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Author Topic: Why change in Histogram from Lightroon to Photoshop?  (Read 9573 times)
ChuckZ
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« on: October 22, 2009, 05:21:21 PM »
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My typical workflow is to first download my memory card into Lightroom2, set white balance, exposure, etc then export to PhotoshopCS4 for further work. In Lightroom, the histogram will show no clipping of the highlights, but once it is in Photoshop, the color histogram often shows clipping, typically the red channel. Why is that and is there some way to change settings so that the histogram is the same in each program? Thank you very much for any thoughts on this situation.
Chuck
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Guillermo Luijk
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« Reply #1 on: October 22, 2009, 05:35:12 PM »
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LR displays a ProPhoto RGB based histogram (i.e. a very wide colour gamut), no matter the output colour profile chosen. When exported to Photoshop, the conversion takes place and this may clip some information to 0 or saturation that will obly be visible once in Photoshop.

All this seems quite stupid, specially since ACR has always disaplayed histograms according to the chosen output colour profile, preventing disgusting surprises.

BR
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ChuckZ
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« Reply #2 on: October 22, 2009, 06:08:22 PM »
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Quote from: GLuijk
LR displays a ProPhoto RGB based histogram (i.e. a very wide colour gamut), no matter the output colour profile chosen. When exported to Photoshop, the conversion takes place and this may clip some information to 0 or saturation that will obly be visible once in Photoshop.

All this seems quite stupid, specially since ACR has always disaplayed histograms according to the chosen output colour profile, preventing disgusting surprises.

BR

Thanks. Surely enough when I change the Export Color Space to ProPhoto, the histogram looks about the same in both programs.  Most of my images go on the web, so the only solution I can think of is to make my adjustments in Lightroom so that there is enough space between the highlights and the end of the histogram chart to take into account the change in color space.  Are there any other methods to compensate for the color space change?
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ChuckZ
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« Reply #3 on: October 22, 2009, 06:11:54 PM »
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forgot to say that the color space I am exporting to in Photoshop is sRGB
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Mark D Segal
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« Reply #4 on: October 22, 2009, 06:22:24 PM »
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Quote from: ChuckZ
forgot to say that the color space I am exporting to in Photoshop is sRGB
That's the first thing I thought of when I read this problem and this is obviously the issue. sRGB is a MUCH narrower colour space than ProPhoto used in LR, so OBVIOUSLY if you export an image which just fits a ProPhoto space in LR to Photoshop with sRGB space there MUST BE clipping. Change your Photoshop working space to ProPhoto and the problem will evaporate.
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Mark D Segal (formerly MarkDS)
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tho_mas
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« Reply #5 on: October 22, 2009, 06:29:16 PM »
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LR doesn't display the histogram of the output color space???
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Mark D Segal
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« Reply #6 on: October 22, 2009, 07:09:29 PM »
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LR displays the histogram of its native working space, which is akin to ProPhoto RGB. (See Martin Evening's Lightroom 2 book, page 255).
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Mark D Segal (formerly MarkDS)
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pegelli
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« Reply #7 on: October 23, 2009, 12:17:47 AM »
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Quote from: tho_mas
LR doesn't display the histogram of the output color space???

LR doesn't know the export color space until you actually export or do the "edit in photoshop" or "edit in other program" options, and the defaults for those can be different. I hope the soft proofing everybody is talking about wilso cover exports or edits, and not just printing.

