Blurb color management for JPG/TIFF

I'd like to know how does LR work with bitmap images such as JPG or TIFF.
On the website (which I found somewhat confusing, by the way) is described I can upload both sRGB/Blurb ICC images for RGB, or a specific CMYK space for CMYK mode.
I'd like to print a book with images collected from other photographer, so RAW exporting is not the way. Which color space should I tell them to export in? sRGB/Adobe RGB in 8bit and let Lightroom do the rest?
Regards,
Paolo

I have quite a knowledge in the field, so... is it possibile to know the exact profile it uses?
Is it the one you can download from the Blurb website?
Otherwise, which one is the closest? Is AdobeRGB an overkill for their gamut?
Thanks Eric

Similar Messages

Color management for flash player with hardware acceleration

I have tested the color management for flash player 10.2 with and without hardware acceleration (GPU) on different PCs with different video cards.
Videos that are played via flash without hardware acceleration on PC have proper color as designed in After Effects.
When I switch on hardware acceleration, the color shifts, for example green becomes lighter, although grey values are OK. I have tried this by writing a small Flash programme for playing a movie; I wrote two programmes one with color management as described in the article "Color correction in Flash Player" http://www.adobe.com/devnet/flash/quickstart/color_correction_as3.html and another one without color management. In both cases I got the same color shift when hardware acceleration was turned on. From the result I concluded that color management does not work when hardware acceleration is on.
My question is: are there any plans to have color management for flash player with hardware acceleration (GPU) in the near future?
We need to play complex high definition movies streaming through a high speed local area network that need hardware acceleration to avoid stuttering.
V. S.

Hi, LOL at my screen moniker. That's interesting that the FF beta has an Option for that. The only problem, is that I have heard that each browser must UNcheck the H.A. I'm sure you'll find out.
Hope that works at least for FF. Let me know if you have time.
I've been checking out Apple TV and Google TV. Just saved the links and some info, haven't had time to go further. I'd prefer Apple TV over Google tho.
I have a 55" HD Sony/Blu-ray Surround Sound Speakers, etc. I hooked up the VGA cable for Internet, and WOW on the Screen/Monitor!! Now I'm thinking about the iPhone 4 with VZ too, on their pre-order list for 2/3/11!
Hard to keep up with the Technology, moving faster today for some reason.
We are under the Snow & Ice warning, getting it now. Hope I don't lose power! If so, I'll be offline for sure.
If I find anything on that H.A. for IE, I'll let you know.
Thanks,
eidnolb

A new Book: Color Management for Digital Photographers

Ted Padova and Don Mason have published a new book: Color Management for Digital Photographers for Dummies (ISBN 978-0-470-04892-4).
As the back cover of the manual states "This book is packed with examples to guide you through understanding color basics, correcting brightness and contrast, getting the exact tone and hue, and creating perfect prints - in full color, of course!" (with the tools available in PSE 4 and 5).
I had the luck to benefit from the excellent experience and the gracious help of Don Mason for a color/brightness adjustment problem in a Dafodill photo that I did not know how to solve on my own. I look forward to learn much more from this book.
Probably other PSE users could also be interested in this book.

Yes, I've tried all of the options: Printer manages color, PSE manages color. All are the same dark prints.
On another conversation on this forum, I read the following. Very discouraging to think that Adobe knows of this problem but won't give me any tech support because too much time has lapsed.
I don't know what "plugs" are--sounds like this user figured out a way around it.
Any advice?
Thanks!
Fran
Re: Color mismatch EpsonR800 and Elements 6
Adobe has admitted that there is a color management issue with PSE 6 for Mac. I have an Epson R1900 and I am now getting acceptable color-managed prints by allowing the Epson Printer driver to manage color management (ie; color management in PSE 6 turned off). The Epson Photoshop Plug In also works well with PSE6 and ICC profiles; however, I have yet to solve 2 problems with this particular plug in: (1) How to get the program to capture 3rd party ICC profiles and (2) how to print borderless prints. If anyone has seen a user guide for this particular plug in, I would be grateful to know how to download it.

