earthboundlight.com/phototips/prophoto-rgb.html

The link above also explains the benefits of the larger color space by showing you how both Adobe RGB and sRGB actually CLIP the capabilities of the Epson printer. With either of them you don't get colors that the printer could deliver. That's only important if your original scene contained those colors, of course, but it illustrates the real world benefit of the larger color space.

Other articles from the same source are also illuminating:
The Great sRGB Versus Adobe RGB Debate
http://www.earthboundlight.com/phototips/srgb-versus-adobe-rgb-debate.html
and
More Than a Bit of a Difference: 8-bit Versus 16-bit
http://www.earthboundlight.com/phototips/8bit-versus-16bit-difference.html

As a side point, this Adobe forum thread (http://forums.adobe.com/thread/369621) is very educational regarding the difference between assign and convert. And the guys in that forum all say that the way to enlightenment on color management begins here (http://www.gballard.net/psd/cmstheory.html).