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Author Topic: ProPhotoRGB  (Read 22385 times)
digitaldog
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« Reply #60 on: August 05, 2005, 05:38:00 PM »
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The Desaturate feature is a kludge. Yes, you can experiment and probably start to see out of display gamut colors affected while you edit expect the soft proof is now totally off. I don’t know anyone that uses it. Nice try.

I totally gave up on BasICColor based on the behavior of the people running the company. Didn’t even mention them in the book. They run it like a hobby. That said, their chief color scientist (Franz, original from ColorBlind) is a genius and knows his stuff. Can’t write a GUI to save himself but from a technology standpoint, he’s tops. I only wish he’d associated himself with a company that appreciates his talents (someone like X-Rite or GretagMacbeth).
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Andrew Rodney
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Ray
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« Reply #61 on: August 06, 2005, 08:37:30 PM »
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However, maybe we can develop something practical here.  Would you have a suggestion how to deal with said out-of-gamut colors prior to print?

/> De-saturation by means of the Hue&Sat.-tool (in RGB mode) reduces brightness, too.
/> De-saturation by means of the Hue&Sat.-tool (in Lab mode) changes the hue.
/> The Channel Mixer was recommended elsewhere, but I'm not sure how to use it properly for that purpose.

Any “best practice” how to proceed?
This is a good question. I get the impression some contributors to this thread are in the habit of working with (and printing) out of gamut colors in ARGB and therefore see no point in using a ProPhoto profile which will quite likely increase the number of colors which are out of gamut and the degree to which they are out of gamut.

My understanding is, a monitor is calibrated with respect to a standard such as D65 or D50, not a printer profile. Having gone to the trouble of accurately calibrating your monitor, why would you not want to use proof setup, proof colors and gamut warning prior to printing. If you don't use PS' proof colors and gamut warning for final editing prior to printing, then whether you're in ARGB or ProPhoto you are likely to be sending out of gamut colors to the printer; not only that, the print is unlikely to match what you see on the screen because your monitor wasn't calibrated with respect to any particular paper profile. Is this correct?
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Mark D Segal
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« Reply #62 on: August 06, 2005, 09:36:05 PM »
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Jeff, we were both replying in parallel and I think what I said is consistent with what you said and our interventions complement eachother to some extent. Please correct me if I am wrong. One major point you made that I find truly interesting is about the reverse table of the printer profile. I am using Epson's PRO4000 Enhanced Matte profile (being the printer and paper combination I use), because going in the forward direction it remains the best of the four different profiles I have had custom-made. Sounds counter-intuitive, but my eyes tell me it is true, and in the final analysis that is what I rely on. Now, I have also found the softproofing using this Epson profile to be "reasonably satisfactory". By that I mean for those images where there is a large shakedown of contrast and saturation moving from the non-proofed to the proofed version on screen, the print definitely prints in the ballpark of the proofed image, but quite often the shake-down in the print is not quite as dramatic as the soft-proofing indicates it will be. This means that when I, say, tweak Curves at the softproofing stage I do need to be a bit careful not to over-compensate. Questions: (i) do you know whether this kind of experience sounds about right for this Epson profile, and (ii) who makes first-class profiles going foreward and in reverse?
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
Ray
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« Reply #63 on: August 10, 2005, 09:05:05 AM »
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That gamut warning is useless. There’s no reason for you to be messing with hue/sat with this overlay. It predates Photoshop’s use of ICC profiles. The profiles will handle the gamut remapping. Using a desaturation technique like this is in comparison like using a kitchen knife as a screw driver.
So now you tell me  ! What is Adobe doing providing a useless gamut warning? I've been relying on that gamut warning to fine tune my images before printing.

The fact is, my Epson 7600 prints out duller images than what I see on the screen but pretty close to what I see with proof setup and simulate paper white. In order to give the images more punch and get them looking more like the image I previously edited without 'proof colors' ticked, I often apply saturation and/or local contrast enhancement to the point where I start getting a gamut warning (grayed out patches). I'll print with a few specks of gray but not large patches of gray.

Are you saying I should just ignore this gamut warning, switch it off and make the colors as bright and saturated as I like?
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digitaldog
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« Reply #64 on: August 11, 2005, 08:50:21 AM »
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Ray made an interesting point - he says that when soft-proofing, his monitor did not show him the extent of difference in shadow detail that showed up in the prints between two different rendering intents, whereas Gamut Warning did show a difference in the extent of clipping between these rendering intents.
That’s why it’s necessary to:

Setup the soft proof correctly using the simulate check boxes in full screen mode (it produces a more accurate soft proof of the dynamic range of the output)

Insure the output profile is accurate, especially with respect to the soft proof table (the table in the profile that controls the soft proof, not the actual output)

Insure the display profile is good and that the ambient light in the room is matched to display luminance (Lux versus Cd/m2)

That you view the prints under a CCT 5000K box with dimmer that has it’s luminance set to match the display.