Color management for flash galleries

I have recently found out that Flash 10 (currently in beta) supports color management (finally!). However, for it to work it needs to be enabled by the flash application itself. Therefore, I'd like to request the Lightroom team to enable color management for the LR2 flash web galleries.
Thanks for reading!
Simon

Bill,
I'm having the same problem. My exported web galleries are all shifted to the red.
Here's an example: http://venture-multimedia.com/photoshoots/jim/index.html
The guy looks like he has a sunburn. In lightroom he looks fine. I checked on two diff computers and the web gallery looks red on both, yet in lightroom it looks fine.
Just switched to Windows 7 and I'm wondering if that has somthing to do with it.
Suggestions please?!?!?!

Color management for the umpteenth time

I am flummuxed by color management. I have read everything about it and still I have mixed results. Lets start at the basics:
1)I have a Canon pixma 6600d printer
2)I have calibrated by lcd monitor with Huey.
3)I use elements 5.0
4) I have assigned pictures for Adobe rgb.
5) I have read the instructions from Steves Digicam which recommends that I make the source adobe rgb and the target the paper profile that I am using. I am using the correct paper profile.
6) In Print preview, I set the color adjustment to manual, say no to icm, and none to media. This is according to the instructions of all color management gurus.
Some interesting things are happening. When I print a picture file that is Dng (adobe camera raw), the print looks terrible.Too much saturation. heavy magenta, etc. When I print a jpg file of the same picture, the result is much better although not the best. The best match is for one of 2 options. 1)Turn off icm in pe5, use printer color management. or 2) leave on Adobe rgb in pe5. In print preview: set source to adobe rgb. In printer profile, set to adobe rgb and relative colormetric. In Print driver, set color adjustment to auto. These are the most satisfying results.
Questions:
1) Are there problems in printing from a dng file or should I always try to print from a jpg file on my 6600d?
2) If I am using printer color management, should I always turn off color management in pe5 edit?
3)Is there anything else I haven't thought of that explains why I am having lousy results using the correct canon paper profiles in the print preview screen?
Thanks. I know this has been covered a million times.
Andy

Andy....
1. Same as Source - The data that's sent to your Printer is still the data that was created for the Colour Space of the Image. In your case the Source Space indicates sRGB. So sRGB colour numbers get sent to the printer.
What doesn't get sent is any profile information i.e there is nothing to tell the printer your sending it to that the colour space is sRGB. This means that if the printer is to perform colour management, it can't because it doesn't know the source profile - although there may be an option in the Printer Driver to force it to a preset.
2. In some Epson Printer Drivers there are two or more settings for Colour Management and yes they are confusing and I don't think consistent across the range.
I can't tell you all the possibilities but on my R2400, the ICM checkbox turns on Colour Management in the printer and then you have to select a bunch of other options about input profile, rendering intent, and output profile e.g. for the paper/ink type etc, etc,
However, by checking ICM ( on the R2400) it also makes visible an option called No Colour Adjust and by checking this it turns OFF colour management.
So, yes confusing, ICM appears to turn CM ON and then NCA turns it OFF. If this is the setting you use then in Elements you have to select a Print Profile that matches the printer/paper/ink i.e one of the Epson profiles.
3. The Printer Colour Management setting tells Elements to do no Colour Management but it will pass source data to the printer along with a profile.
Elements wont convert the Source Colour Space to the Printer/Paper Colour Space. The assumption then is that you set the Printer Driver accordingly to do the Colour Management Conversion. This might typically be to check ICM and select those features I mentioned in #2.
4. As for the R380 - I can't say what settings that have but take a look at the link below for more info about setting up Epson Printers.
It shows the R800 but the info may be similar for your 380
http://tech.epson.com.au/downloads/message.asp?platform=&techtips=techtips&EmailAdd=&Metri cIDReturned=1044920&submit=Search+%3E%3E&sCategory=Inkjet&id=stylusphotor800
Colin

Color Management for Epson printer using Photoshop Elements 6

I have consistently dark prints when using my new Epson workhorse 1100. It prints fine from iPhoto but not from Photoshop Elements 6. The Epson people say it's an Adobe problem. The Adobe people won't help, as it's not under warranty. I am interested in settings in PSE6 or on my Mac OSX. Or, what's a profile and how do I set it? Thanks!!

