Can RAW files be converted to different colour spaces?

[wideangle]

If I initially shoot RAW images in camera but have the camera set to sRGB, am I able to change this in my RAW converter to say Adobe RGB if I want?

[Jules]

Good question and I'll be interested to see the answer.

I think Adobe RGB is a larger colour space that sRGB, so maybe you can go from Adobe RGB to sRGB, but not the other way?

[ricktas]

Yes. but remember that if you convert from a smaller colour space to a larger one, then the missing colours are not just created magically to fit. So you can say go from Pro Photo to AdobeRGB to sRGB and each time you convert to the smaller colourspace you will lose some colours. But go sRGB to AdobeRGB to ProPhoto you dont magically acquire extra colours that did not exist in the first place.

[Calxoddity]

Hi,
I thought raw images didn't have a colourspace?

Regards,
Calx

[Jules]

Yes. but remember that if you convert from a smaller colour space to a larger one, then the missing colours are not just created magically to fit. So you can say go from Pro Photo to AdobeRGB to sRGB and each time you convert to the smaller colourspace you will lose some colours. But go sRGB to AdobeRGB to ProPhoto you dont magically acquire extra colours that did not exist in the first place.

So would you be likely to see banding as a result of converting from a larger to a smaller colour space?

[ricktas]

Not really Jules, what happens is the software finds the closest colour to the one in your photo and uses that, so it just cuts down the range of colours slightly each time.

[ricktas]

Hi,
I thought raw images didn't have a colourspace?

Regards,
Calx

They don't as such, but you have to give them one as soon as you work with it. Even displaying it on your screen. We are only now starting to see screens that can get close to displaying all of the AdobeRGB colourspace. But give it 5 years and we might be look at screens that can show ProPhoto space.

[wideangle]

So if I open a RAW image and then in the options click on the Adobe RGB colourspace (even though I have it set to sRGB in camera) that I can choose what colourspace I want it in before saving as a TIFF/JPG?

[Calxoddity]

Hi again,
Just to follow up my question further up, raw photos don't have a colourspace until you convert them to another format using a particular colourspace.

The in-camera setting is applied to the in-camera jpeg conversions, and does not affect the raw.

Once you have applied a colourspace to a resulting jpeg or tiff, making something small fit into a larger colourspace would appear to result in no gain (ie if you went ARGB > SRGB > ARGB through 3 generations of a saved tiff, the first ARGB image and the final one may have different colour if the shot was actually using colours in the full ARGB gamut originally).

I hope that makes sense!

Regards,
Calx

[ricktas]

So if I open a RAW image and then in the options click on the Adobe RGB colourspace (even though I have it set to sRGB in camera) that I can choose what colourspace I want it in before saving as a TIFF/JPG?

Yes, but as sRGB is a smaller colourspace when it goes to adobeRGB it will not be making full use of the gamut available in adobeRGB cause the data above what sRGB contained didn't exist to start with.

[ricktas]

Hi again,
Just to follow up my question further up, raw photos don't have a colourspace until you convert them to another format using a particular colourspace.

The in-camera setting is applied to the in-camera jpeg conversions, and does not affect the raw.

Once you have applied a colourspace to a resulting jpeg or tiff, making something small fit into a larger colourspace would appear to result in no gain (ie if you went ARGB > SRGB > ARGB through 3 generations of a saved tiff, the first ARGB image and the final one may have different colour if the shot was actually using colours in the full ARGB gamut originally).

I hope that makes sense!

Regards,
Calx

Exactly, BUT most monitors display using sRGB, so even though your photo in RAW doesn't have a colourspace, what you see on your screen is being limited to sRGB, even in your RAW converter. Gets confusing eh?

[wideangle]

Yes, but as sRGB is a smaller colourspace when it goes to adobeRGB it will not be making full use of the gamut available in adobeRGB cause the data above what sRGB contained didn't exist to start with.

