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Author Topic: Adjusting ACR Highlight and Shadow Warning Thresholds  (Read 7674 times)
LDJ
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« on: December 19, 2012, 04:26:30 AM »
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Hi

I'm hoping that Eric Chan or someone else on the Adobe team will be able to answer my question:

Why has the ability to adjust the threshold for highlight and shadow warnings not been included in Adobe Camera Raw? Capture One Pro, Aperture, Phocus, Canon DPP, all have this facility, so I don't understand why it has not been implemented in ACR. The lack of this one feature prevents me using ACR for any images where I have to be sure of highlight values: I need to know when the whites hit 250 RGB (or even less if I want real detail in the highlights) and currently this much more difficult than it should be in ACR.

Is there any chance that this functionality could be included in the next version of ACR because, other than the lack of this (in my view) critical feature, ACR is now a great raw processor and I would like to use it more.

Many thanks

Liam
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Ronald NZ Tan
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« Reply #1 on: December 23, 2012, 02:43:24 PM »
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I agree.

But . . . it isn't a big deal for me, when I sometimes use ACR to process my DNGs from my Canon 7D. I look at the histogram and eyeball the "250" mark. It is not accurate, but as long as my *important* highlight information isn't blown (no red blinkies), I am OK with that. Same for shadows: as long the important shadow are isn't clipped (no blue blinkies), I am OK.

It would be nice to enter a global value and have ACR warn the user when the adjustments pass the set parameters.

I doubt Dr. Eric Chan would reply here. In any case, there is a feature request section on the Adobe website. Email them.
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digitaldog
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« Reply #2 on: December 24, 2012, 10:13:35 AM »
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I need to know when the whites hit 250 RGB (or even less if I want real detail in the highlights) and currently this much more difficult than it should be in ACR.

What makes 250 the magic number (considering the value defining a color or even clipping will change somewhat based on color space)?
ACR does show you full clipping in a number of ways. And you can back off (making a pretty flat appearing image) to 250 based on the current color space if you wish.
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Andrew Rodney
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LDJ
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« Reply #3 on: December 24, 2012, 02:24:56 PM »
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I doubt Dr. Eric Chan would reply here. In any case, there is a feature request section on the Adobe website. Email them.

I may well post on Adobe's feature request section, but I like the LL community so thought I'd post here first. Eric, A.K.A. 'madmanchan', is a regular contributor to the LL forum pages and I have always thought that he is generous and honest with his responses and views; I think it is fantastic that it is possible to engage with one of the key Adobe developers on this forum.

What makes 250 the magic number (considering the value defining a color or even clipping will change somewhat based on color space)?
ACR does show you full clipping in a number of ways. And you can back off (making a pretty flat appearing image) to 250 based on the current color space if you wish.

I don't consider 250 to be a magic number. However, I generally deliver images in the Adobe RGB colour space and, in my view, you can be pretty sure that, no matter what the final printing process, any areas of an image with RGB values of above 250 will not print with much/ any detail.

There is no reason for any image to appear flat: I am not saying that I want the brightest point in an image to be less than 250. I simply want a quick way to know that areas where I want some detail e.g. fabric weaves, are below that level; as I stated in my original post - for real detail I would probably want the RGB values to be much less than 250 (e.g. 240-245 range for white with textural detail). At present, with ACR there is no easy way to do this; I don't want to have to start dropping control points all over an image to verify that areas are below a certain value, it is much easier to be able to simply adjust the highlight warning threshold level.

Kind regards

Liam
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JRSmit
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« Reply #4 on: December 26, 2012, 03:25:12 AM »
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Simply make sure that the histogram does not extend to the right completely. As you say you deliver in aRGB, best if you check the export result to see if the histogram of the converted result is not completely extended to the right. I sometimes do this to make sure that on the print there is no complete white in the image itself, because it will show up due to gloss differential.
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Jan R. Smit
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« Reply #5 on: December 26, 2012, 06:06:21 AM »
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There's no direct way BUT, if you adjust your picture so that nothing is lost, nothing is pure white, when printing the ICC by itself with the perceptual rendering will take care of it, if needed.
Probably it's not what you're looking for, but I don't feel it may change in the short period. Sad
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BartvanderWolf
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« Reply #6 on: December 26, 2012, 10:34:40 AM »
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Hi

I'm hoping that Eric Chan or someone else on the Adobe team will be able to answer my question:

Why has the ability to adjust the threshold for highlight and shadow warnings not been included in Adobe Camera Raw? Capture One Pro, Aperture, Phocus, Canon DPP, all have this facility, so I don't understand why it has not been implemented in ACR. The lack of this one feature prevents me using ACR for any images where I have to be sure of highlight values: I need to know when the whites hit 250 RGB (or even less if I want real detail in the highlights) and currently this much more difficult than it should be in ACR.