Yes, I've tried all of the options: Printer manages color, PSE manages color. All are the same dark prints.
On another conversation on this forum, I read the following. Very discouraging to think that Adobe knows of this problem but won't give me any tech support because too much time has lapsed.
I don't know what "plugs" are--sounds like this user figured out a way around it.
Any advice?
Thanks!
Fran
Re: Color mismatch EpsonR800 and Elements 6
Adobe has admitted that there is a color management issue with PSE 6 for Mac. I have an Epson R1900 and I am now getting acceptable color-managed prints by allowing the Epson Printer driver to manage color management (ie; color management in PSE 6 turned off). The Epson Photoshop Plug In also works well with PSE6 and ICC profiles; however, I have yet to solve 2 problems with this particular plug in: (1) How to get the program to capture 3rd party ICC profiles and (2) how to print borderless prints. If anyone has seen a user guide for this particular plug in, I would be grateful to know how to download it.

Color Management for PDFs in Acrobat

I'm preparing a PDF where all images are in AdobeRGB(98)
but without embedded profiles.
The global Output Intent is AdobeRGB(98).
1. Is this Output Intent profile embedded ?
My standard settings in Acrobat Professional 7 are:
RGB: sRGB
CMYK: ISOCoated
Gray: Black Ink ISO Coated
Output Intent overrides working spaces (checked)
In my environment the images are shown correctly,
which means that sRGB is replaced by AdobeRGB(98).
What happens for average users who have only the free
Acrobat Reader ?
2. Is there any Color Management in 'Reader' ?
Best regards --Gernot Hoffmann

Gernot, "1. Is this Output Intent profile embedded ?" In this particular PDF, the answer is 'yes'. I Opened the PDF with a demo of PDFCanopener and I saw, inside the DestOutputprofile: <pre> <code> Cos Type: Stream Indirect Object: ID: 953 Generation: 0 Stream Bytes: 281 Decoded Bytes: 560 Encoding: PDFText <Start Stream> 0ADBEmntrRGB XYZ Ï acspAPPLnone öÖÓ-ADBE cprtü2desc0kwtpt bkpt°rTRCÄ gTRCÔbTRCärXYZô gXYZbXYZ textCopyright 1999 Adobe Systems Incorporated descAdobe RGB (1998) XYZ óQÌXYZ curv3curv3 curv3XYZ O¥üXYZ 4 ,XYZ &1/¾ <End Stream> </code> </pre> And PitStop can extract the profile. If you open picture by picture with Photoshop, no one has an ICC profile assigned. Same in Acrobat-PitStop: Plain RGB with no profile. Hope this answers question(1). PS. I inserted some carriage returns in the code as it seems to defile the forum display.

Color management for web and print.

Hi there. I would like to post my images and have them print ready for clients. When I read about both of these I find one thing for web and one thing for print. I don't want to edit them twice. What would you suggest for easiest workflow? I like to post the images in an online gallery for my clients and if I really like them maybe use on my homepage. Do I have to edit twice or what is the optimal setting for a photographer. I do mostly portraits --family, baby, couples, etc.
I am pretty well versed in actual editing processes but my understanding in this portion is still lacking. I am trying prophoto rgb on photos today, but will this compromise my online quality?

brwmmw wrote:
…I knew of this option but did not know if it was optimal quality…
You define the quality of the saved image in the Save for Web and Devices dialog box.
brwmmw wrote:
…I have just been… using same files for web and print. I wanted to increase quality across the board in print and web…
That is absurd! (Sorry.) By doing that you are generating unconscionably and unnecessarily large image files. You're clients won't like that.
Remember that you have no control over how anyone sees your images on the web. Something like 97% of Internet users are running non-color-managed web browsers and uncalibrated monitor.
You and you're clients are best served when you stick to the lowest common denominator, namely sRGB images, for web.
brwmmw wrote:
…What mode do you use for prints?…
Personally, I like to stay in 16-bit ProPhoto RGB when I print my images myself. If sending them to a pro lab, I discussed it with the lab techs. But I have gathered a lot of experience by now. One really has to know exactly what one's doing to edit in ProPhoto RGB and stay in that color space. If sending my images to a cheap lab like Costco, I stick to 8-bit tagged images that I soft-proof with the specific printer profile that will be used by the local store.
You should—and probably do—know that ProPhoto RGB has a very wide gamut that includes colors that cannot be printed by many printers, and it's up to you to compensate for that. If you run into problems with ProPhoto RGB consider converting to Adobe RGB for print. Make sure the printer drivers that will be used to print actually support 16-bit printing, otherwise convert to 8-bit.
Since you're a pro, I would warmly recommend you watch the video tutorials comprising the "From Camera to Print - Fine Art Printing" series by Jeff Schewe and Michael Reichmann, that are/were available for download from the Luminous Landscape. They're working on a new 2011 edition, but the 2008 edition was just superb. Best $35 or so I've spent in a long time.
http://www.luminous-landscape.com/videos/camera-print.shtml
Wo Tai Lao Le (no connection to Adobe or Schewe/Reichmnan/Luminous_Landscape.)
我太老了

Looking for detailed literature on Aperture3 color management for fine art printing

I am looking for a coherent , cohesive book or tutorial on Aperture 3 color management capability for fine art printing. Thanks.

Sad to report: does not exist, or if it does, is a closely held secret (by, imho, a coven of eyeless warlocks).
Color on OS X is likely -- just imho -- going to go through a transition which is not going to be helpful, in the short term, for Mac users for whom color is a vital part of their work. X-Rite has, afaict, cast their lot with Adobe. ICC profiling looks like a dead end at this point. Apple is either going to have to leap-frog the competition, or use their technology.
One of the best resources I know is North-Light Images. Up-to-date, Aperture-specific, authoritative information on printing is rarer than superb photography.

Installing a printer color management for my mac using cc

Am having trouble printing, I am told I have no color management programme for my mac. What do I download?

You don't download anything. This is a configuration thing. Start by reading this and then take it from there using the links provided and an expanded web search:
My colors look different outside Photoshop. | Mylenium's Error Code Database
My printed colors look wrong. | Mylenium's Error Code Database
Mylenium

Color management for poster design?

I'm making a poster in CS6 that is composed of text, graphics and some photos that I am importing.
1. How do I decide if the .PSD should be a sRGB or Adobe RGB file? Is this based on the photos I'm importing or is it based on how it will be printed?
2. Does the quality of my image degrade each time I shift from sRGB to Adobe RGB?
Thank you!

The red arrows point to out of gamut warnings (gray areas).
I have to stop here. Teaching someone Photoshop from scratch or step by step exceeds the scope of this or any other forum.
You cannot learn Photoshop from scratch in a forum, question by question.
As I've typed countless times over the years, Photoshop is a professional level application that makes no apologies for its long and steep learning curve.
Your needs far exceed the scope of this forum.
To start learning, take a class in your nearest community college or similar educational institute, watch the Adobe video tutorials on this site, take a subscription to lynda.com, etc. There are many learning tools out there, just Google "learning Photoshop".
Good luck (and please remember this is a user site. I do not work for Adobe).
Remember, you are not addressing Adobe here in the user forums. You are requesting help from volunteers users just like you who give their time free of charge. No one has any obligation to answer your questions.

Color management for Web Designing ?

I want to know what is the best settings for Web design to use sRGB or Adobe RGB ?

razorxdev wrote:
...most people seem to have more advanced monitors capable of wider gamuts...
Hmmm... rather than just saying that most people seem to have advanced monitors, how about presenting some statistical facts on how many are using wide gamut displays?
sRGB is the lowest common denominator. Most every display should be able to render at least that gamut. Catering to the lowest common denominator is what web design is all about (ie: MSIE).
Wide gamut displays certainly change things for a web designer but they cannot (and should not) change things for everyone, including the majority that are still limited to sRGB.

Trying to Understand Color Management

The title should have read, "Trying to Understand Color Management: ProPhoto RGB vs, Adobe RGB (1998) my monitor, a printer and everything in between." Actually I could not come up with a title short enough to describe my question and even this one is not too good. Here goes: The more I read about Color Management the more I understand but also the more I get confused so I thouht the best way for me to understnand is perhaps for me to ask the question my way for my situation.
I do not own an expensve monitor, I'd say middle of the road. It is not calibrated by hardware or any sophisticated method. I use a simple software and that's it. As to my printer it isn't even a proper Photo filter. My editing of photos is mainly for myself--people either view my photos on the net or on my monitor. At times I print photos on my printer and at times I print them at a Print Shop. My philosophy is this. I am aware that what I see on my monitor may not look the same on someone else's monitor, and though I would definitely like if it it were possible, it doesn't bother me that much. What I do care about is for my photos to come close enough to what I want them to be on print. In other words when the time comes for me to get the best colors possible from a print. Note here that I am not even that concerned with color accuracy (My monitor colors equalling print colors since I know I would need a much better monitor and a calibrated one to do so--accurately compare) but more rather concerned with color detail. What concerns me, is come that day when I do need to make a good print (or afford a good monitor/printer) then I have as much to work with as possible. This leads me to think that therefore working with ProPhoto RGB is the best method to work with and then scale down according to needs (scale down for web viewing for example). So I thought was the solution, but elsewhere I read that using ProPhoto RGB with a non-pro monitor like mine may actually works against me, hence me getting confused, not understanding why this would be so and me coming here. My goal, my objective is this: Should I one day want to print large images to present to a gallery or create a book of my own then I want my photos at that point in time to be the best they can be--the present doesn't worry me much .Do I make any sense?
BTW if it matters any I have CS6.

To all of you thanks. First off yes, I now have begun shooting in RAW. As to my future being secure because of me doing so let me just say that once I work on a photo I don't like the idea of going back to the original since hours may have been spent working on it and once having done so the original raw is deleted--a tiff or psd remains. As to, "You 're using way too much club for your hole right now." I loved reading this sentence :-) You wanna elaborate? As to the rest, monitor/printer. Here's the story: I move aroud alot, and I mean a lot in other words I may be here for 6 months and then move and 6 months later move again. What this means is that a printer does not follow me, at times even my monitor will not follow me so no printer calbration is ever taken into consideration but yes I have used software monitor calibration. Having said this I must admit that time and again I have not seen any really noticeale difference (yes i have but only ever so slight) after calibrating a monitor (As mentioned my monitors, because of my moving are usually middle of the road and limited one thing I know is that 32bits per pixel is a good thing). As to, "At this point ....you.....really don't understand what you are doing." You are correct--absolutely-- that is why I mentioned me doing a lot of reading etc. etc. Thanks for you link btw.
Among the things I am reading are, "Color Confidence Digital Photogs Guide to Color Management", "Color Management for Photographers -Hands on Techniques for Photoshop Users", "Mastering Digital Printing - Digital Process and Print Series" and "Real World Color Management - Industrial Strength Production Techniques" And just to show you how deep my ignorance still is, What did you mean by 'non-profiled display' or better still how does one profile a display?

Invalid Color Management in Lightroom? (RAW)

I've noticed the strange thing, how Adobe Camera RAW 4.1.1 displays the same image differently in Photoshop CS3 & Lightroom 1.4.1
Here are the screenshots from both programs:
What I've got in Lightroom/develop mode:
http://www.imagebam.com/image/956c3d6537871
What I've got in Photoshop:
http://www.imagebam.com/image/17a67c6537874
Notice the reds on the face and oranges on the trees on the background. 1) Face on second, photoshop variant is more reddish. 2) The contrast differs as well!
3) There is more orange on the leaves on the second image.
That's all happens in the preview in Lightroom - if I export image as a JPEG and open it in Photoshop - the images will be the same. But BEFORE the export they're DIFFERENT! What's wrong?
(Image is shot on Sony Alpha 350, white balance and all the settings in Camera RAW are the same in two programs).

>yes they are, but in practice PDF causes lot's of bugs.
My experience is opposite in that pdf is usually the only thing that actually works for multipage documents and things containing vector graphics. For single page photos of course tiff always works, but there are lots of clueless operators that do not know their behind from a color profile.
>In my experience colors will be different even for an eye of a consumer. On some printers red will be more reddish, on others green more greenish etc. The contrast will differ either. Maybe you and we use different printers. BTW I work on Windows, maybe that's the point.
I have always had basically perfect results. There was a time when Lightroom interacted wrong with printer drivers when you used profiles inside of the program instead of having the printer driver manage for you. This has long been fixed. Of course there are subtle differences between printers and it would be good if Lightroom had some sort of soft proofing to judge this in advance. The differences are usually pretty minor though nowadays.
>Well, Noritsu, as I know, for example, uses its own color management profile, which you cannot tune even in Photoshop. If you use sRGB, it will be ignored, and you'll get a very low contrast print with desaturated color and you have to be there when it's printed to tune it with the lab assistant. Usually they do it themselves ... well... good. I have SOME good experience with Costco. But for many cases I can't get my colors and contrast without being there when it's printed. And it depends on paper - is it metallic, for example, or matte. The picture will be different. The colors will be different. And you can't check it exactly on your monitor being at home, or in office.
I tested this extensively. If you do this right, it is very hard to see the difference between a sRGB print and a print converted to the profile. With well-tuned Noritsus, you get a small difference in oranges, and a tiny difference in greens - independent of the paper you use. This is the whole point of these machines. If you feed them sRGB, they should give you great results. Maybe my local costcos is very good, but I doubt they are very different from other labs. I tried both Matte and Glossy and they both showed the same result. This is borne out by softproofing in Photoshop that shows exactly the same effect. Note that I wrote about using lab profiles with Lightroom extensively and always tell people to use the profile, but in reality it really is not that important.
See for example: http://lagemaat.blogspot.com/2008/05/great-prints-from-labs.html
If you see large differences in contrast and saturation, there really is something wrong with your calibration workflow or your lab. FOr good prints, the only thing they need to do is to turn off their auto color correction, which with most labs you can do automatically in the online submission pages. I should tell you that you do have to judge prints under good lighting. Often these differences are simply caused by one day being sunny and the other overcast when you walk out on the parkinglot and take out your prints. This is not a real difference. Use a good high color rendering index lamp of high color temperature and you will see that they were the same. My local costcos is calibrated by drycreek photos every month and the profile hardly changes at all over time.
>I don't know, Jao, maybe your point in photography is different, and you don't pay so much attention on colors. These things are subjective! Maybe you pay more attention on other components of photo. In my experience it takes lots of time to prepare a 40"x30" photo for print and then it takes more time and money to colormatch it.
Actually my work is almost always about color. Perhaps I don't sweat it as much. I'd really like Lightroom to have some kind of soft proofing though showing how anal I am about color. I don't use costcos for prints larger than 12x18 as they don't do it locally, but I usually use smugmug's lab (EZprints) for the really large prints. They color manage for you and supply a profile that you can soft proof to if you want. They also appear to scale and sharpen the prints somehow. I've always had outstanding results from them and you can send back the images that you don't like at no cost, although I have never had to do that. I also use smugmug for galleries that clients can order from directly. They have always been very happy with the prints.
>And I work in Windows, maybe your Mac does it better, maybe that's the point of my sad story. But Windows is my karma for many reasons.
The point maybe, also, you print every time on the same printing hardware in Costco - that can explain it all.
I have been happy with my costcos and with EZprints, but I doubt that it is much of an issue. As said, I don't use inkjets very often as they are so darn expensive and annoying to operate but I have never had much issue with bad prints. There is no reason why you could not get windows to behave better. The only thing that you need is to calibrate regularly. I have seen on this forum that windows tends to corrupt monitor profiles over time. The issue is always fixed by recalibrating regularly. Once every month should be plenty.