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pieter, aka pegelli
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« Reply #8 on: October 23, 2009, 10:11:16 AM »
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Quote from: MarkDS
LR displays the histogram of its native working space, which is akin to ProPhoto RGB. (See Martin Evening's Lightroom 2 book, page 255).
Thanks for the hint. I won't even have look at LR itself as long as they are not able to incorporate full-grown color management. I wasn't aware that the implementation of the "export" profiles is that rudimentary... In Camera RAW (Photoshop) the historgram is reflecting the 4 output profiles. And in Capture One, of course, the histogram reflects the output profile (any kind) as well.
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Mark D Segal
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« Reply #9 on: October 23, 2009, 12:48:25 PM »
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No - in Camera Raw the histogram adjusts to the chosen working space. That is not the same thing as "output profiles", which would normally refer to monitor profiles or a printer profiles. Nonetheless I agree it is helpful to work with a histogram adjusted to the boundaries of the chosen colour working space. As I always work in ProPhoto straight through to print this isn't an issue which has exercised me. I re-adjust duplicate files converted to JPEG for email or web as needed.
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Mark D Segal (formerly MarkDS)
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digitaldog
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« Reply #10 on: October 23, 2009, 01:23:01 PM »
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Quote from: MarkDS
LR displays the histogram of its native working space, which is akin to ProPhoto RGB. (See Martin Evening's Lightroom 2 book, page 255).

LRs Histogram represents “Melissa RGB” which is ProPhoto primaries with a 2.2 TRC gamma. That’s not the underlying color processing space (that be ProPhoto primaries with a linear TRC gamma). So you’re basically looking at a histogram that’s not based on anything you’ll ever see or use outside of LR. Its too bad LR doesn’t behave like ACR where the Histogram is based on the actual output encoding color space you pick in the workflow options. Problem is, users export to all kinds of output spaces in LR so the “rational” here is, we’ll just show you a histogram that’s not based on anything real <g>. My suggestion would be to allow a user to option click on the histogram and inform it what space you’re working with albeit, you might export to some other space. I’d personally far prefer the histogram (and the RGB percentages which are now also Melissa RGB) to be in ProPhoto RGB with the 1.8 TRC gamma I’ll almost always export to. And if I export images for email in sRGB, no big deal.

We will all have to wait and see what soft proofing in 3.0 looks like and if it updates the Histogram based on what you select (and if you’ll be able to select an RGB working space). In the meantime, there’s just a disconnect between the LR histogram and RGB percentage values and ACR or anything you’ll actually see outside of LR.
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Andrew Rodney
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bjanes
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« Reply #11 on: October 23, 2009, 01:27:43 PM »
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Quote from: MarkDS
LR displays the histogram of its native working space, which is akin to ProPhoto RGB. (See Martin Evening's Lightroom 2 book, page 255).
Or if you don't have Martin's book, you can look at this explanation of the Melissa color space that Lightroom uses. It has the chromaticities of ProphotoRGB but the tone curve of sRGB. I happen to agree with Guilermo that the use of the Melissa color space is misguided. If sRGB is your final destination, serious color clipping can occur and you might not be aware of it. With ACR, clipping in sRGB will show on he histogram and you can then use a wider color space.
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Mark D Segal
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« Reply #12 on: October 23, 2009, 01:32:23 PM »
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Quote from: bjanes
Or if you don't have Martin's book, you can look at this explanation of the Melissa color space that Lightroom uses. It has the chromaticities of ProphotoRGB but the tone curve of sRGB. I happen to agree with Guilermo that the use of the Melissa color space is misguided. If sRGB is your final destination, serious color clipping can occur and you might not be aware of it. With ACR, clipping in sRGB will show on he histogram and you can then use a wider color space.

Well, I don't agree with either you or Guillermo about this, but Andrew has it right - it would be good to see the effect on the histogram of alternative export spaces in LR. The reason why I don't agree with you, and I THINK what underlay the design philosophy of LR, is that one should work in a wide colour space, and 16-bit depth, in order to preserve the maximum amount of image data so that the image could be subsequently repurposed with great flexibility for whatever use thereafter. You can shake down a rich image very successfully - much harder the other way around.
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Mark D Segal (formerly MarkDS)
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Guillermo Luijk
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« Reply #13 on: October 23, 2009, 01:41:11 PM »
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Quote from: MarkDS
The reason why I don't agree with you, and I THINK what underlay the design philosophy of LR, is that one should work in a wide colour space, and 16-bit depth, in order to preserve the maximum amount of image data so that the image could be subsequently repurposed with great flexibility for whatever use thereafter. You can shake down a rich image very successfully - much harder the other way around.
But this is compatible with the philosophy of always displaying the real histogram. So I don't agree with you in that you don't agree with us
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digitaldog
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« Reply #14 on: October 23, 2009, 01:44:19 PM »
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Quote from: MarkDS
Well, I don't agree with either you or Guillermo about this, but Andrew has it right - it would be good to see the effect on the histogram of alternative export spaces in LR. The reason why I don't agree with you, and I THINK what underlay the design philosophy of LR, is that one should work in a wide colour space, and 16-bit depth, in order to preserve the maximum amount of image data so that the image could be subsequently repurposed with great flexibility for whatever use thereafter. You can shake down a rich image very successfully - much harder the other way around.