Most important in context of using the old Gamut Wanring: be sure the output profile is loaded in a soft proof before invoking. If not, you’re getting a gamut overlay of the CMYK working profile or whatever was last set in Proof Setup. That’s an easy mistake to make. Unlike the Proof Setup where when invoked (Command/Control Y) Photoshop shows you the current output profile being used in the document name, if you just toggle on View-Gamut Warning, you get the overlay but no direct indication of what profile is currently being used for this overlay.
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Andrew Rodney
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« Reply #65 on: August 14, 2005, 10:15:22 AM »
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I remember reading a good article on the saturation rendering intent some time ago. Unfortunately I just can't find the link at this moment. The point that the article demonstrated was that sometimes images can benefit from saturation intent. As the implementation of the saturation intent is vendor specific (just as perceptual is) the quality depends on the package used.

At DryCreek e.g. they pay special attention to their saturation rendering intent.
Quote from their website:
"Our newer profiles (August 2004 and later) feature a Saturation intent that is tuned to provide maximum useable saturation in the prints. If an image will benefit from increased saturation, give the Saturation intent a try. Most profiles either reserve the Saturation intent for PowerPoint-type graphics use or simply map it to the Perceptual intent. Our new profiles are designed to give photographers another technique to get the best prints possible."

Herman
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bossanova808
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« Reply #66 on: August 17, 2005, 02:38:17 AM »
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Talk about pedantry.  Whichever way you shake it 'bigger space = MORE tones" is wrong and "bigger space = different tones" is right.  For any bit depth you care to stick in it!

Anyway, it's a simple point now driven to death so whichever way you choose to say the same thing is fine.  Whatever floats your boat.
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bossanova808
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« Reply #67 on: August 18, 2005, 03:23:35 AM »
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Good to see we all got there in the end.  One of those we all agree, but are using different words type things that forums really seem to suffer from....
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Mark D Segal
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« Reply #68 on: August 03, 2005, 09:34:12 PM »
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Paul, my understanding of this is that it is not only the size but also the shape of the colour space that matters, and different printers print diffrerent gamuts. I am informed that the Epson 4000 - and most likely all the more so the new generation of Epson printers - can reproduce certain hues that are within the ProPhoto gamut but outside the Adobe RGB98 gamut. By using the wider gamut you don't run the risk of losing hues that the printer can handle. It seems there is no downside to this.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
paulbk
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« Reply #69 on: August 04, 2005, 03:44:28 AM »
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re: "When converting this 16-bit (actually 12-bit) image to a printer profile the risk of banding is far less."

Why? The argument for working in 16 bit applies equally to sRGB and ProPhoto.

What we need is a 32 bit printer and 64 bit eyes.
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paul b. kramarchyk
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« Reply #70 on: August 04, 2005, 01:59:32 PM »
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*WAY COOL ALERT*
Interactive Printer, Camera, Scanner, and Monitor Color Gamut Comparisons

Quite possibly the coolest tool on the world wide web.
Cancel all appointments. Click. And enjoy!
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paul b. kramarchyk
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« Reply #71 on: August 06, 2005, 04:55:00 AM »
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>Well, unless you have a new Adobe RGB display, you're STILL not "seeing" everything in the image, what's your point?

You don’t improve anything by adding more unknowns

Not trying to ruffle any feathers here but I'm not going to repeat myself or others. Everything that is relevant in this matter has been said (especially the contributions by Rodney and Schewe). You keep on bringing up this very same argument that has been wiped off the table by numerous replies.

Herman
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giles
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« Reply #72 on: August 06, 2005, 05:34:13 PM »
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I actually went to read up on this article and without going to far, found this:

-->All colour spaces of the same bit depth (typically 8 or 16 bit) have the same total number of tones. That is, a bigger colour space does not mean there are more colours in total!

That’s not really so.

[ much text elided --giles ]

So going back to “That is, a bigger colour space does not mean there are more colours in total” the issue here is saturation of the primary colors (RGB in this case). Yes, R255 in sRGB and ProPhoto RGB share the same number but most certainly not the same scale.
So (assuming I'm following correctly) there are "more colours" in terms of a wider range of saturation which you're speaking about.  But there aren't more numbers to represent these colours (Jeremy's "no more colours in total").

In the case where an image fits within the smaller of any two spaces, operations on that image in the smaller space will be capable of finer changes because the steps between (say) R140 and R141 are closer than they are in the larger space.  Finer changes are a good thing, as there is less chance of introducing banding et al ... right?

Giles
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Mark D Segal
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« Reply #73 on: August 06, 2005, 11:53:51 PM »
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Thanks Jeff. I need to check whether my softproofing is paper white/ink black - its late now - tomorrow. Apart from that - yes perhaps if I were totally ISO 3664 compliant the soft-proofing would be very accurate and all would be well until people look at the print outside an ISO bubble. One then hopes the real world wouldn't have violated it too badly!
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
bjanes
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« Reply #74 on: August 09, 2005, 09:22:16 PM »
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I've followed this thread with great interest and have found the discussions very illuminating. I did read a post some time ago by Thomas Knoll on the Adobe MAC PS forum to the effect that he does not recommend ProPhotoRGB for those photographers who lack a basic understanding of color management and rendering intents. Of course, that doesn't apply to any of us in this discussion  Smiley

As Jeff and Rodney so aptly point out, why throw out colors that you might be able to use at some time or at least control their output? Why not go one step further and use a scene space that preserves more of the full dymanic range of the image? The only such space that I know of is the PhotoYCC that Kodak used for the photo CD, which was proprietary and never caught on, but there must be others. Since they don't seem to be used that much, there must be no advantage but I was just wondering.
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bossanova808
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« Reply #75 on: August 16, 2005, 09:48:42 PM »
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Andrew Rodney wrote:

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-->All colour spaces of the same bit depth (typically 8 or 16 bit) have the same total number of tones. That is, a bigger colour space does not mean there are more colours in total!

That’s not really so. This is a fundamental misunderstanding of what a color space is. So I’ll do a quick copy and paste from some text I wrote:

<here follows a recipe for a cookie>

I'm afraid it isn't a misunderstanding, actually a mis-reading.

Far be it from me to argue with someone far more qualified but I'm actually correct here.  I don't really know how to put it in clearer terms - the maths is quite clear.  Each 16 bit colour space has the same total number of tones in it.  What those tones mean is, however, highly variable.  (The 'scale' in your recipe).  

A colour space is simply a definition of the boundaries and they can be as wide or as narrow as you choose - but the number of items contained within these boundaries never changes unless you change the bit depth representing each item.

The rest is up for (seemingly endless) debate but unless I misunderstand binary, the above is just fact.

I don't want to wilfully disagree, and I don't even want to be that involved in the discussion, but I don't think I suffer from any fundamental misundertstanding.  In this case, anyway!
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Hermie
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« Reply #76 on: August 17, 2005, 03:54:22 AM »
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This is what I'm having trouble following. As I see it a bigger space does not mean more colours. It means the possibility of colors with greater saturation or intensity. The actual possible number of colors is determined by the bit depth. To put it another way, a 24 bit apple can be cut up into 16.7 million pieces, each piece representing a color. A 48 bit apple can be cut up into 68 billion pieces (is that the right figure?), each piece representing a color. The apple is the same in both cases.

With "A bigger space DOES mean more colors.", I meant more colors in the sense of a larger volume/scale in LAB (more saturation etc.).

So I think we are actually agreeing.

>> An image with a given bit depth does not necessarily have the same number of tones. It depends on the image.

Agreed of course.

Herman
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digitaldog
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« Reply #77 on: August 17, 2005, 11:59:16 AM »
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Now if you want to debate that the max red in one color space which is more saturated than another isn’t really “more colors”, OK.
Well, it needs clarifying doesn't it. I get the impression some folks reading this might think a wider range of colors between extremes of saturation translates to a greater number of colors.
Good point. Yes, it’s a tad bit more than semantics. A wider gamut doesn’t provide “more colors” but a wider range of colors. You spread the colors over a wider range and that’s one reason you want to work with high bit data with progressively wide gamut color spaces. And yet the numbers are the same when you define these colors using 256 steps per color channel (for 8-bit). That is R255 isn’t the same color in two different working spaces although they share the same value (which is confusing at first). We’re all used to a unit of something being fixed; “a pint’s a pound the world around.”
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Andrew Rodney
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Mark D Segal
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« Reply #78 on: August 11, 2005, 08:39:18 AM »
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Andrew, as a published authority on this subject people in this Forum are looking up to you for real value-added. When you don't read what you are being told and simply talk past the question raised it is helpful to no one.

Ray made an interesting point - he says that when soft-proofing, his monitor did not show him the extent of difference in shadow detail that showed up in the prints between two different rendering intents, whereas Gamut Warning did show a difference in the extent of clipping between these rendering intents. Either this observation occurs under some arcane conditions, or it means that perhaps the Gamut Warning tool should not be relegated to the scrap heap quite so quickly. This is the issue we asked you to comment on. Of course this is a free enclave so you can say you want, but being relevant would be helpful.
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Mark D Segal (formerly MarkDS)
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giles
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« Reply #79 on: August 04, 2005, 12:15:56 AM »
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It seems there is no downside to this.
Offered without comment, since I'm not qualified to comment, but an article discussing potential downsides:

ProPhoto or ConPhoto?

Giles
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