Colour rendition on screen

[marlunn]

This will probably kick of a conversation that will go way over my head but - I put an image up into a competition in Photocrowd, a red rose, however it 'changed' when viewed in the competition and the reds became darker and 'muddy' (not sure this will work here so please bear with me ), the first image is the one I put up and on my screen the reds are clear and shades of 'red'



this is how it looked when I uploaded it to the competion



now - looking at the original on my screen it looked fine - looking at the same image on my screen in Photocrowd looked dark and muddy - scatches head - reviewed image as tiff file in PS - looks good - save as a .jpg - looks same as first image - scratches head - walk through process again, open tiff with use embedded profile selected, and noticed a tick box when I went to 'save as' as a jpg bottom right of the window - icc profile - pro photo rgb not noticed that before

untick this and lo we have a saved jpg that is darker and muddier on my local machine

so - why did it look okay on my local machine saved with that - but not okay with the same setting on Photocrowd, I guess that it uses a local machine icc profile but why only this image and no others i have saved and uploaded the same way, a few more checks later and I see a difference, its cos i used adobe rgb on the others not Pro Photo! Guess i must have played a bit at some point and forgotten the change

Moral of the story - pay attention to details and colour space - it has an impact !

Lesson learnt - colour management on local system that is okay may be a problem on remote systems so use the colour space for the environment its going to be used in!

[Dave Humphries]

I have no practical experience here Mark, but from memory of past discussions, you need to first convert the image to an sRGB colourspace, I believe this will retain more colours than simply displaying as sRGB - which is what I think unticking the box might have done.

If it is important to you to retain a ProPhoto version, be sure not to save over your master tiff after conversion.

Whether the image displays with the proper colorspace also may depend upon the software used; some web browsers, applications and/or operating systems are 'unreliable'; hence why sRGB rules for on line display.

Personally; I work sRGB throughout (camera, editing, etc.) to avoid these very issues since I mostly display on line and rarely print - but that's not for everyone.

[Simon Garrett]

Wot Dave says. In Photoshop, go to Edit -> Convert to profile (not Assign profile) and choose destination profile sRGB... and then File -> save as...

Is your monitor calibrated and profiled? I mean with a hardware calibration tool (colormunki, i1 display, spyder etc). If not, then always use sRGB for every purpose, or you are likely (read: almost certain) to get colour mismatches at some point. You also must calibrate/profile your monitor if it's wide-gamut, or again colour mismatches are virtually certain.

[dje]

Hi Mark

The first image has an embedded icc profile (ProPhoto RGB) but the second image has no embedded profile. My guess is that the profile is getting stripped in PhotoCrowd. In the absence of an embedded profile, I believe most browsers (including those that are colour managed) will simply assume sRGB which will of course give in-accurate colours if a different colour space is used in the image.

You can use software like PhotoMe or EXIFTool Gui to look for embedded profiles.

As Dave says, it is safest to make your web images sRGB.

Dave

[marlunn]

Dave, i do my own printing so use adobe space (normally) for any final image - yep the original tiff pro-photo is saved and seperate for any future development of monitors / printers into that area (a vain thought that they may be worth the effort ) any amendments post that are saved seperately eg .jpg in aRGB and yep converted on opening in PS

Simon, monitor hardware colour calibrated - and printer icc profiled for printer / ink and on each paper used, very aware of colour matching

Dave, yep - thanks


This was a case of me 'forgetting' I must have played around and changed LR (hmm thought - it did a upgrade recently, nah they would not do that would they) to pro photo and not taking into account the potentail limited colour space of the internet and possibly the impact of their system on it.

To be clear the image was processed in LR exported to PS edited and saved as a tiff in pro-photo space - opened in LR to finish and print - soft proofed and the output print matched the screen - as near as any do given print reflection of light vs monitor projection of light, all in pro photo space.

When re-opened and saved to .jpg it looked fine on the monitor and matched the tiff image, on my monitor. My error not to convert to aRGB at least or preferably sRGB to output for internet. I have not done that before for facebook etc so assumption is my 'play' in LR to pro photo is the culprit and a lesson learnt to be very aware of colour space to use / environment when creating images!!

[Simon Garrett]

Lightroom always processes internally in ProPhoto RGB*, but you can choose the colour space when you export or edit in an external application (e.g. PS). For external editing the defaults are set in Edit menu -> Preferences -> External Editing tab.

As you say, it will look fine on your (colour-managed) monitor in any colour space, but sRGB is nearly always safest for the web, IMHO.

(*Strictly, Lightroom uses several colour spaces internally, but there's no choice. In Develop Module it processes in ProPhoto RGB with linear Tone Response Curve, it shows histograms and RGB values in ProPhoto with sRGB's TRC - the so called "Melissa RGB", it uses Adobe RGB for previews in Library module and sRGB in web module.)