As an additional option, it might be interesting if Adobe treated us as advanced users by showing the linear encoded Histogram (which would look odd to many newer users to accustomed to non gamma corrected histos).
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Andrew Rodney
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bjanes
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« Reply #15 on: October 23, 2009, 02:21:41 PM »
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Quote from: MarkDS
Well, I don't agree with either you or Guillermo about this, but Andrew has it right - it would be good to see the effect on the histogram of alternative export spaces in LR. The reason why I don't agree with you, and I THINK what underlay the design philosophy of LR, is that one should work in a wide colour space, and 16-bit depth, in order to preserve the maximum amount of image data so that the image could be subsequently repurposed with great flexibility for whatever use thereafter. You can shake down a rich image very successfully - much harder the other way around.

Lightroom Podcast 8 includes a discussion between Mark Hamburg (the chief architect of Lightroom) and Thomas Knoll (the chief architect of Photoshop and ACR) about how the histograms and color info readouts should be handled. Actually, Thomas recommended using the approach that he used in ACR where the user can select the color space, but Mark chose to use the current Lightroom approach for simplicity. So, Guillermo and I are in good company with our opinions.

In another post, Mr. Knoll pointed out that working in a ProPhotoRGB like space can lead to problems with colors that can not be printed nor shown on the monitor and requires a bit of knowledge about color management, rendering intents, etc. With ACR one can use your approach merely by always using 16 bit ProPhotoRGB. However, if you know that the final product will be 8 bit sRGB, it makes sense to render into this space and adjust the colors so that they fit or allow them to clip. The problem with Melissa is that it is neither fish nor fowl.
« Last Edit: October 23, 2009, 02:25:52 PM by bjanes » Logged
bjanes
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« Reply #16 on: October 23, 2009, 02:44:05 PM »
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Quote from: MarkDS
No - in Camera Raw the histogram adjusts to the chosen working space. That is not the same thing as "output profiles", which would normally refer to monitor profiles or a printer profiles. Nonetheless I agree it is helpful to work with a histogram adjusted to the boundaries of the chosen colour working space. As I always work in ProPhoto straight through to print this isn't an issue which has exercised me. I re-adjust duplicate files converted to JPEG for email or web as needed.
Adjusting ProPhoto files for sRGB can be a bit of a problem if there are a lot of out of gamut colors. This can easily be done by experts such as yourself, but may pose a problem for those for whom the Lightroom dumbed down method was chosen. It would be nice if Lightroom used some type of intelligent perceptual rendering intent for converting to sRGB, perhaps akin to PhotoGamutRGB. For those new to color management, I should point out that there is no perceptual rendering with matrix based spaces such as ProPhotoRGB and sRGB even though Photoshop appears to allow it.
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digitaldog
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« Reply #17 on: October 23, 2009, 03:03:01 PM »
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Quote from: bjanes
Adjusting ProPhoto files for sRGB can be a bit of a problem if there are a lot of out of gamut colors. This can easily be done by experts such as yourself, but may pose a problem for those for whom the Lightroom dumbed down method was chosen. It would be nice if Lightroom used some type of intelligent perceptual rendering intent for converting to sRGB, perhaps akin to PhotoGamutRGB. For those new to color management, I should point out that there is no perceptual rendering with matrix based spaces such as ProPhotoRGB and sRGB even though Photoshop appears to allow it.