Hi Liam,

While it is not exactly what you're asking for, this action may still be of some help.

You can set up the ACR preferences to open your Raw conversion as a Smart Object in Photoshop, and run the action with your preferred clipping indicator settings. When necessary, even after subsequent PS alterations, you can go back to the source and e.g. reduce exposure or highlights/shadows without losing your additional PS edits.

Cheers,
Bart
« Last Edit: December 26, 2012, 10:56:02 AM by BartvanderWolf » Logged
digitaldog
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« Reply #7 on: December 26, 2012, 10:42:46 AM »
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I don't consider 250 to be a magic number. However, I generally deliver images in the Adobe RGB colour space and, in my view, you can be pretty sure that, no matter what the final printing process, any areas of an image with RGB values of above 250 will not print with much/ any detail.

IF you have no control over the conversion, that might be somewhat sound but if the other party is using good ICC profiles, there's no reason for this additional headroom. In fact, many images look significantly better with clipping on either end depending on the image content. Take a look at say Greg Gorman's portraits and his huge disregard for anything approaching shadow detail. Since these are presumably your images, make them look good to your eye, clip or don't clip if you desire and let the output profile map to the black/white values from the source color space.

Bottom line is, clipping is good if it looks good within the image. Images at 5/250 might work out or might look odd or flat. There is no one size fits all set of numbers, images are too complex for that kind of thinking. If it were, machine prints and auto processes would work wonders on all images and anyone who's examined either can tell you YMMV. Photography and processing for print is about rendering the image for the print.
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Andrew Rodney
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« Reply #8 on: December 26, 2012, 07:01:07 PM »
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Being at both ends of the workflow for images to print, I do rgb to cmyk for publishers in my local area.

I would have to agree with DigitalDog, that you the photog, make your images look their best, it's then up to the person, taking the image to print to translate this to paper for the given printing situation, be it fine art RGB or CMYK on a news paper.

Unless you know and inform the person these final steps, they too will make provision for error, should there be an issue. Generally it's the shadows that causes the most issues, together with out of gamut colors on cheaper matted paper.

All the best

Henrik
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jljonathan
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« Reply #9 on: February 24, 2013, 10:14:17 PM »
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Since these are presumably your images, make them look good to your eye, clip or don't clip if you desire and let the output profile map to the black/white values from the source color space.
Bottom line is, clipping is good if it looks good within the image.

Here, Here. This makes complete sense. Thank you, Sir.
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LDJ
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« Reply #10 on: February 25, 2013, 05:25:28 AM »
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Hi

Apologies for the slow response. Thanks all for taking the time to give your views. Thanks also to Bart for the link; although this might not be what I am looking for regarding ACR, it will definitely come in handy for Photoshop work.

Even though some interesting views have been given in this discussion, I still feel that the ability to change the clipping threshold levels is a strange omission by Adobe. On reading the responses, I believe that by stating a number (250) I inadvertently managed to direct the discussion away from the core issue I was raising. I am certainly not advocating that it is necessary for all pixels to be below 250; as others have said, if it looks good to clip pixels to 255 or 0, then do it. However, I still believe that it is beneficial to ensure that areas where detail is required in the highlights (e.g. white woven fabric) do not get near 255. I'm not going to give any numbers as they are obviously not rigid and what appears white in an image is affected by the tonalities and contrast in the image as a whole. All I want is a quick way to verify that areas of an image do not exceed what ever level I decide on for white (or not white, as the case may be); surely others find it useful at times to be able to check that areas of an image fall above or below a certain value, not matter what that value.

I appreciate what Henrik and DigitalDog have to say but, in my workflow, I am hardly ever involved in the process of taking an image to print beyond delivering the files to a client. From experience, I know that the CMYK conversions are often not done well and, although I guess you could say that this is not down to me, I want my images to look good when they are seen by others, who will not know or care that  my images were delivered looking good only for them to look bad on paper through poor conversion. Given this, I do like to leave a little headroom in areas where I want detail.

Finally, regardless of my methods, in my opinion, good software design should be about enabling the end user. Adobe's decision to omit the ability to specify clipping levels does the opposite of this: as stated in my original post, Capture One Pro, Aperture, Phocus, Canon DPP (and many others) all have this facility and I know many other photographers and retouchers who make regular use of it and have incorporated it in their workflow, so I just wonder why Adobe does not provide it in ACR.

