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Author Topic: Best method to recover a completely clipped channel (LR or PS5) ?!!  (Read 3311 times)
thierrylegros396
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« on: January 04, 2013, 04:44:00 AM »
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What is the best method to recover a completely clipped channel, the 2 others being almost perfect ?!

I've several photos with wonderfull skies, but the red channel only is clipped.

The others are fairly lower, so some areas appears almost uniform.

LR4 sliders don't give good enough results.

Any good ideas are welcome Wink

Thierry
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Redcrown
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« Reply #1 on: January 04, 2013, 02:13:12 PM »
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Need more info and example to be most helpful (raw?, jpeg?, camera model?).

But if you have raw the first thing I'd try is different profiles. Depending on your camera model, the Adobe profiles (standard, faithful, neutral, etc.) can have a big impact on color rendition, especially in the red channel.

That, and the highlight recovery on raw files can go a long way to restoring clipped channels. The highlight recovery function actually uses data in "good" channels to fix bad channels. The highlight recovery in LR4/PS6 is significanly better than in previous versions. But you say you have "PS5", so you may not have the full power of highlight recovery.

Upload a raw file and I'm sure others will have a go at it.
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thierrylegros396
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« Reply #2 on: January 04, 2013, 03:05:35 PM »
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I've restored a lot of clipped photos.

But yellow flowers and reddish skies are among the hardest things to cure.

Yes those are raw files from G15, and I've found ways to improve them, but I want to restore them with the best methods available today.

As often, use of several methods gives even better results.

That's why I ask your help.

Thierry
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madmanchan
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« Reply #3 on: January 04, 2013, 07:14:40 PM »
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I suggest posting an example raw file.
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elied
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« Reply #4 on: January 05, 2013, 04:13:08 AM »
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If those are Raw files, it is highly improbable that in the original capture the red channel is clipped and the green channel is not. It is the white balancing that is causing the red clipping and there are multiple ways to counteract this - the R-G-B curves editor, HSL panel and Grad Filter/Brush being a few of them.
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thierrylegros396
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« Reply #5 on: January 05, 2013, 05:52:19 AM »
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If those are Raw files, it is highly improbable that in the original capture the red channel is clipped and the green channel is not. It is the white balancing that is causing the red clipping and there are multiple ways to counteract this - the R-G-B curves editor, HSL panel and Grad Filter/Brush being a few of them.

For the red sky, you are right !

Lowering the WB to 2500K shows no more clipping of the Red Channel.

But for yellow flowers, I will post a RAW file soon as suggested by madmanchan.
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thierrylegros396
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« Reply #6 on: January 05, 2013, 06:40:51 AM »
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The Raw can be found here

https://skydrive.live.com/redir?resid=82750CF68B57F67E!139

One or two channels are clipped.
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Walter Schulz
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« Reply #7 on: January 05, 2013, 07:04:38 AM »
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No, they are not. Looks perfectly fine to me and PS CS 5.1 supports my opinion. Same in LR 4.3.
I suppose your LR settings are way off or you picked the wrong picture.

Ciao, Walter
« Last Edit: January 05, 2013, 07:09:08 AM by Walter Schulz » Logged
BartvanderWolf
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« Reply #8 on: January 05, 2013, 07:46:15 AM »
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The Raw can be found here

https://skydrive.live.com/redir?resid=82750CF68B57F67E!139

One or two channels are clipped.

Hi Thierry,

A quick look at the file with 'Rawdigger' shows that the file was correctly exposed, slightly more than 1/3rd stop below any clipping. So you could have exposed it a third of a stop more, and still experience no clipping.

Whatever issue you are having, it's not Raw clipping in this file. LR4 also doesn't indicate any clipping. Maybe it's more colorspace/gamut related?

Cheers,
Bart
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FranciscoDisilvestro
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« Reply #9 on: January 05, 2013, 07:56:10 AM »
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Hi,

Bart and Walter are correct, here is the Raw histogram from Rawnalize where you can see that you have at least 1/3 stop headroom

Are you using a sRGB monitor?
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Walter Schulz
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« Reply #10 on: January 05, 2013, 08:17:22 AM »
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Are you using a sRGB monitor?

AFIAK this should only be an issue if "Softproof" is used with a monitor profile.

Ciao, Walter
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FranciscoDisilvestro
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« Reply #11 on: January 05, 2013, 08:31:22 AM »
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AFIAK this should only be an issue if "Softproof" is used with a monitor profile.

Ciao, Walter

Hi, not necessarilly. You might see Clipped or "textureless" colors with a sRGB monitor in areas that are out of the sRGB gamut, which are fine in the Raw image or in a wider color space. This could give the perception of blown channels.
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Redcrown
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« Reply #12 on: January 05, 2013, 10:49:00 AM »
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Thanks for the raw. I'm not familiar with the Canon G15, but this raw shows the most bizzare Adobe profiles I've ever seen. As I guessed in my original reply, the problem with clippiing on this image is all in the profiles.

