Skip to main content
This topic has been closed for replies.
Correct answer Jao vdL

Underexposed images are far more likely to be recoverable than overexposed ones. You just get a bit more noise. With sensors from the last several generations this is actually really minor and images that are underexposed by two or even more stops are easily rescuable in post. They will look absolutely identical to the same images just taken at two stops higher ISO. Rarely a problem nowadays. In overexposed images you run a great risk of losing all detail in the highlights. In this way digital capture works differently than film capture which had a soft "rolloff" in the highlights. Digital sensors just cap when they are saturated and information is lost. Some software such as Lightroom employs algorithms to try and recover the highlights but this is very limited and only works when at least one of the color channels is not clipped. Of course if the highlights are OK clipped a bit such as an image taken straight into the sun where that area is just white, that might not be a problem. If it is a white dress where you want to see the texture it would be a real problem and you really want to make sure it is not blown out. Highlight recovery will in general not bring it back except if it is really on the border of clipping.

Bottom line: expose so that the brightest areas that you want detail in are just below blown out. Note that the highlight blinkies on most cameras trigger earlier than the real sensor clipping occurs and most of the time the histogram on camera backs clips on the right side earlier than the actual raw data does. You usually have a bit of headroom assuming you shoot raw. The camera-back histogram and the blinkies are based on the in-camera generated JPEG not on the raw data. A little blinking is not a problem. If large areas are blinking, you will not be able to recover those.

7 replies

alireza852019
alireza852019Author
Participating Frequently
March 31, 2019

Wowww! too many replies on my question. I'll read'em & answer those & pick the best & right answer asap!.

Thank you all.

Alireza

D Fosse
Community Expert
D FosseCommunity Expert
Community Expert
March 31, 2019

alireza852019  wrote

Wowww! too many replies on my question.

Too many? Not at all. Rarely have I seen a question so completely answered, all of it right on target. This is one of those few cases where I need to bookmark a thread for future reference, and so should you Excellent stuff, thanks everybody.

    Bob Somrak
    Bob Somrak
    Legend
    March 28, 2019

    alireza852019  wrote

    Hi...

    Which photo has the chance to be recovered more successfully? An "over-exposed" photo or an "under-exposed" one?

    Thanks

    Getting back to the OP's original question, I think they need to define HOW MUCH over or underexposed they are talking about.  If it has blown highlights (that are unintentional) than it is a throw away unless you are willing to do some repair in Photoshop.  If it is extremely underexposed than how much noise and other issues are you willing to accept. I for one don't like blown highlights

    M4 Pro Mac Mini. 48GB
    TheDigitalDog
    TheDigitalDog
    Inspiring
    March 28, 2019

    https://forums.adobe.com/people/Bob+Somrak  wrote

    alireza852019   wrote

    Hi...

    Which photo has the chance to be recovered more successfully? An "over-exposed" photo or an "under-exposed" one?

    Thanks

    Getting back to the OP's original question, I think they need to define HOW MUCH over or underexposed they are talking about.  If it has blown highlights (that are unintentional) than it is a throw away unless you are willing to do some repair in Photoshop.  If it is extremely underexposed than how much noise and other issues are you willing to accept. I for one don't like blown highlights

    Outlined above but again:

    https://www.fastrawviewer.com/blog/in-camera-histogram-doesn%27t-represent-exposure

    http://digitaldog.net/files/ExposeForRaw.pdf

    https://www.fastrawviewer.com/blog/spot-meter-exposure

    https://www.rawdigger.com/howtouse/exposure-for-raw-or-for-jpegs

    Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"
    TheDigitalDog
    TheDigitalDog
    Inspiring
    March 28, 2019
    1. Exposure only takes place at time of capture. Despite the name of controls in software (Exposure), you can't alter exposure after capture. Exposure is the attribute of how much light strikes the sensor and thus, ONLY shutter and aperture. NOT ISO! That simply affects the meter which can often lie.
    2. You can't gauge ideal exposure of raw using any of LR's tools; it has no raw Histogram. You need a raw Histogram to understand the actual effect of exposure on the data, hence a product like RawDigger.
    3. Ideal exposure is somewhat subjective but that usually means, NOT clipping highlights where you want detail. You may very well wish to clip specular highlights, you may not. But the only way to determine this is to examine the raw data, NOT a rendering in a raw converter.
    4. IF you actual over expose highlight data you didn't want to clip, nothing will bring it back. So in that respect, slight under exposure would be more ideal; you didn't clip that highlight data you didn't wish to clip. But under exposure produces more noise in the capture.

