largest color space

chrisjlee

My friend and I were discussing color spaces. We were curious what is the largest color space currently existing?

Isn't it Adobe RGB (1998)

jfriend

Color space musings...

chrisjlee wrote:

My friend and I were discussing color spaces. We were curious what is the largest color space currently existing?

Isn't it Adobe RGB (1998)

AdobeRGB is a larger color space than sRGB. Pro PhotoRGB is even larger than AdobeRGB. But, the LAB color space is even larger than both of those. Here's a graphical depiction of various color spaces.

One thing that's unique about LAB is that it can represent extremely bright colors (because Luminosity is completely separate from color so you can have max brightness and still have color) while all xRGB color spaces are forced to turn things white when they get really bright.

While you can work in LAB in Photoshop, you can't usually capture images in LAB, so if the question is what color space should you capture the image in, LAB usually isn't a choice.

When debating the merits of larger color spaces, there are pluses and minuses to larger color spaces. I once read something that made sense to me: "The best color space for any particular job is the one that just fully contains the colors without anything out of gamut and with minimum unused range".

What this means is that a really large color space used on an image that doesn't need the full range of the large color space will just cause compression of colors on the inside of the color space. When you aren't using the full range of the color space, you are then using a smaller range of numbers to express the colors you have in your image, thus not representing as much color detail as could be expressed in a color space that fits your image better. Said differently, a larger color space is only better than a smaller one when you actually need the larger range.

Also, ALL images are eventually going to be viewed through the limitations of some output device (screen, printer, etc...). Since so many of those devices have smaller color spaces, you might not be able to take advantage of capturing colors that are larger than the output device.

chrisjlee

Thanks. that was very helpful.

Shay Stephens

I shoot in the same color space as my output device, sRGB. I don't care what has the largest or smallest color space since my output device can't render that anyway.

But it might make for a fun bet over beer :-)

pathfinder

I believe, ProPhoto is the native color space of the DSLR's sensors, so theoretically that is the largest space to capture data at the time of exposure. But I import from RAW to PS in 16Bit sRGB.

Margulis, and others, says 8 bit is usually enough, but my computer doesn't whine with the 16 bit images so I don't go to 8 bit until saving my final jpg for the web or printing in sRGB.

I also save a final psd in either 8 or 16 bit as the image moves me:): again in sRGB. I quit using Adobe RGB entirely - because I do not submit files to printing presses. If you shoot for pre-press work, then ask the printers what color space and file type they need. They'll tell you.

luke_church

pathfinder wrote:

I believe, ProPhoto is the native color space of the DSLR's sensors, so theoretically that is the largest space to capture data at the time of exposure.

Interesting. Can I ask why do you think that ProPhoto is the native colour space of the sensors? I guess it could be the space of the output format, coupled with the filters, but their sensitivity is way beyond that colour space, just in a nice, helpfull, non-linear space that then gets mangled...

Margulis, and others, says 8 bit is usually enough

I was discussing this with someone recently. Is their argument related to the simulataneous photoic perception of the vision system? The conclusion that (I think) we came to was that 8 bits was usually adequate, but if you wanted to strech the colour range to correct for the likes of exposure issues, or artisitic reasons then a greater bit depth was better, simply due to the quantization issues. I guess it would have to be fairly extreme before the extra 4 bits from the camera was really any use.

Equally if I understand things correctly its likely to be more important for reds and greens than blues?

Again, this is a new world that I'm working on understanding, am I talking rubbish?

but my computer doesn't whine with the 16 bit images so I don't go to 8 bit until saving my final jpg for the web or printing in sRGB.

Likewise.

Interesting stuff this colour,

Luke

Mike Lane

jfriend wrote:

AdobeRGB is a larger color space than sRGB. Pro PhotoRGB is even larger than AdobeRGB. But, the LAB color space is even larger than both of those. Here's a graphical depiction of various color spaces.

Correct me if I'm wrong, but wouldn't aRGB and sRGB be exactly the same size since they are both 8 bit but cover different areas of the spectrum? If I've got 16.7 million crayons, I've got 16.7 million crayons. So one box has aquamarine and one has bluegreen, they still have 16.7 million of them.

