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Thread: Saving the Whites; When and How!

  1. #1
    Ken Watkins
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    Default Saving the Whites; When and How!

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    Thanks to Ken for posting this image. I wrote a short tutorial below as folks are just not getting the concepts outlined below...

    artie

    Taken on Mapula Concession Botswana 15th September 2008

    Canon EOS 1d MkIII

    500mm IS hand held

    F6.3, 1/2000, ISO 500

  2. #2
    Publisher Arthur Morris's Avatar
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    Please note: I revised this on 10/20/09.

    Hi Ken, Lots of important lessons here. I brought the image into PS to reduce the contrast (which I did) and noted that as presented originally above, there were lots of overexposed pixels, not only in the whites of the neck but in the reds and the yellows. I reduced the red and yellow SAT and eliminated the over-EXP in those areas, but the whites are un-salvageable at this point.

    I see this in many images here so I came up with this tutorial:

    #1: The best time to "save the highlights" is at the time of capture. After making a single image of a subject in a given light, you need to check both the histogram (to make sure that you are exposing well to the right), and then check for flashing highlights (or visa versa). If you have any flashing highlights, you need to subtract light from your exposure.

    #2: If you do wind up with some over-exposed pixels, they must be dealt with during conversion! If you convert the image too light, i.e., with over-exposed pixels, then you can never recover the highlights... Most every program used to convert our images has a way to a-check for over-exposed pixels--you need to have the alerts set in whatever program you are using. In ACR, set up the red warning for overexposed highlights and the blue warning for underexposed shadows. I believe that it is pretty much the same in Lightroom and Aperture. It is possible to both check for and recover flashing highlights in Aperture.

    In Breezebrowser, I simply hit Exposure Compensation in the Conversion Window and then check the histogram. If the image shows clipped highlights, I reduce the EXP and then use Combined as the conversion. This helps recover apparently but not actually lost highlights.

    In ACR, your first move with all images should be with the Recovery Slider (even if you do not see any red warnings). Hold down the ALT key; if there are no warning pixels showing, leave the Recovery Slider as is and move on to the Exposure Slider. (See the instructions below for the Exposure Slider.)

    It you see warning pixels while holding down the ALT key, move the Recovery Slider to the right until the warnings disappear. If and when they all disappear, leave the Slider where it is. No need then to go on to the Exposure Slider. Just move on to the Black Slider.

    Whenever you move the Exposure Slider, hold down the ALT key just as you did with the Recovery Slider. If there are no hot pixels showing, move the slider to the right until you see a few pixels and then back off till they disappear. If you are still seeing hot pixels after moving the Recovery Slider to 100, move the EXP Slider to the left...

    With badly overexposed images you might not be able to save the highlights or if you do, the overall image may become well underexposed. Next time get it right in the field!

    #3: If you have whites that are technically not over-exposed but lack density and detail, you can improve those areas by either Multiplying the selection or applying a Linear Burn. See that thread in Education Resources.
    Last edited by Arthur Morris; 10-20-2009 at 07:11 PM. Reason: Change in Workflow Techniques
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  3. #3
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    Art,

    I agree with everything you said. excellent advice.

    I'll add some ideas for those problem images. Like the image that is posted at the beginning of this thread, it has some saturated portions. Some things that can help recover detail:

    In the conversion, use 16-bits per pixel. The increased intensity detail may allow you to bring out subtle differences between pixels that aren't quite saturated.

    Do a linear raw conversion with no white balance. This is a raw conversion only with Bayer interpolation. Most raw converters do not have this option. I use ImagesPlus and DCRAW. DCRAW is free (you can get the source code too). With this type of conversion, if one channel is not saturated, you can use it to recover detail. For example, often the blue channel us not saturated because digital sensors are less sensitive to blue light. Extract the blue channel, convert to black and white and use it as a layer to modulate the main image, for example using Art's idea of linear burn.

    When colors appear blocked up. convert to CMYK space and work on the color OPPOSITE that blocked up. For example, if the yellows appear blocked up, work on the yellow area in the cyan channel. E.g., seclect the area and use curves to put detail in the cyan channel.

    If only a few fine details are saturated, e.g. back-lit hair is saturated, so only a few pixels wide: try a little blur. The blurring averages the pixels, and can unsaturate them. You can then resharpen.

    Roger

  4. #4
    Samir Begovic
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    Guys, I think you forgot to mention white balance. It is often very important factor in determining a look of the histogram. You can check it by playing with WB and looking what happens to the histogram. It may not always be a big difference, but when we work on shot of snowy egret on a bright sunny day, every bit of shade may be important.
    Roger,
    you are right that we can easier do some moves by converting to CMYK, but only as last conversion and if we actually wanted to output CMYK. You probably know that we loose a lot of information in that conversion and converting back to Lab or RGB doesn't bring it back. The only "safe" conversion is RGB to Lab an the other way.