Thanks everyone, ironically though most lab printers do not accept Adobe RGB colourspace, well none that I have dealt with yet. I suppose if you are doing a lot of your own printing then it may be a different story?

[ricktas]

Thanks everyone, ironically though most lab printers do not accept Adobe RGB colourspace, well none that I have dealt with yet. I suppose if you are doing a lot of your own printing then it may be a different story?

Ah, but most home printers cannot print the adobeRGB gamut either. In fact most cannot get the full sRGB gamut..can't wait for the future.:D

[clm738]

Isn't it better to set your camera to Adobe RGB and develop in RAW then convert to sRGB for printing or web use?

[ricktas]

You can develop in RAW whether it is set to AdobeRGB or sRGB, but yes it is better to save in sRGB for printing at web at this time.

However, firefox and a few other browsers are colourspace aware so if you view an AdobeRGB photo over the net using a colourspace aware browser, it doesn't really matter. But an AdobeRGB photo in a non colourspace aware browser (that just assumes photos are sRGB) will look flat and slightly less saturated.

[arthurking83]

I have to disagree with Rick on the raw colourspace issue.

A raw image is not colour aware. It's a collection of data that has yet to be converted into anything meaningful. There is a jpg image embedded in the raw data, that will be affected by the colour space you've selected in camera, but the raw data itself is not determined, even as you process the file on your PC(depending on what software you're using)

So if you choose a smaller color space(such as sRGB) in camera, the only file that is affected is the embedded jpg thumbnail, as the colour space is now set in that file, and any adjustment may look affected, but only in the jpg file. Any conversion of the raw image, to whatever format you later decide on in your editor is then determined by what you set the raw image too.
But that, once again, is only limited to the converted image, and not the raw image... if you have kept the raw image, you can subsequently convert it to any other colour space and you lose nothing.

The raw file is the key.. any converted raster image is set at the time of conversion, and shouldn't be changed to any other colour space, if colour accuracy is required. You'd set a raster image(eg. jpg/tiff) to a different colour space via the original raw file again.

Older Nikons all used to have various colour space settings that the user could select from, but in their later cameras(at least from the D300 and onwards, that I know of) they changed those variables to only two... from about 4 or 5. Now you only get the option of aRGB or sRGB.. for those users that are affected by colour space requirements, such as someone that shoots in jpg or tiff mode) the two options are enough.
Those that need ProPhoto colour space will almost certainly be shooting raw anyhow(but I don't know if that's an option in the Dx series cameras, definitely not an option in the Dxxx cameras).

This info is based on using the manufacturer supplied raw conversion software, as I have no idea on how third party software handles any colour space conversion, and this info has been supplied by a high quality photo printing lab here in Melb, and via some 'professional advice' on other forums.
(so technically it's limited to Nikon raw images, but I suspect that other manufacturers use the same principles too).

I used to shoot mainly in aRGB with my D70s, as I thought that was the better colour space to use if I ever wanted to print professionally(via this pro photo lab), and they explained this to me, I still started off shooting in aRGB on the D300, but then changed as the file naming gets all screwy and confuses me when I upload to the PC.

I just have to remember, that if I ever get any of my images printed at a pro lab, I need to batch convert the raw images to aRGB, as that's what they recommend, and then convert to the highest quality tiff format.

As a test, it's quite easy to try.
You can extract the embedded jpg image from the raw file(see RAW Extractor in this link (http://www.idimager.com/?page=freeware).
Once you set the camera to a specific colour space, the jpg image is then set.
If you then subsequently change the colour space of the embedded jpg to something different(usually sRGB to aRGB makes the biggest difference), the embedded jpg looks yuk! Try it and save it as a copy.

You can then change the colour space of the raw image, many times over, and save it as and alternate file with a different colour space save it as a jpg file and then use a non colour space aware program to see how the embedded jpg can be affected by colour, where the jpg image form the raw image will not be, and will always look the same as the raw image(depending on quality settings of course).

[Calxoddity]

What Arthur said! Well done sir. :th3:

BTW, here's a link that clarifies some of the concepts around raw conversion: http://www.bythom.com/qadraw.htm

[ricktas]

Im a bit confused here, seems some think I have stated a RAW file has a colourspace, which I haven't ?!?!

[Miaow]

i think whatever you save raw as after as a jpg in a program as is going to make it have a colourspace - ie save it as srgb and will be etc hmm though if camera is set on a specific colour space i think that would more apply to a jpg :confused:

[monkey]

so how do you find out which monitors support aRGB and ProPhoto?

Currently I have a Samsung SyncMaster BWX and cannot find out via the online specs.

Do FULL HD monitors support all formats?

[Miaow]

so how do you find out which monitors support aRGB and ProPhoto?

Currently I have a Samsung SyncMaster BWX and cannot find out via the online specs.

Do FULL HD monitors support all formats?

do you mean argb as in adobergb? Why would you want to work in abodeRGB when most browsers support sRGB more?

[Calxoddity]

so how do you find out which monitors support aRGB and ProPhoto?

Currently I have a Samsung SyncMaster BWX and cannot find out via the online specs.

Do FULL HD monitors support all formats?

Hooboy! We're getting into a whole other discussion here. The short answer to your question is "almost definitely not, but don't worry as most monitors don't."

I'm not sure I understand your qeustion re HD. "Full HD" is generally regarded as being 1080P resolution - it doesn't refer to colour gamut coverage (ARGB and SRGB are not formats). I guess the short answer here is "no".

Here's a link that provides a lot of info on monitors: http://www.tftcentral.co.uk/

PS - Just re-reading my response and it seems a little terse, but it's not because I'm being mean - it's because once you start trying to explain the ins and outs on this topic you never stop! Panel types, viewing angles, calibration or not, default gamut (usually exceeding SRGB) can all have a bearing on how you see the colours, and that's before we consider factors like the constraints of your target output and how accurate your colour vision is....

Regards,
Calx

[arthurking83]

apologies Rick, didn't mean to imply that you said that raw images are colour space aware.

but my point was only that, RAW images never lose any colour values as they are not colour space aware, regardless of what colour space you've set the camera too.

Where there may be any issues in viewing a raw file, set to one colour space, and subsequently converted to another colour space, would only be in the embedded image!

(I think??) there may be some image viewers or editors capable of handling raw files, that may display the embedded jog file as the thumbnail. FSViewer may be one of them(but I'm not sure??) as what's happened to me using that program has been weird.
If I open an NEF file in FSViewer, it displays the NEF as any of the Nikon software does, which implies that it's reading the embedded Nikon camera data(such as Picture Control settings) correctly, OR that it displays the embedded jpog file so that it performs quickly, which it does. Faster than any other raw viewer that I've used so far, in displaying hundreds of NEF images at once. Could just be optimal programming? I've also tried using Bibble Pro5, which is reputed to be the fastest raw image editor available.

What FSViwer does tho, is that it displays the NEF perfectly, but if I convert the NEF to a raster image, the resultant image looks less than woeful(and that's sugar coating the description by a long way too!.. nothing short of the worst raw to jpg/tiff conversion I've ever seen!).
**This is Nikon specific, and in my circumstances tho!!**

So what could happen(to any type of raw file):
if your raw image editor/converter is displaying a certain looking image(which looks good), which you then convert to a different colour space, if that program uses the embedded jpg for display purposes, and it's converting the embedded jpg as well as the raw data, then the display of that embedded jpg is obviously going to look affected in some way.

I highly doubt that any software would meddle with the embedded jog image in the raw file, but who knows what they do?.. and I'm not a programmer to be able to fully understand what happens to the raw file.
Other alternatives could be that, if the camera is set to aRGB, and then converted to sRGB using one program(eg in my case CaptureNX) and then I subsequently open that raw image in FSViewer..

