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S
short73
Inspiring
February 20, 2018
Answered

Does highlight recovery add neutral density?

  • February 20, 2018
  • 3 replies
  • 1316 views

Hi,

I know this is not new in the latest process version of camera raw, but I'm noticing in some images where a section is completely blown out, it can be made to appear as "grey / neutral tone". For example, a sky with no detail, even when I adjust the exposure slider down to the lowest exposure (-5) and I get NO additional detail in the sky, I do get a reduction in the tonal value (even making this area quite dark).

I'm assuming the camera raw is "adding" neutral density to the highlight area at some point? Where does this "addition" of neutral tone start in camera raw..? At first I thought it was only the "Highlight" slider, but it seems the exposure slider also adds it. How do I know when I have the maximum detail from the image sensor WITHOUT any artificial density / tone added by camera raw?

Thanks,

Alan.

This topic has been closed for replies.
Correct answer elie_dinur

"I'm trying to figure out the best way to get maximum detail without adding any "false" tone in the highlights."

The "best" way is to learn how to expose a Raw file without clipping it although you are exposing as close to clipping as is possible. It's the proper way to get the maximum tonal range and minimum noise from your camera and the best conversion from the Raw Convertor software and it's called ETTR  (Expose To The Right, Google it). Unfortunately it is  a technique has to be learned because cameras don't show you a histogram of the Raw image data but rather of a processed jpg and Lightroom does essentially the same thing, displaying an image and a histogram derived from it that are predictive of what will be exported. Fortunately there are computer applications that will show you the "Raw reality" with a histogram of the Raw and you can learn to correlate between the misleading camera histo and optimum Raw exposure. The two that I use constantly are from the same authors, Fast Raw Viewer and Raw Digger. https://www.fastrawviewer.com/?utm_source=program&utm_medium=site&utm_campaign=FRV

When shooting subjects that require the best possible ETTR exposure, I shoot bracketed triplets +/- a third of a stop, and pick the best ones in FRV before sending them on to LR.

3 replies

elie_dinur
elie_dinurCorrect answer
Participating Frequently
February 21, 2018

"I'm trying to figure out the best way to get maximum detail without adding any "false" tone in the highlights."

The "best" way is to learn how to expose a Raw file without clipping it although you are exposing as close to clipping as is possible. It's the proper way to get the maximum tonal range and minimum noise from your camera and the best conversion from the Raw Convertor software and it's called ETTR  (Expose To The Right, Google it). Unfortunately it is  a technique has to be learned because cameras don't show you a histogram of the Raw image data but rather of a processed jpg and Lightroom does essentially the same thing, displaying an image and a histogram derived from it that are predictive of what will be exported. Fortunately there are computer applications that will show you the "Raw reality" with a histogram of the Raw and you can learn to correlate between the misleading camera histo and optimum Raw exposure. The two that I use constantly are from the same authors, Fast Raw Viewer and Raw Digger. https://www.fastrawviewer.com/?utm_source=program&utm_medium=site&utm_campaign=FRV

When shooting subjects that require the best possible ETTR exposure, I shoot bracketed triplets +/- a third of a stop, and pick the best ones in FRV before sending them on to LR.

S
short73Author
Inspiring
February 22, 2018

Elie,

Thanks.

I'll look into that raw converter; sounds like it could be useful in certain situations as it can show the basic raw with clear indication of where the detail in highlights is lost. (I understand the "ETTR" concept, and as you describe, the issue becomes how much you can go before you blow information out in the highlights, especially because LR will "darken" the pixels in extreme situations so it's difficult to know where the real detail ends...).

Thanks all for the information.

Alan

Per Berntsen
Community Expert
Per BerntsenCommunity Expert
Community Expert
February 20, 2018

As far as I can tell, this is normal behavior.

When there is no detail to recover(i.e. all three channels are completely blown), you get a neutral gray when you drag the Highlights slider to the left,

I'm assuming the camera raw is "adding" neutral density to the highlight area at some point? Where does this "addition" of neutral tone start in camera raw..?

In later process versions, some highlight recovery is done automatically when the image is rendered, but I don't think any recovery is done when there is nothing to recover. So there should not be any neutral tone added automatically.

How do I know when I have the maximum detail from the image sensor WITHOUT any artificial density / tone added by camera raw?

If the histogram has a neutral gray spike bumped up to the right edge (see image below), there is nothing to recover.

If there is some color in that spike, there might be something to recover.

S
short73Author
Inspiring
February 21, 2018

Thanks Per,

I'm still not really sure I understand what's going on because as you say "I don't think any recovery is done when there is nothing to recover. So there should not be any neutral tone added automatically.".....but there is tone added if you move the exposure slider down, getting darker and darker, at a certain point, the highlights (pure white / no detail / nothing) becomes grey. This seems to give the impression that you are actually getting more detail from the file, but that's not the case...it's just getting grey?

Alan.

JohanElzenga
Community Expert
JohanElzengaCommunity Expert
Community Expert
February 21, 2018

Neutral tone is not something that can be 'added'. It's not paint! Each pixel has a value for red, green and blue. If all three values are at maximum (255) the pixel is white. If they are lower, but the same (say 215, 215, 215) then the pixel is neutral grey. That is simply what happens here. The brightness of the pixels is lowered, and so white pixels become grey.

-- Johan W. Elzenga
JohanElzenga
Community Expert
JohanElzengaCommunity Expert
Community Expert
February 20, 2018

It's not a matter of 'adding neutral density', it's a matter of making the pixels darker. When you make an image darker blown highlights will eventually also become darker. But because that won't add any detail, this shows as a solid grey mass of pixels.

-- Johan W. Elzenga
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