Its no more or less a problem than moving from any color space. Yes, you clip colors. That’s the net result of using a tiny little sRGB gamut space. Or moving from ProPhoto to an output profile. Something gets lost in the translation. There’s nothing intelligent nor non intelligent auto conversion that will help here (that’s why we soft proof before we output to our printers). Now having ICC V4 support in all RGB working space would be useful as at least we might try differing perceptual intents going from say ProPhoto RGB to sRGB. But anyone who’s toggled from a RelCol to Perceptual soft proof to the same output device but using differing profile packages (where the perceptual mapping is different and based on the profile makers idea of better) still doesn’t guarantee ideal results. Ultimately you have to edit the source while viewing a soft proof.

Considering that the primary reason anyone would move from ProPhoto to sRGB is to post images on the web, its questionable how much work in this rendering is worthwhile. Output to a 20x30 ink jet you’ll sell or hang on your wall, sure. Output to a 1200 pixel web gallery, where many viewing it don’t even have calibrated displays? Not sure this isn’t anything but a solution in search of a problem. Convert using the current tools and move on.
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Andrew Rodney
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tho_mas
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« Reply #18 on: October 23, 2009, 03:34:20 PM »
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Quote from: bjanes
It would be nice if Lightroom used some type of intelligent perceptual rendering intent for converting to sRGB, perhaps akin to PhotoGamutRGB. For those new to color management, I should point out that there is no perceptual rendering with matrix based spaces such as ProPhotoRGB and sRGB even though Photoshop appears to allow it.
PhotogamutRGB is extremely helpful. Though a bit dated regarding newer printers with better differentiation in dark tonal values.
Too, there is a tablebased sRGB profile: http://color.org/srgbprofiles.xalter
The so called "gamut warning" profile also helps a lot as long as you can set it as working space in the RAW converter: http://color.org/prmg_gamutwarning.xalter
The predecessor of the latter profile - based on Gamma 2.2 and with a 5000K whitepoint - can be found here: http://www.colormanagement.de/?page_id=27
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bjanes
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« Reply #19 on: October 23, 2009, 04:07:27 PM »
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Quote from: digitaldog
There’s nothing intelligent nor non intelligent auto conversion that will help here (that’s why we soft proof before we output to our printers). Now having ICC V4 support in all RGB working space would be useful as at least we might try differing perceptual intents going from say ProPhoto RGB to sRGB. But anyone who’s toggled from a RelCol to Perceptual soft proof to the same output device but using differing profile packages (where the perceptual mapping is different and based on the profile makers idea of better) still doesn’t guarantee ideal results. Ultimately you have to edit the source while viewing a soft proof.
By intelligent perceptual rendering, I meant a rendering which takes the gamut of the colors that are actually in the image into account before arbitrarily desaturating colors when there are no out of gamut colors in the smaller space, as explained by Mike Chaney in the referenced review. This type of rendering must by done by the CMM, which needs to look at the image and see if there are out of gamut colors in the original image. Does ICC Ver4 do this?

Softproofing for a wide gamut inkjet can be problematic even with the best monitors which struggle to display the Adobe RGB gamut. If you desaturate the colors until they fit into such a relatively small monitor gamut, you would not be making the best use of your wide gamut printer. Adobe RGB differs from sRGB mainly in the greens, but what if you are printing red?

Quote from: digitaldog
Considering that the primary reason anyone would move from ProPhoto to sRGB is to post images on the web, its questionable how much work in this rendering is worthwhile. Output to a 20x30 ink jet you’ll sell or hang on your wall, sure. Output to a 1200 pixel web gallery, where many viewing it don’t even have calibrated displays? Not sure this isn’t anything but a solution in search of a problem. Convert using the current tools and move on.
Quite a few mass merchant photo processors expect the files to be in sRGB even though that is not the native space of their photo printers because most P&S cameras output sRGB. In such a case, saturated colors having some gradation can be clipped to a nondescript blob in the printed image.
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