Prophoto RGB would have substantially more since it is a true 16 bit colorspace.

cletus

Mike Lane wrote:

Correct me if I'm wrong, but wouldn't aRGB and sRGB be exactly the same size since they are both 8 bit but cover different areas of the spectrum? If I've got 16.7 million crayons, I've got 16.7 million crayons. So one box has aquamarine and one has bluegreen, they still have 16.7 million of them.

Prophoto RGB would have substantially more since it is a true 16 bit colorspace.

It don't make sense does it???

I don't know the why, but I'm pretty sure adobeRGB does cover more space than sRGB.

Mike Lane

cletus wrote:

It don't make sense does it???

I don't know the why, but I'm pretty sure adobeRGB does cover more space than sRGB.

I suppose it depends on what you mean by size. You could have 8 bits per channel of only green hues. 16.7 million green hues and it'd be a tiny little dot on those pretty graphical color space displays. I bet you that if you got someone with a Ph.D. in mathematics with a specialty in topology, they could come in here and explain why the aRGB triangle is the exact same size as the sRGB triangle even though it looks bigger.

jfriend

Breadth of gamut, not number of crayons

Mike Lane wrote:

Correct me if I'm wrong, but wouldn't aRGB and sRGB be exactly the same size since they are both 8 bit but cover different areas of the spectrum? If I've got 16.7 million crayons, I've got 16.7 million crayons. So one box has aquamarine and one has bluegreen, they still have 16.7 million of them.

Prophoto RGB would have substantially more since it is a true 16 bit colorspace.

The term "size" of a color space usually refers to the breadth of colors that the color space covers (see these graphs), not the number of crayons within that breadth. I was commenting on the breadth of the color space. The number of crayons issue is the classic 8-bit vs 16-bit issue about which lots and lots has been written. No matter how many crayons you have, if the color space doesn't have the right red colors in it to make the red rose come out looking life-like, then you need a bigger color space that covers the reds you need.

sRGB and AdobeRGB can be used with 16-bit images too, so you can have zillions of crayons in those color spaces if that is more important for a particular image.

jfriend

It's a bit of a trade-off

cletus wrote:

It don't make sense does it???

I don't know the why, but I'm pretty sure adobeRGB does cover more space than sRGB.

AdobeRGB includes a broader range of colors than sRGB does. If you look at the graph here: http://www.dynamicartwork.com/articles/gamuts, you can see that AdobeRGB includes more greens and a few more blues (look at the range of colors inside the black triangle).

If you are comparing AdobeRGB and sRGB at the same bit-depth (e.g. same number of crayons), then AdobeRGB crayons are spaced further apart than sRGB crayons. That's why this is a trade-off. If you don't really need the additional colors that AdobeRGB covers, then you may actually get a better image with sRGB because it's crayons are closer together for the colors that you do have in your image, thus giving you finer color granularity (though some would argue, you can't tell the difference). If, on the other hand, your image does include colors outside the sRGB colorspace and those are important to your image, then AdobeRGB may produce a better image if those colors will survive all the way to your final output device.

cletus

jfriend wrote:

AdobeRGB includes a broader range of colors than sRGB does. If you look at the graph here: http://www.dynamicartwork.com/articles/gamuts, you can see that AdobeRGB includes more greens and a few more blues (look at the range of colors inside the black triangle).

If you are comparing AdobeRGB and sRGB at the same bit-depth (e.g. same number of crayons), then AdobeRGB crayons are spaced further apart than sRGB crayons. That's why this is a trade-off. If you don't really need the additional colors that AdobeRGB covers, then you may actually get a better image with sRGB because it's crayons are closer together for the colors that you do have in your image, thus giving you finer color granularity (though some would argue, you can't tell the difference). If, on the other hand, your image does include colors outside the sRGB colorspace and those are important to your image, then AdobeRGB may produce a better image if those colors will survive all the way to your final output device.

That clears it up!

Thanks!

jfriend

DLSR sensors have their own (non-standard) color space

pathfinder wrote:

I believe, ProPhoto is the native color space of the DSLR's sensors, so theoretically that is the largest space to capture data at the time of exposure. But I import from RAW to PS in 16Bit sRGB.

Digital sensors have their own color space that would usually not match any existing standard. It varies according to the design of the sensor, it's filters, micro-lenses and other technical parameters.

The job of a RAW processing program (ACR, Bibble, Nikon Capture, Aperture, etc...) is to know what the color profile of the sensor is and convert it to one of the known standards so the image can be used in other programs.

pathfinder

jfriend wrote:

Digital sensors have their own color space that would usually not match any existing standard. It varies according to the design of the sensor, it's filters, micro-lenses and other technical parameters.

The job of a RAW processing program (ACR, Bibble, Nikon Capture, Aperture, etc...) is to know what the color profile of the sensor is and convert it to one of the known standards so the image can be used in other programs.

You are correct and I mis-stated that ProPhoto was the color space of the sensor. The details of the sensors are probably not published, and proprietary.

Actually, Pro Photo is the color space that the RAW file data is brought into in Adobe Raw Convertor,, and then converted to aRGB or sRGB or whatever on being passed into Photoshop.

Pro Photo is very, large 16 bit gamut that "encompasses all the colors we can capture with the sensor, and the vast majority of the colors we can see" stated Bruce Fraser in Real World Camera RAW for PSCS2.

I read that book for PSCS a couple of years ago, and got my definition of Pro Photo slightly askew. Sorry, for any confusion about my statement.

Fraser goes on to say that "if you see serious color clipping on a conversion to Pro Photo RGB, you're capturing something other than visible light!"

In researching Pro Photo this afternoon to respond to jfriend, I came across an article about the Pro Photo color space on the outbackphoto.com that went on to explain Rendering Intents that I found quite helpful.

Rendering Intents are how the printing drivers in Photoshop deal with colors that are in the file and cannot be printed in CMYK on paper because they are unable to be printed with CMYK ink. This gets to a question earlier asked about highly saturated web images and the prints one would purchase that cannot match the highly saturated web image pixel topixel. Rendering Intents attempt to solve this problem.. You've all seen Rendering Intents when setting up your print profiles for PSCS2.

PERCEPTUAL - compresses the colors in the wider source space to the print space by compressing ALL the range of colors so they will fit in the CMYK space on paper. The overall appearance is unchanged, but we have no control over the algorithm used and in-gamut colors can be changed quite a bit.

ABSOLUTE COLORIMETRIC - Prints in-gamut colrs dead on, and clips out of gamut colors to within gamut and prints all out of gamut colors as the boundary of the in gamut colors. This results in flat looking areas with coarse tonal gradations.

RELATIVE COLORIMETRIC - Rel Colorimetric scales the white point of the source image to match the white point of the target space. Thus all the colors see to have the same hue relative to white even though they are not exactly the same colors. Out of gamut tones are then displayed as the nearest boundary tones of color.

SATURATION - Converts saturated simple colors in the source space to the same saturated basic colors in the print space. It ignores diffeences in hue and lightness, so it is much better for simple graphics with basic colors, than reproducing photographs.

The short answer is that perceptual or Relative Colorimetric are the preferred choices that shoe horn out out of gamut images into something that can be sprayed onto paper and look like we saw them on the screen, or at least,a reasonable facsimile thereof.


Here is the link for the article - Very worthwhile reading.

Jack Flesher's paragraphs on rendering intents are quite clear and helpful there.

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

Andy

:lurk

This thread is great. Kinda like Mac vs. PC (Mac, of course) and Canon vs. Nikon (Canon, of course). Lot's of great stuff being contributed here - thanks guys!

:lurk

DavidTO

Andy wrote:

:lurk

This thread is great. Kinda like Mac vs. PC (Mac, of course) and Canon vs. Nikon (Canon, of course). Lot's of great stuff being contributed here - thanks guys!

:lurk

Did someone say Mac?

pathfinder

I think I finally grok Rendering Intents, and they seemed really other worldly to me before.

I actually have an idea which one I might prefer to use and why images that folks have been so helpful to point out blown highlights, can actually print so nicely.:):

DavidTO

Andy:

I think I smell a tutorial!

chrisjlee

Andy wrote:

This thread is great. Kinda like Mac vs. PC (Mac, of course) and Canon vs. Nikon (Canon, of course). Lot's of great stuff being contributed here - thanks guys!

Didn't think that many people would respond to this thread. Very interesting nonetheless.

jfriend

A few more words on ProPhotoRGB

pathfinder wrote:

Pro Photo is very, large 16 bit gamut that "encompasses all the colors we can capture with the sensor, and the vast majority of the colors we can see" stated Bruce Fraser in Real World Camera RAW for PSCS2.

I read that book for PSCS a couple of years ago, and got my definition of Pro Photo slightly askew. Sorry, for any confusion about my statement.

Fraser goes on to say that "if you see serious color clipping on a conversion to Pro Photo RGB, you're capturing something other than visible light!"

The big advantage of ProPhotoRGB is that it can describe pretty much anything that your camera can capture (in some cases, it's even wider than what the camera sees).

So, while it preserves what you've captured, it can be dangerous to leave your image in ProPhotoRGB when you're taking it to any output device or even when you're editing it in Photoshop before taking it to an output device because you run a high risk of having colors in your image that simply don't fit within the capabilities of the output device. In that case, it's safer to control the conversion in Photoshop yourself rather than just letting some print driver decide what to do with out of gamut colors.

Keeping with the crayon analogy from before, because the range of ProPhotoRGB is so large, if you express it in only 8-bits of precision then each crayon in 8-bit ProPhotoRGB is so far from the neighboring crayons that you get posterization and lose color definition. If you express it in 16-bits, that problem goes away because there are so many more crayons.

pathfinder

Good point, jfriend - you definitely do need to open files from RAW conversion into Photoshop in 16 bit, if you want to introduce them in the ProPhoto Color space for exactly the reason you described.

LuckyBob

Another couple of fantastic links regarding color spaces:

http://www.drycreekphoto.com/tools/printer_gamuts/prebuilt.html
http://www.drycreekphoto.com/tools/printer_gamuts/gamutmodel.html

They have pre-rendered plots of mostly printers, but also a handful of cameras and all the major color spaces so you can visually compare them. It's usually pretty shocking to see how limited most printer/paper combos are in comparison to what the camera or color space is capable of representing (learn to love your ICC profiles . Also, if you want to directly compare a handful of setups at the same time, the second link above lets you plot several at once; for example, Adobe RGB, a Canon 10D, and Epson 2200 using Premium Luster (which is my normal setup).


Note: If you don't see the 3D model of the color space(es), you need to install a VRML viewer. This link (http://www.drycreekphoto.com/tools/printer_gamuts/) on their site has links to common VRML viewers. First post to boot :

cletus

LuckyBob wrote:

First post to boot :

Hello, LuckyBob

Welcome to dgrin!

hooyah

could i just ask a question here?

Okay i've profiled my monitor using eye one display 2 and basically i shoot everything in sRGB as well as do my processing in it. Photoshop wise and ACDsee pro i've managed to adjust my pictures to the exact colors i want.On ACDsee pro, everything is fine and dandy, i can see the exact colors because they're ICC-aware-note i am working in sRGB at all times.

But when it comes to displaying the pictures in say, windows picture viewer or on non icc aware internet browsers such as firefox and IE, which are supposed to recognize the sRGB profile only-there is a complete shift of colors even when i embed the sRGB profile or not in those pictures. why is this so?

Other misc info, i've got the monitor profile running under my ATI card under card mgt, windows supposedly is running the sRGB profile. My cs2 is set to sRGB. what really gives? anyway for me to remedy this?

flyingdutchie

hooyah wrote:

could i just ask a question here?

Okay i've profiled my monitor using eye one display 2 and basically i shoot everything in sRGB as well as do my processing in it. Photoshop wise and ACDsee pro i've managed to adjust my pictures to the exact colors i want.On ACDsee pro, everything is fine and dandy, i can see the exact colors because they're ICC-aware-note i am working in sRGB at all times.

But when it comes to displaying the pictures in say, windows picture viewer or on non icc aware internet browsers such as firefox and IE, which are supposed to recognize the sRGB profile only-there is a complete shift of colors even when i embed the sRGB profile or not in those pictures. why is this so?

Other misc info, i've got the monitor profile running under my ATI card under card mgt, windows supposedly is running the sRGB profile. My cs2 is set to sRGB. what really gives? anyway for me to remedy this?

What is your photoshop setup?
Make sure that your color-setup of your working-space is the standard sRGB. Don't assign your monitor profile to your working-space!

IE and other ICC-unaware applications simply ignore the embedded color-profile and assume it is sRGB. Therefore, embedding color-profiles in your pics for IE is useless.

Do not run your monitor profile under your ATI color management!
Eye-One created a monitor profile after it calibrated your screen. This profile should be assigned to your desktop's Color-Management settings (Display Properties --> Advanced --> Color Management). This profile is also used to update your LOT of your ATI card. This is done automatically by Eye-One software running in the background. Don't assign your newly created monitor-profile again under your ATI-specific color management settings. Leave the ATI specific color-settings alone.

I always shoot in sRGB mode. Most (almost all) browsers ignore the embedded profile and assume sRGB. Most online and 1-hour-wait print-services ignore the embedded profile and assume sRGB as well. If you have your own (inkjet) printer, then i suggest you shoot in adobeRGB. These printers usually are able to represent this colorspace.

colourbox

It's a little misleading to say one space has "more colors" than another, because the color coverage is 3-dimensional. And one space can be larger than another at full brightness, but smaller at another brightness level. There is often not an absolute "this is bigger than that" answer. When you overlay, for example, an Epson 2200 matte profile over Adobe RGB and sRGB, you find that while Adobe RGB does cover more of the Epson colors than sRGB, there are still a few Epson colors that neither covers. A purist would use ProPhoto to make sure a photograph actually uses the entire Epson ink gamut, if they thought their viewers would notice.

If you have a Mac and want to observe this yourself, start your ColorSync Utility, choose a profile, right-click to Hold for Comparison, and choose a second profile. By rotating the profiles in 3D, you can see where one profile does and does not cover the colors of another.

If you don't know what you're doing with color management, sRGB is fine, you can stick to that. Use of the other color spaces requires some knowledge of how to convert between spaces so you can get to sRGB safely for the Web.

If you are shooting Raw, you don't need to care what color space the camera is set to. The color space is not actually assigned until Raw is converted to JPEG or other non-Raw format. Raw is raw.

Finally, for the sake of accuracy. There are no sRGB or ProPhoto RGB sensors. There are no sRGB output devices. sRGB and ProPhoto are abstract, idealized constructions. If a camera or printer is sRGB, it's because it's been calibrated to produce that by the factory, camera settings, or user, but without the calibration, no way is a native sensor or inks going to produce anything that matches sRGB.

hooyah

flyingdutchie wrote:

What is your photoshop setup?
Make sure that your color-setup of your working-space is the standard sRGB. Don't assign your monitor profile to your working-space!

IE and other ICC-unaware applications simply ignore the embedded color-profile and assume it is sRGB. Therefore, embedding color-profiles in your pics for IE is useless.

Do not run your monitor profile under your ATI color management!
Eye-One created a monitor profile after it calibrated your screen. This profile should be assigned to your desktop's Color-Management settings (Display Properties --> Advanced --> Color Management). This profile is also used to update your LOT of your ATI card. This is done automatically by Eye-One software running in the background. Don't assign your newly created monitor-profile again under your ATI-specific color management settings. Leave the ATI specific color-settings alone.

I always shoot in sRGB mode. Most (almost all) browsers ignore the embedded profile and assume sRGB. Most online and 1-hour-wait print-services ignore the embedded profile and assume sRGB as well. If you have your own (inkjet) printer, then i suggest you shoot in adobeRGB. These printers usually are able to represent this colorspace.

My photoshop set up is under sRGB mode as well.Under the display settings, the ATI card is automatically updated with the profile created by i1 match, that i'm aware of.

The important question here to ask really is how come if the internet browsers display sRGB profiles by default-why would my pictures, whether it's embedded in sRGB or have no profile at all, display very differently from that when i view it in Photoshop or other color aware applications.It seems only that pictures embedded with monitor profiles created will match that of the pictures displayed on the web. Yes i know, i shouldn't save it under monitor profiles. But i'm really curious to know what's the cause as to why even when i DO save the pictures with sRGB profiles, the colors of the pictures actually turn out to be different and in fact match that of the monitor profile colors in internet browsers.

Here's a link documenting what people are facing as well

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00DRb6&tag=