[Manfred M]

Mark - what others have written is correct, but let me put a slightly different spin on it.

Your digital camera can capture the full visible spectrum of light. Technically, it can capture more and that's why the camera manufacturers include two filters; one is used to cut off anything that falls into the near infra-red and the other anything that falls into the UV. Much of the view of what we humans can see is based on some work that was published back in 1931 by the International Commission on Illumination (CIE). While there are more modern updates (1976 CIE LAB, for instance) to this, this is often used as the baseline when discussing colour vision / reproduction.

Colour computer screens have been around a lot longer than digital cameras, so colour capabilites were more or less based on other drivers. Back in 1996 Microsoft and HP got together and came up with a standard for based on what colour displays were capable of displaying, so we got sRGB with its 16.8 million distinct colours. It became the baseline and even today, the vast majority of computer screens are sRGB compliant. This is great, except for one thing. THis colour space only deals with around 30% of the colours our camera can capture and our eyes can see.

In 1992, Adobe comes along with AdobeRGB. They had different business niche and needed a solution there. Much of the work that was produced by Adobe software was destined for the print industry; books, magazines, catalogues, primarily done on offset presses. In printing everything is done with CMYK inks, so Adobe's colour space effectively aligned the RGB in our computer screens with what printers were capable of doing. This resulted in a colour space that covers about half the colours that we can see. Wide gamut colour displays are capable of displaying virtually the whole AdobeRGB colour space.

In 2012, Kodak published the ProPhoto colour space, that covers around 90% of the CIE LAB colour space (and probably 100% of "real world" colours). People criticize one aspect of this colour space; it includes colours that are outside of the the CIE LAB colour space (i.e. they can't be seen). When Lightroom first came out, this was the colour space it used internally for processing and no options for other colour space use existed. Later versions let the user change the default to sRGB or AdobeRGB. Another criticism of this colour space is that it can't be natively shown on any device; there are no ProPhoto compliant displays and even top end colour photo printers (which exceed the AdobeRGB capabilities), use a limited part of the ProPhoto colour space.

AS A GENERALIZATION, WORKING IN 16-BIT PROPHOTO IS CONSIDERED A 'BEST PRACTICE' WHEN WORKING WITH RAW DATA. Not everyone agrees, so I won't get into those arguments right now. The only real risk is that the remapping to another colour space may give you results you may not like. Not all editors support ProPhoto.

One problem with all of these colour spaces is that they use the same R,G and B numeric values to represent different colour shades. Image files (usually) have this colour space data embedded in them, and colour managed software will adjust how it interprets this data and will display / print it properly. A lot of software is not colour managed and the assumption is that all colour data is sRGB. Wide gamut image (AdobeRGB and ProPhoto) images displayed as sRGB will look quite dull. Editing in ProPhoto an exporting as sRGB will solve your issue.

Lots more interesting stuff that I won't go into right now (rendering intents, etc.)...

[dje]

An interesting aside - when I viewed and commented on this thread last night, I was using my desktop and could see a distinct difference in the the red colour of the two images. When viewing them on my iPad this morning, they look exactly the same, both having the same muddy red colour that Mark mentioned. There is obviously no colour management going on with my iPad (either with Safari or Chrome). This re-inforces the benefit of using srgb with web images.

Dave

[marlunn]

just played with another image and saved as pro photo as a tiff, then saved as a .jpg with that profile, then to put it up onto web I re-opened the original tiff, converted to sRGB and saved as a .jpg then put them both up onto Facebook and they both look the same - ho hum

but in future any that will see the back end of another server will get set to sRGB for safety sake.

[Manfred M]

An interesting aside - when I viewed and commented on this thread last night, I was using my desktop and could see a distinct difference in the the red colour of the two images. When viewing them on my iPad this morning, they look exactly the same, both having the same muddy red colour that Mark mentioned. There is obviously no colour management going on with my iPad (either with Safari or Chrome). This re-inforces the benefit of using srgb with web images.

Dave

Dave - my understanding is that while there is some colour management in all of the web browsers, the only one that is fully colour managed is FireFox. I see this issue when running FireFox on both my Windows 8.1 laptop, Windows 7 desktop and on my iPad.

[dje]

Dave - my understanding is that while there is some colour management in all of the web browsers, the only one that is fully colour managed is FireFox. I see this issue when running FireFox on both my Windows 8.1 laptop, Windows 7 desktop and on my iPad.

Manfred I haven't tried iOS Firefox, must give it a go. I'm a bit of a fan of Mozilla, use their email software Thunderbird all the time!