M8 - sRGB vs Adobe RGB

[Rick]

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Reasoning was that I'd read about the Wider Colour Range using Adobe and that if Abode had developed Photoshop it seemed logical to use their profile.

 

Really would appreciate any comments.

______________________

Thanks and regards, Tom

Photography by Tom Lane

 

Adobe actually uses ProPhoto in their RAW converter for PS and LR. ProPhoto is the widest common color space available to you and it is native to Adobe LR and RAW. It is not a profile. It is a color space. It is the one Adobe uses for their RAW converter. Raw files brought into LR for development are mapped to the ProPhoto color space and they stay that way through the LR workflow unless you chose to convert them.

 

When you move them to PS, you are asked if you want to keep them in that color space or do you want to convert them to something else. To make it more complicated you may chose to work with them in something else, but you have PS set with something else as its default work space. It becomes a little bit of a task to get all of this straight and keep the workflow consistent.

 

Adobe RGB was developed a long time ago and was slighted by Microsoft back in the days when these two companies really went head to head in many areas. So, Microsoft came up with its own color space with very little data overhead, but the gamut is not as wide.

 

If you compare AdobeRGB and sRGB, they are both similar when compared to ProPhotoRGB which is much wider. The difference seems to be in the deeper color tones.

 

Even though we can not see these colors displayed on our monitors, hopefully, some of the new printer inks from Epson and HP (probably Canon too, I just don't know enough about Canon) are going to be able to print some of this gamut. Someday we hope that our monitors will be able to display wider gamut as well.

 

At the very least, when you use ProPhoto, you don't have to throw away data from the sensor that someday may be used to make a better print.

[sandymc]

But intellectually, I'm curious as to where Davis's understanding arose. He gave the feeling that this "don't embed the profile" was something just recently discovered. If anyone has insight on this, I would like to hear it.

 

The only reason I know of not to embed the profile is in web design environments, where you want the color of all element on the page to always match. E.g., when you have a color from a logo in both the border (as flash or CSS or whatever), and an image (e.g., jpeg). The issue there is that usually the HTML/Flash elements are not, and cannot be, color managed. In that case, not embedding a profile will (except for the Firefox with full color management enabled) ensure that all colors are the same. The color will be "wrong", but at least they will match. However, for normal photographic use, you usually want correct rendering of colors rather than matching to other page elements as the first priority.

 

Sandy

[lanetomlane]

Adobe actually uses ProPhoto in their RAW converter for PS and LR. ProPhoto is the widest common color space available to you and it is native to Adobe LR and RAW. It is not a profile. ........

 

Thanks for the information Rick. Yes, I understand that "profile" was the wrong word to have used, I did actually mean Colour Space.

As I do more reading on this subject I do find it to be fascinating and who knows, one day I might even get to understand it.

Having now read about ProPhotoRGB I can see the advantages and will certainly give it a try when I get chance. Seems wrong not to use all (I should say as much as possible) of the available information from the DNG file, although I do realise that ProPhotoRGB gamuts will be compressed (if that's the right word) when it goes to print, whereas on the other hand, I think my Epson printer has a slightly larger gamut capability than the file produced by AdobeRGB.

___________________

Regards, Tom

[ChrisC]

Now I am totally confused....

 

I've been away from my computer for a couple of days and I'm glad the thread has moved on, and that I wasn't the only one confused.So I'm really glad that Sandy has contributed :

 

The only reason I know of not to embed the profile is in web design environments.....

 

If it's good enough for Sandy - that's good enough for me. Thanks Sandy

 

Howard wrote :

 

... when one uploads a file to the web, it should in general be in sRGB without embedded profile.

 

Whether the file was shot in sRGB or Adobe RGB or any other color space, it should be uploaded as sRGB. Whether one does that via "Assign Profile..." or "Convert to Profile..."....... the important thing is that the file be in sRGB (again, generally speaking) when it is sent to the web.......

 

OK, I understand that Assigning or Converting, carries the colour information in it's correct language. But I realise now that the term Embedded signifies more than carrying the colour information in it's correct language. It clearly is a specific technical term, and I'm guilty of having used it flippantly and inaccurately.

 

Can someone please explain Embedded to me? and explain the significant difference between an Assigned or Converted file with an Embedded profile as opposed to that file without an Embedded profile. What is the real world difference?

 

.................. Chris

[sandymc]

Can someone please explain Embedded to me? and explain the significant difference between an Assigned or Converted file with an Embedded profile as opposed to that file without an Embedded profile. What is the real world difference?

 

Chris,

 

These are my definitions - you mileage may well vary(!). The primary distinction is between (a) what color space the image data is in, and ( the presence or not of a color profile in the file.

 

Embedded - a image file that contains e.g., an sRGB profile. The image file then literally contains the entire ICC profile as a section of the file. In JPEG file, the section is delimited by the "APP2 marker". The alternative is an image file that just contains data, but no profile.

 

Assigned - usually means that an ICC profile has been added (aka embedded into) a file without changing the image data. Unless the image data in that file was already in the color space of the profile, the result is not good.

 

Converting - usually means that the image data is converted to a color space, and the profile for that space is embedded into the file. This is what should occur. So, e.g., when you ask Lightroom to write an sRGB JPEG, it will convert, so it will both convert the image data from Lightroom's internal color space to sRGB, as well as embedding an sRGB profile in the JPEG file.

 

Sandy

[ChrisC]

Sandy - I'm grateful for your clear answer. My thinking wasn't too incomplete, and thankfully my world is still round [though one can't be too certain in the wacky world of colour management]. Many thanks.

 

............... Chris

[ho_co]

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Chris--

Just a quick addition to Sandy's post: In my understanding, the only time to "Assign" a profile is when one has a file without any profile but for some reason requires that it have one.

 

Example--you download from the web a file that doesn't contain a profile; but to work with it, you need to give it a profile. You then Assign a profile, which means about as much as, "I don't know what it is, so let's assume it's sRGB (or whatever)."

 

In other words, for practical purposes, one just doesn't use "Assign profile...."

 

 

 

Sandy--

Term clarification request: When you speak of "untagged" files, doesn't that simply mean files that don't contain color profile information?

 

That is, aren't "untagged" files those for which I didn't check the "Embed color profile" box in Photoshop?

[sandymc]

Term clarification request: When you speak of "untagged" files, doesn't that simply mean files that don't contain color profile information?

 

That is, aren't "untagged" files those for which I didn't check the "Embed color profile" box in Photoshop?

 

For practical purposes, that's correct. The only theoretical exception is that some files can simply be marked as having a color profile rather than having it embedded. So tagged covers "marked" as well as having an embedded profile. But I can't think of any practical photographic situation today where that's done.

 

Sandy

[Rick]

For practical purposes, that's correct. The only theoretical exception is that some files can simply be marked as having a color profile rather than having it embedded. So tagged covers "marked" as well as having an embedded profile. But I can't think of any practical photographic situation today where that's done.

 

Sandy

 

QED... "In other words, for practical purposes, one just doesn't use "Assign profile...."

[MikeMyers]

I'm also new to this, and the more I read, the more confused I get.

 

Could one of you please describe what the differences will be to a person viewing the file, based on which of these parameters may or may not be set? I guess this needs to be asked for three possible situations:

a) a photo directly viewed on a computer, using a normal computer screen

a photo viewed on the internet using any of the browsers available now

c) a photo printed by a typical ink-jet printer at home

 

Will the colors look different? If so, in what way? Please describe what a person would actually see, rather than what's going on technically.

 

(Is there any difference in what people will see in jpg images vs. dng images?)

 

Thanks in advance for any help here...

[ChrisC]

QED... "In other words, for practical purposes, one just doesn't use "Assign profile...."

 

And :

 

 

... the only time to "Assign" a profile is when one has a file without any profile but for some reason requires that it have one.

 

Example--you download from the web a file that doesn't contain a profile; but to work with it, you need to give it a profile. You then Assign a profile, which means about as much as, "I don't know what it is, so let's assume it's sRGB (or whatever)."

 

In other words, for practical purposes, one just doesn't use "Assign profile...."

 

Howard - Thank you, and yes I understand the use of Assign Profile in your example [in practice probably not a common need these days]. But I'm actually one of those people who uses 'Assigned Profiles' on just about every image as a regular part of post production.

 

Courtesy of Joseph Holmes, I have many of his Colour Spaces installed, and start my images in one of his Work Spaces. Each Colour Space renders the image colour differently on screen [with the cautionary caveat that these spaces are larger than Adobe98 and hard proofing is desired] and the colours are mapped differently than Saturating/De-saturating would achieve.

 

Assigning is actually extremely practical as it does not change the file in any way; it merely interprets colour in the style of the Colour Space of the Assignation, and one can go back and forth trying various Assigned Colour Spaces without doing any file damage. Converting, as I simplistically understand it has rather a bruising effect on the colour information with it's Rendering. When I work B&W, I Assign JH-99 [a Colour Space effectively without colour] and that leaves me free to 'play' the image using all of the colour editing controls [like Selective Colour] whilst viewing the image as B&W on screen. The original colour information is still safe, my interpretation is B&W, when finished a Save As file can be made in a B&W [non]-Colour Space. In threads on B&W Converters I have offered this as a better alternative to Converting to B&W prior to Post Production as it gives a greater array of Post Production tools, and does not prematurely throw all that useful colour information away. I've learnt that people do seem keen to quickly throw information away in their rush to B&W.

 

Assign Profile is an extremely valuable tool for me.

 

................. Chris

[sandymc]

Assigning is actually extremely practical as it does not change the file in any way; it merely interprets colour in the style of the Colour Space of the Assignation, and one can go back and forth trying various Assigned Colour Spaces without doing any file damage.

 

Yes, and if that workflow gives you what you want, then great. However, the downside of that workflow is that your color rendering depends on an interaction between the space that you assign and the space that you output to. A more conventional workflow tries to give the same color regardless of output device/space, to the extent that's possible within the constraints of gamuts.

 

Sandy

[MikeMyers]

Rich, thanks for taking the mystery out of all this. Lots of websites and charts and graphs have confused me as much as they've educated me, but you're the first person to put it all into simple, easy-to-understand terms.

 

I mostly produce images for the internet, meaning they will at some point get converted into the jpg format. So, I need to end up with sRGB. Thanks to your explanation, I was able to understand a website dealing with Lightroom and how it deals with color space.

 

I use Lightroom, and have found it's quite easy to shoot in 'DNG' format, and then to eventually export my finished images to 'JPG'. Since Lightroom is mostly being used with my DNG negatives (raw format) I thought that I didn't need to bother with color space until I export them. However, this page (Lightroom Color Spaces - O'Reilly Digital Media Blog) tells me that after doing all that work in Lightroom, when I export to sRGB I'm going to lose quality in my images because of clipping. Is there any way to edit in Lightroom, and get it to work for sRGB???

 

You've also got me thinking I've got a major problem. It is important to calibrate the monitor, but I'm usually using a Toshiba or Sony laptop. As far as I know, there's no way to calibrate the screen on a laptop - if it can be done, I don't know how to find the controls. So, if I do all my Lightroom work on the laptop, and it's not calibrated correctly, who knows what my images might look like on other people's displays. I found a discussion page in a forum that I almost understood (thanks to your posting), but the more I read, the more impossible it seems to get. Here's the page: (http://photo.net/digital-darkroom-forum/008FNY).

 

Are there any ways to get Lightroom to work in sRGB, so what I see on my laptop will represent what people will eventually see when I post the jpg image on the web?

[MikeMyers]

Do you have any recommendations for a Laptop?

 

I read this paragraph:

 

"The two biggest problems resulting in wrong colours when producing a photograph destined for online viewing are: (a) having a profile embedded that is not sRGB - as I mentioned before, most programs ignore profiles and will thus display incorrect colours (no embedded profile is fine - sRGB is then assumed); ( editing the photo on a monitor that's not calibrated (or at least badly adjusted, deviating from the manufacturer's defaults) - when seen on other computer screens, the second problem can result in poor colours and/or an image that's too bright or dark."

 

I can make sure my images are sRGB, but I don't think my Toshiba laptop has any controls for calibrating the screen. This issue caused me a lot of problems many years ago when I used a different laptop - pictures looked great on the laptop, but were way too dark for anyone else looking at them. This probably applies to many of us who post images while away from home, and all we've got to work with is a laptop.

 

(I assume that if the histogram looks right, I can't be too far off......)

 

 

 

 

.....added later......

This page (http://photo.net/digital-darkroom-forum/008FNY) implies that it might be impossible for me to make any changes to my laptop. Doing a search for Toshiba screen calibration didn't find anything useful either.

[MikeMyers]

Aha! Gee, there's so much I just don't know.

 

I always assumed that a screen calibrator would require me to adjust things on the display until they "looked right". I never imagined that there would be software involved, that would use a hardware device to monitor the display and then change the internal video display software to make these adjustments.

 

After reading your post, I did a search and ended up at Spyder3Pro - Datacolor - Global Leader in Color Management Solutions. Watching the video was VERY informative.

 

I guess that this problem is solved - if I get one of these devices, I can calibrate all my displays, and stop thinking whether or not they're showing me what my images really look like.

 

 

 

I need to send the manufacturer an email, and ask how their unit handles multiple displays. My home computer has two displays (from different manufacturers), and hopefully there's a way to adjust them both independently. That's a minor consideration though, compared to getting my laptop right.

 

Thanks!!!