Thanks
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BartvanderWolf
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« Reply #11 on: February 25, 2013, 06:05:47 AM »
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Finally, regardless of my methods, in my opinion, good software design should be about enabling the end user. Adobe's decision to omit the ability to specify clipping levels does the opposite of this: as stated in my original post, Capture One Pro, Aperture, Phocus, Canon DPP (and many others) all have this facility and I know many other photographers and retouchers who make regular use of it and have incorporated it in their workflow, so I just wonder why Adobe does not provide it in ACR.

Hi,

I agree, it should be a user definable preference setting. I do understand that there may be some technical challenges in a program like Lightroom because there are no real RGB values until after output profile conversion.

Cheers,
Bart
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elied
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« Reply #12 on: February 25, 2013, 08:00:22 AM »
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It doesn't have to be RGB based. It could be 99%, 98%, etc. A flick over to soft proofing will indicate what the RGB equivalents will be.
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« Reply #13 on: February 25, 2013, 09:20:57 AM »
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From experience, I know that the CMYK conversions are often not done well...

Yes but the issues are rarely due to clipping. It's due to the incorrect flavor of CMYK for the output which can make the difference between piece of art and a piece of s%$t! Make the RGB data look as good as you can on a calibrated display. Without the proper CMYK profile and then a soft proof, you're flying blind once you pass off that lovely RGB data.
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Andrew Rodney
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LDJ
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« Reply #14 on: February 26, 2013, 09:42:28 AM »
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Hi DigitalDog

Thanks for your further input. I have a copy of your colour management book and found this section in the chapter 'Working by the Numbers' and wondered what you meant by it:

"When working with numbers, at what value should I set my highlight and shadows?The output profile will play a role in the resulting values of both. Since you might be making multiple print/output conversions, it’s important to leave some headroom in the master RGB working space document. I generally advise users to scan a bit flat to leave some numeric values and avoid clipping the data. If you are shooting with a digital camera, this is a bit trickier unless you have total control over the lighting of the subject. I hate to make general numeric recommendations since “your mileage may vary,” but consider keeping the specular highlights around 248 to 250 in all channels, and the darkest black around 5 to 8 in all channels. This will allow the conversion into print/output space headroom to avoid clipping."

Would the RGB files I submit to clients not be considered as 'master RGB working space documents', considering that the images are often used for a variety of different media and that the clients/their repro houses are dealing with conversions to the print/output spaces?

Although I try to leave a little 'headroom' in my delivered files, I certainly don't keep specular highlights at around 248 to 250 and allow them to go to 255.

Regards

LDJ
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digitaldog
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« Reply #15 on: February 26, 2013, 09:49:28 AM »
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Would the RGB files I submit to clients not be considered as 'master RGB working space documents', considering that the images are often used for a variety of different media and that the clients/their repro houses are dealing with conversions to the print/output spaces?

Depends on the client and what they expect to do with the data. I work in 16-bit ProPhoto RGB as my rendered master and there are few clients I'd provide that color space to and it would also be based on what the client is going to do with the data (print on a 4 color press or a high end ink jet?). It depends on if I have an actual output profile I can use to soft proof before sending the data to the client. If you're flying blind, you probably want a little headroom. If you have the output profile to target the soft proof, then just view the image as it soft proof's and tweak there.

IF I had for example an image shot on a white bkgnd and wanted that white, I'd blow that out in any case. Or I might block up shadows if it makes the image look better no matter the output.
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Andrew Rodney
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LDJ
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« Reply #16 on: February 26, 2013, 10:12:12 AM »
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Well, my working space of choice is Adobe RGB and nearly all my clients request that images are delivered in that colour space. As stated previously, I very rarely have any involvement in the conversion of the images to final print/output colour space after delivery; clients often use images across a range of media, from web to newspaper to glossy magazine, which is why I like to leave a little headroom in my files to accommodate these different output requirements, and which is why I would like ACR to have the option to set the clipping thresholds so that I can make sure that I leave this headroom in any raw conversions with ease.

I am sure that implementing this functionality in ACR would require a bit of work, but the software development guys/gals at Adobe are quite clearly all rather intelligent and good at coming up with programming solutions...
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Ellis Vener
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« Reply #17 on: February 26, 2013, 10:29:24 AM »
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If you choose Adobe RGB(1998) in Lightroom's softproofing feature you will be able to see where you are clipping.
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« Reply #18 on: March 13, 2013, 05:34:21 PM »
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I'm no expert and perhaps I should rather stay lurking in the corner but what I usually do is hold the option key while sliding the Black and the White controls until the black just starts showing and the white in turn. That way you know the limits on either end.
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