    ETTR is an old and kind of bogus term that needs to go away. EOFR (Expose Optimally For Raw) is more appropriate. Exposure is photography 101, no matter if the exposure is a raw, a JPEG, a transparency or a neg. You're not (shouldn't) be using the wrong tool ( a JPEG Histogram) to optimally expose raw then moving 'to the right'. Many of us old timers, shooting transparency film (professionally no less) that had little if any latitude for incorrect exposure ever had or needed an LCD or a Histogram to produce optimal exposure. Neither does anyone else really. The key is understanding how meters can be fooled and when, and how to treat the conditions of the media (again, film or digital; JPEG or raw) along with the behavior of the meter recommendation.

    Some areas to read up on in terms of optimal exposure of raw:

    https://www.fastrawviewer.com/blog/in-camera-histogram-doesn%27t-represent-exposure

    http://digitaldog.net/files/ExposeForRaw.pdf

    https://www.fastrawviewer.com/blog/spot-meter-exposure

    https://www.rawdigger.com/howtouse/exposure-for-raw-or-for-jpegs 

    Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"
      J
      Community Expert
      Jao vdLCommunity Expert
      Community Expert
      March 28, 2019

      Thanks for great info everybody. Probably more than was asked for.

      Completely agree with digitaldog that ETTR needs to go away in favor of

      expose optimally. What has always bothered me is that the explanation

      behind ETTR was always based on bogus physics and a misunderstanding of how

      light detection in these sensors works. The argument of bits per stop was

      always wrong as all that matters is that the size of the bitstep is smaller

      than the noise at the light intensity the pixel is detecting. This is

      always true with current sensors.

      On Thu, Mar 28, 2019 at 12:43 PM thedigitaldog <forums_noreply@adobe.com>

        TheDigitalDog
        TheDigitalDog
        Inspiring
        March 28, 2019

        Rawdigger and such are fine but these are tools to analyze the photo once it is downloaded from the camera.  They don't do too much good when you are out in the field pushing the shutter button on the camera.  Using these tools to "calibrate" your exposure methods to try to eke the last 1/3 stop of exposure latitude of the sensor is a recipe for a lot of photos with unrecoverable highlights.  I prefer a "little" headroom  to prevent blown highlights and having an acceptable photo instead of a throw away. 


        https://forums.adobe.com/people/Bob+Somrak  wrote

        Rawdigger and such are fine but these are tools to analyze the photo once it is downloaded from the camera.  They don't do too much good when you are out in the field pushing the shutter button on the camera. 

        Because such tools are not necessary in the field. Never were. Not when some of us shooting professionally, on transparency film, that required nailing exposure within 1/3 stop did so every day. It's these new digital shooters who can't figure out how to expose without Histograms (worse, those that lie) or LCDs that struggle with exposure. You only need to use these tools to understand how your sensor responds to exposure with your various meters and understand how and when meters lie. It's been done for like 100 years this way Bob. It's hardly rocket science.

        Author “Color Management for Photographers" &amp; "Photoshop CC Color Management/pluralsight"
          Conrad_C
          Community Expert
          Conrad_CCommunity Expert
          Community Expert
          March 28, 2019

          The answer to this used to be very simple: Adding exposure only helps the image, as long as important highlights aren't clipped.

          It's a little more complicated now, with the rise of ISO invariant sensors. Today, depending on your camera, it might be OK to keep the camera at its sensor's base ISO, not be concerned about filling the right end of the histogram, and boost the Exposure in Lightroom. Whether you can use this method depends on whether your camera's sensor is ISO invariant. If it isn't, ETTR would produce an image with less noise.

          The following link explains it further:

          ETTR, ETTL and ISO Invariance: Which is Right for You?