1. I'm not sure if there's going to be any embedded exif data in the embedded jpg image(why would there be, it should be optimized for display in the camera), so being a jpg, the default colour space(for any viewer to display the jpg) would be sRGB.
2. there is exif data in the raw image then the software would assume that the embedded jopg would be the same(eg. aRGB).
3. if the software assumes that the embedded jpg is aRGB after colour conversion to another type, by another program, then it may display the jpg in the wrong format.

I'm curious by it all, but as I've never had any issues converting colour spaces using Nikons software, which is the only software I use to convert NEF's to raster images, I've never seen any colour anomalies.

crikey! I hope that made sense.. now I'm confused :D

[monkey]

@calx. thank i know little at the moment about monitors so wasnt sure bout my Full HD question either. is it best to work with a monitor then that supports Adobe RGB so you can get a true indiciation of what is going to be printed? If you dont have a Adobe RGB monitor then should you not save images that you want printed as Adobe RGB?

@Miaow the reason to work in Adobe RGS is to get better looking prints.

[ricktas]

If you want a monitor that can display the full AdobeRGB gamut, you are looking at several $thousand to get one. Some are now reporting about 97% AdobeRGB gamut and coming down in price, so its only a matter of time before technology allows us a full gamut at a reasonable price.

[monkey]

thanks ricktas. do you use a AdobeRGB monitor? Do most people at the moment use sRGB monitors and still saves prints in adobe RGB?

is 100% full gamut?

[ricktas]

100% is full gamut and I wish I did have an adobeRGB monitor. I think another important factor is monitor calibration with a Colorvision Spyder, Munkey, Eye-one, etc.

97% adobe gamut monitors are expensive: http://www.imagescience.com.au/products/Eizo-ColorEdge-CG241W.html
100% ones are even more so : http://www.imagescience.com.au/products/Eizo-ColorEdge-CG221-.html

[monkey]

wow you are not wrong!!!

Do you know what gamut the latest LCD/LED TV are usually at? The reason i ask is that im thinking of buying a new TV and teh samsungs come with a free 26 inch screen i could use purely for my office.

Also so given that you have an sRGB monitor do you get prints done in Adobe RGB or sRGB

[ricktas]

wow you are not wrong!!!

Do you know what gamut the latest LCD/LED TV are usually at? The reason i ask is that im thinking of buying a new TV and teh samsungs come with a free 26 inch screen i could use purely for my office.

Also so given that you have an sRGB monitor do you get prints done in Adobe RGB or sRGB

you would have to get the model details from samsung and contact them re gamut etc of that monitor, but as it is free, it is probably cheap too (see post above re price of adobe monitors). Prints should be done in sRGB unless your printer can handle adobeRGB (ask them).

[monkey]

yep i saw the prices thanks. hence my 'you aren not wrong' to the expensive advice from you
.
Yes my printer can support Adobe RGB however since i cant see sRGB? Given i cant see Adobe RGB on my monitor what should i do.

[ricktas]

take your photos in RAW and keep them. At present, convert to sRGB for printing and web display, but in future as prices drop etc, you still have the RAW file to use again and benefit from the available bigger colourspace at that time.

[Calxoddity]

Monkey,
Another thing to consider in all this - your printer's gamut will in all likelihood be less than the monitor unless you've spent bazillions on the printer, so the prints won't occupy the ARGB colourspace in any case and trying to squeeze ARGB into the available colourspace at printing can cause colour ickiness (sorry - technical term :o ).

Your hard earned cash would be better spent in ensuring the existing monitor is calibrated and the printed output looks like the pikkie on the screen (and use SRGB colourspace as your generic colourspace).

Regards,
Calx

[monkey]

hey calx thanks for that. I get them printed at a printing centre that supports aRGb if i want it too. But i hear what your saying, i might for now spend some cash to calibrate the monitor and concentrate on sRGb until things get cheaper.

what do pros do if they dont have a sRGB monitor?

[jev]

That's a thinking-error. Just because the final output device is not able to completely cover the larger color space of AdobeRGB doesn't mean it doesn't benefit from the larger color space of AdobeRGB (as compared to sRGB). A printer might be able to show much more yellow than a monitor can or that fits in either sRGB or AdobeRGB. That you can't see it on your monitor doesn't mean you won't benefit from it. Check out the excellent interactive color gamuth models from DrycreekPhoto (http://www.drycreekphoto.com/tools/printer_gamuts/gamutmodel.html) to get a feeling for it. Take for example AdobeRGB as reference model, sRGB as wireframe model and select an Epson 2200 on professional glossy paper for your solid model. Than look at the yellow and green - the printer can print much more yellow and green than fits either sRGB or AdobeRGB. Here's a screendump from that:
42426
The red wireframe is sRGB, the white wireframe AdobeRGB and the solid is what Epson can print. It certainly pays to use AdobeRGB (or even Profoto!) if you are going to a subtractive color based device from a additive color system.

Something similar is true for monitors (though obviously not the difference between additive and subtractive color systems). Look for example at the Eizo CG-220 LCD: that almost fits AdobeRGB but it is able to generate a bit more orange to purple than AdobeRGB can respresent.

[Calxoddity]

Thinking error? Does not compute! ;) A simplification maybe... Once you start getting printer and screen gamuts that are too widely divergent, it's harder to predict the appearance of the printed output. The printer may (for example) be able to do brighter yellows, but if that's not the result you're after, it's a wasted sheet.

If you have a Mac you can use the Colorsync utility to compare gamuts like in Jev's pikkie. I use it to compare different papers' output gamuts on my R1900 in relation to my screen sometimes.

Next time you're in an Apple Store, check it out (Applications/Utilities/Colorsync, click on a profile then right click on the resulting gamut graph and select "hold for comparison", then click on the other profile from the list that you want to compare it to. Instant overlay!).

Regards,
Calx

[wideangle]

OK, thanks for all the responses! This area of photography is certainly deep and at times confusing!!

[wideangle]

As a follow-up I have found some interesting and clear reading about sRGB/Tagged and untagged images etc.
http://www.vaps.org.au/Documents/sRGB,%20Tagged,%20Untagged.pdf

[cinvala]

Slightly off topic, maybe.
When I transfer images from my camera to my computer using lightroom 2. and save them as a .dng file, is there a colour space attached to the file at that point?

[wideangle]

Slightly off topic, maybe.
When I transfer images from my camera to my computer using lightroom 2. and save them as a .dng file, is there a colour space attached to the file at that point?

There should be, check your colour settings within lightroom to see what it is using, or alternatively right click a jpg thumbnail and see what colour profile is embedded - not sure why but colour profiles cannot be seen when right clicking a TIFF image for EXIF data.

[jev]

There should be
No, there should not be a color profile in there. DNG just is Adobe's idea of RAW...

[cinvala]

I've done a little bit of checking, .dng files don't attach a colour space to the file, but a colour space is used when displaying the file. Which I think means that the program that is being used to display the file, eg lightroom will attach it's default colour space.

[deloceano]

Thanks everyone, this is a really helpful discussion.

I have seen people mention ProPhoto colourspace - if I shoot in RAW and then develop using lightroom, can I choose this colourspace, or is it a plug in that needs to be sourced from elsewher - or does it only refer to the monitor colours?

Still a little confused about colour spaces - but its good to know that RAW images are unaffected by the colourspace selection in-camera - I was concerned that my 7D only had 2 selections, but if shooting in RAW it appears that doesn't matter.

Cheers

[junqbox]

Using ProPhoto is fine, as long as you have no intention of printing it until someone puts an approapriate printer on the market. You will be very disappointed with the results, severe flattening of colours, particularly in the yellow/red area of the gamut. Some pro labs can print from ARGB files (VisionImageLab in Sydney), I would imagine there would be one near you or you could do it over the interweb.