Printing, Soft Proofing & Color Management in LR 1.2: Two Questions

Printing, Soft Proofing, and Color Management in LR 1.2: Two Questions
There are 2 common ways to set color management in Adobe CS2:
1. use managed by printer setting or,
2. use managed by Adobe CS2 program.
I want to ask how Color Management for Adobe LR 1.2 differs from that in CS2?
As is well known, Color Management by printer requires accurate printer profiles including specific model printer, types of ink and specific paper. It is clear that this seems to work well for LR 1.2 when using the Printer module.
Now lets consider what happens one tries to use Color Management by Adobe LR 1.2. Again, as is well known, Color Management by printer must be turned off so that only one Color Management system is used. It has been my experience that LR 1.2 cant Color Manage my images correctly. Perhaps someone with more experience can state whether this is true or what I might be doing to invalidate LR 1.2 Color Management.
Specifically, I cant use Soft Proofing to see how my images are changed on my monitor when I try to use the edit functions in LR 1.2. Martin Evening states in his text, The Adobe Photoshop Lightroom Book that it is not possible to display the results of the rendered choices (Perceptual or Relative) on the display monitor. While it is not clear in Evenings text if this applies to LR 1.2, my experience would suggest that it still applies to the 1.2 update even though the publication date of his book preceded this update.
Can someone with specific knowledge of Adobe LR 1.2 confirm that Color Management and Soft Proofing with LR 1.2 hasnt been implemented at the present.
The writer is a retired physicist with experience in laser physics and quantum optics.
Thanks,
Hersch Pilloff

Hersch,
since just like me, you're a physicist (I am just a little further from retirement ;) ) I'll explain a little further. computer screens (whether they are CRT or LCD) are based on emission (or transmission) of three colors of light in specific (but different for every screen) shades of red, green, and blue. This light stimulates the receptors in your eye which are sensitive to certain but different bands of red, green and blue as the display emits, making your brain think it sees a certain color instead of a mix of red green and blue. Printers however, produce color by modifying the reflection of the paper by absorbing light. Their color mixing operates completely differently than displays. When you throw all colors of ink on the paper, you get black (the mixing is said to be subtractive) instead of white as you get in displays (the mixing there is additive). The consequence of this is that in the absence of an infinite number of inks you cannot produce all the colors you can display on a monitor using a printer and vice versa. This can be easily seen if you compare a display's profile to a printer profile in a program such as Colorsync utility (on every mac) or
Gamut vision. Typically printers cannot reproduce a very large region in the blue but most displays on the other hand cannot make saturated yellows and cyans.
Here is a flattened XY diagram of a few color spaces and a typical printer profile to illustrate this. Most displays are close to sRGB, but some expensive ones are close to adobeRGB, making the possible difference between print and screen even worse.
So, when the conversion to the printer's profile is made from your source file (which in Lightroom is in a variant of prophotoRGB), for a lot of colors, the color management routine in the computer software has to make an approximation (the choice of perceptual and relative colorimetric determine what sort of approximation is made). Soft proofing allows you to see the result of this approximation and to correct specific problems with it.

Blurb color management for JPG/TIFF

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