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    Quote Originally Posted by Samir Begovic View Post
    Roger,
    you are right that we can easier do some moves by converting to CMYK, but only as last conversion and if we actually wanted to output CMYK. You probably know that we loose a lot of information in that conversion and converting back to Lab or RGB doesn't bring it back. The only "safe" conversion is RGB to Lab an the other way.
    I disagree. There is no loss when converting LAB or RGB to CMYK. There can be small losses in shadow detail in going back, but that is easily compensated for by working in 16-bit or higher.

    See: Photoshop Professional, The Classic Guide to Color Correction, by Dan Margulis, John Wiley and Sons, New York, 2001 (there may be a newer version, but this one has plenty of info).

    I have corrected blown reds, especially in Fujichrome Velvia drum scans by converting to CMYK and working on the cyan channel, for example, and then converting back to RGB. This image is an example:
    http://www.clarkvision.com/galleries...e_taryall.html
    The enlargement below the main image was a red blob before correction (as were some other red flowers) before the CMYK correction. And the image makes stunning 30x40 inch prints (which have been on display in multiple galleries).

    Roger

  6. #6
    Samir Begovic
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    You can check the file size after reconversion. It becomes smaller. Now, there are situations where is well worth make that sacrifice, like in your example where it worked wonderfully.

  7. #7
    Samir Begovic
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    Maybe we don't talk about the same thing. This is what I meant: left original. right reconvert. Made as new 16 bit images.This time however, reconverted image is 0.001 MB smaller. :o


  8. #8
    Samir Begovic
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    Quote Originally Posted by Samir Begovic View Post
    ...This time however, reconverted image is 0.001 MB smaller. :o
    ...
    I meant the original is smaller (sorry).

  9. #9
    Robert Amoruso
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    Two points to clarify some things mentioned above.

    LR has similar features in the developer module that you find in ACR in Photoshop such as recovery, fill light, blacks and exposure.

    Breeze browser Pro can do linear conversions.

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    Visited this thread for the first time after receiving the "Letter from Artie". I am relatively new to all of this, do not use Photoshop, and was wondering if Scott Bourne ever commented on highlight recovery in Aperture?

  11. #11
    vbpholaw
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    I too took a look at this thread after receiving Artie's letter. Obviously, he intended that when he wrote the letter, so hopefully there will be some follow-up. One thing I noted in Artie's original text post was the following:

    "In ACR, you first reduce the EXP and then use the Recover slider until the red warning disappears. You should almost always use the Recovery slider before you use the Exposure slider."

    There is a conflict here between the first and second sentences. The question is which one Artie meant.

    From my experience with Lightroom (essentially the same RAW converter as ACR), I will usually use the exposure slider to eliminate, or come close to eliminating the red warning if a significant portion of the image needs exposure reduction (e.g., an "exposure to the right"). However, if the majority of the image is properly exposed, I may use only the recovery slider to bring down the highlights (as it will have far less impact on the rest of the image), or I will use a selective exposure adjustment using the adjustment brush (to avoid any impact on any other area of the image). Sometimes there may be a combination of all of these, depending on the original. The general principle, I think, is that there are various options that the photographer should try to get the best results possible, and that there is not a "one size fits all" type of adjustment or processing that should be used.

    I would add that a saddle bill stork (which I think is the bird in the original posted photo), in bright front lighting, probably presents as harsh a contrast/exposure situation as you can find in nature, with both white and black, as well as primary colors (red and yellow) that could oversaturate (particularly if the stork has been fishing and its beak and head are wet, adding to their reflectivity).

  12. #12
    Lifetime Member Jay Gould's Avatar
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    #2: If you do wind up with some over-exposed pixels, they must be dealt with during conversion! If you convert the image too light, i.e., with over-exposed pixels, then you can never recover the highlights... Every program used to convert our images has a way to a-check for over-exposed pixels--you need to have the alerts set in whatever program you are using. In ACR, set up the red warning for overexposed highlights and the blue warning for underexposed shadows. I believe that it is pretty much the same in Lightroom and Aperture. One I get back on line I will have Scott Bourne comment here on Aperture. It is possible to both check for and recover flashing highlights in Aperture.
    LR has similar features in the developer module that you find in ACR in Photoshop such as recovery, fill light, blacks and exposure.
    I have not used ACR; currently I use LR and I am considering BB as a step before LR.

    However, perhaps I am having a problem in the workflow time-line understanding "when" Artie is referring to "conversion": "If you do wind up with some over-exposed pixels, they must be dealt with during conversion!"

    In LR, we use the developer module after we have imported the CR2 files into LR.

    Is "conversion" being used synonymously with PP prior to converting to a jpeg, tiff, or psd?

    Cheers, Jay
    Cheers, Jay

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