True, there is no clipping in the raw, as others have shown with a raw analyzer. Far from it, in fact. But load this raw in LR or ACR and significant clipping shows up under the default settings, which use the "Adobe Standard" profile. But shift to any other profile and the clipping goes away.

The other profiles also give major shifts in color. That's common with the Adobe profiles for most camera models, but the shifts in color AND tone curves for this G15 image are greater than anything I've ever seen. Makes me a bit suspicious about the Adobe profiles for that camera.

In fact, if you shift this image to any other Adobe profile (faithful, camera standard, neutral), you can then increase exposure by 1 to 2 full stops before any clipping occurs.

I converted the cr2 sample to DNG and loaded it in the DNG profile editor to look at the tone curves. The base tone curve for the Adobe Standard profile is huge compared to the others. So it's that tone curve that is driving all the values beyond clipping. Looks like the G15 really, really needs custom profiles.
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Walter Schulz
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« Reply #13 on: January 05, 2013, 11:30:25 AM »
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But load this raw in LR or ACR and significant clipping shows up under the default settings, which use the "Adobe Standard" profile. But shift to any other profile and the clipping goes away.

I used "Adobe Standard": No highlight clipping in LR or ACR.

Ciao, Walter
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jrsforums
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« Reply #14 on: January 05, 2013, 11:37:19 AM »
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What is the best method to recover a completely clipped channel, the 2 others being almost perfect ?!

I've several photos with wonderfull skies, but the red channel only is clipped.

The others are fairly lower, so some areas appears almost uniform.

LR4 sliders don't give good enough results.

Any good ideas are welcome Wink

Thierry

What made you think they were clipped in the red?  RAW you submitted had no clipping.  Do you have one which does....that prompted you post in the first place?

BTW...in my experience, opening in LR 4 (adobe Standard profile), all the recoverable channels have been recovered.  If a channel then shows clipped, it cannot be recovered.

John
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John
Redcrown
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« Reply #15 on: January 05, 2013, 11:44:07 AM »
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I need to take back a little of what I said above. The Adobe profiles for the G15 are not that bizzare. In fact, they generate results that are very close to the results that Canon's DPP generates. That is what they are claimed to do and they do it well in this case. I had to run this sample cr2 through DPP to remember that.

But it is still the Adobe Standard profile that is causing problems for the OP. It's a mystery to me how Adobe generates the "Adobe Standard" profiles for every camera model they support. But it appears they use the same base tone curve for every one or them. That base tone curve is very strong (gamma 2.2 I think), and is good reason not to use them as this case demonstrates.
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Walter Schulz
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« Reply #16 on: January 05, 2013, 11:51:09 AM »
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and is good reason not to use them as this case demonstrates.

I cannot follow your jump to conclusion because it is based on poor/incomplete data. Nobody knows what's the thread opener's problem actually is.

Ciao, Walter
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Redcrown
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« Reply #17 on: January 05, 2013, 12:03:14 PM »
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Walter and jrsforums had me confused for a while. I could not understand why they did not see highlight clipping in the red channel. But then I realized it's also a colorspace issue. If you load the OP's raw in ACR with the ProPhoto colorspace as default, there is no clipping, even under the Adobe Standard profile. But if you use any other colorspace (Adobe98, sRGB, Colormatch) there is clipping. I use Adobe98 as the ACR default. Walter and jrsforums must be using ProPhoto.

I'm not suggesting we re-visit the ProPhoto colorspace debate. But in this case, if the OP converts this raw image under ProPhoto plus Adobe Standard he will avoid clipping UNTIL he converts the image to sRGB for web posting, or tries to print it. Then the clipping will return.
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Redcrown
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« Reply #18 on: January 05, 2013, 12:09:58 PM »
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Quote
I cannot follow your jump to conclusion because it is based on poor/incomplete data. Nobody knows what's the thread opener's problem actually is.

Well, I have a conclusion but I didn't jump to it. I did a lot of testing to get good, complete data. The OP's problem is clipping (in the red channel) caused by the combination of using the Adobe Standard profile and Adobe98 or sRGB colorspace. Change the profile and the problem goes away. Change the colorspace to ProPhoto and the problem goes away temporairly.
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Walter Schulz
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« Reply #19 on: January 05, 2013, 12:19:56 PM »
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Yes, this is correct. I use ProPhotoRGB and I'm aware of the clipping issues with aRGB and sRGB (been there, done that).
But the thread opener has a problem in LR, too. And there is no way (known to me, at least ...) *not* to use Melissa RGB in LR. It may be a perception problem as pointed out by Francisco. But we need to wait for more info from the TO.

Ciao, Walter
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