            Todd Shaner
            Todd Shaner
            Legend
            March 28, 2019

            Adding on to Jao vdL excellent advice. Overexposed image files that have fully clipped highlights (R,G,G2,B at maximum level) are NOT recoverable and will have no image detail in those areas. If only one or two channels are clipped LR's Exposure and Highlights controls can partially recover image detail with some color mismatch compared to the surrounding non-clipped area. Whether or not that's an issue is dependent on WHAT is clipped. If it's just bright reflections on metallic and glass surfaces or solid white areas that have no detail then it's usually not an issue.

            Underexposed images are fully-recoverable by simply raising the LR Exposure control setting. However, each +1.0 EV Exposure setting increase is the equivalent of raising the camera's ISO setting by a factor of 2x. This increases shadow noise in the image by an amount dependent on the actual camera ISO setting and its sensor noise performance. When shooting at a low ISO setting (100) most cameras maintain good image quality with 1.0 EV underexposure. You may need to add a small amount of Luminance NR and/or adjust Sharpening, but the image quality should still be good.

            The problem is that there is no way to determine actual raw file data clipping inside LR. It requires using an external application such as RawDigger, which allows measuring the actual raw file data to determine what pixels are overexposed or underexposed. To determine how your camera's exposure metering behaves try shooting with it set for auto exposure bracketing using -.66 and +.66 offset. Download a trial copy of RawDigger and then check the images for 'Overexposure.' Based on a sampling of subjects and lighting conditions you'll better understand when you need to add manual exposure correction and in what direction. When evaluating image files with RawDigger keep in mind what I said above. Bright reflections on metallic and glass surfaces or solid white areas that have no detail are usually not an issue. If those are the only overexposed areas in the RawDigger image the exposure is OK.

            J
            Community Expert
            Jao vdLCommunity ExpertCorrect answer
            Community Expert
            March 28, 2019

            Underexposed images are far more likely to be recoverable than overexposed ones. You just get a bit more noise. With sensors from the last several generations this is actually really minor and images that are underexposed by two or even more stops are easily rescuable in post. They will look absolutely identical to the same images just taken at two stops higher ISO. Rarely a problem nowadays. In overexposed images you run a great risk of losing all detail in the highlights. In this way digital capture works differently than film capture which had a soft "rolloff" in the highlights. Digital sensors just cap when they are saturated and information is lost. Some software such as Lightroom employs algorithms to try and recover the highlights but this is very limited and only works when at least one of the color channels is not clipped. Of course if the highlights are OK clipped a bit such as an image taken straight into the sun where that area is just white, that might not be a problem. If it is a white dress where you want to see the texture it would be a real problem and you really want to make sure it is not blown out. Highlight recovery will in general not bring it back except if it is really on the border of clipping.

            Bottom line: expose so that the brightest areas that you want detail in are just below blown out. Note that the highlight blinkies on most cameras trigger earlier than the real sensor clipping occurs and most of the time the histogram on camera backs clips on the right side earlier than the actual raw data does. You usually have a bit of headroom assuming you shoot raw. The camera-back histogram and the blinkies are based on the in-camera generated JPEG not on the raw data. A little blinking is not a problem. If large areas are blinking, you will not be able to recover those.

            Bob Somrak
            Bob Somrak
            Legend
            March 28, 2019

            In general, clipped shadows are less of a problem for the aesthetics of a photo than blown highlights.  I haven't seen too many photos where blown highlights are acceptable and the ones where it is acceptable were planned to be that way.  In situations where the light and subject are consistent and there is no time constraint you can analyze your histogram and do ETTR but for subjects in changing light and subject conditions where you don't have a second chance to take another photo (during a wedding for instance) I would give headroom in the highlights so there is no chance of blowing them out and let the shadows clip.  How you expose needs to be determined for each subject.

            M4 Pro Mac Mini. 48GB
            dj_paige
            dj_paige
            Legend
            March 28, 2019

            The expose to the right technique indicates that you will get better recovery from an overexposed image (as long as it is not too severely overexposed).

            But the great thing about Lightroom is that you can try it yourself and see which one you like better.

            Conrad_C
            Community Expert
            Conrad_CCommunity Expert
            Community Expert
            March 28, 2019

            Just adding that, thanks to ETTR, some say that even a very bright camera raw image is technically not "overexposed" unless important highlights are clipped. It's actually higher quality, less noisy data.

            Terms & ConditionsAccessibility statement
            Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices