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What causes this 'milkyness' in shots with added brightness

Discussion in 'Olympus Cameras' started by ardy, Jan 2, 2016.

  1. ardy

    ardy Mu-43 Rookie

    19
    Aug 18, 2013
    Hi All,

    I use a OMD EM5 and previously an E-520

    I do some underwater photography and I can easily get under exposed shots (flash not fully charged, fstop too high etc etc.)

    I do all my U/W photography in manual.

    When adjusting my shots in irfanview, if I adjust the brightness there is what I am calling a 'milkiness' that appears in the shots. I have used P/S as well and notice the same thing.

    Anyone know what causes this is and how to avoid/fix it?

    This photo I have adjusted to make it 'milky'
     

    Attached Files:

  2. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    You say you "adjust the brightness". Are the shots underexposed? What that looks like to me is a shot of a scene with a limited brightness range that has been underexposed so "brightening" it enough to get the bulk of the image looking right results in the darkest tones being too light plus no really bright highlight areas as well. You could start by increasing the contrast, perhaps raising the white point and lowering the black point also, or raising the brightest highlights a bit and lowering the darkest shadows a bit with a curves adjustment. In addition the water may not be entirely clear and whatever is in the water could be scattering the light a bit and contributing to the "milkiness". If your software has a "dehire" control that may help, otherwise a midrange contrast control labelled something like "clarity" or "definition" may help. I'm not familiar with irfanview so I can't make specific suggestions for it.

    I'd also look at giving a bit more exposure in camera when shooting.

    Same photo played with in Lightroom.

    94356-bae0715314a6d062d9e2869dee0caf12.

    I reduced the brightness/decreased exposure, reduced the highlights and white point, darkened shadows and lowered the black point, increased contrast and increased clarity. It still looks a little "hazy" which could be the water.

    The histogram for the image as you posted it was all pushed to the right with nothing in the shadows and nothing pushed up against the right edge of the histogram. That indicates a low contrast scene and given your comment about having adjusted the image to make it milky I suspect it was quite underexposed and you brightened it quite a bit, all of which supports my suppositions above.

    Start with more exposure in camera so you don't have to brighten the image as much and work on increasing contrast in the image because you're probably going to be confronted with a lot of low contrast scenes underwater because of the way water absorbs light.
     
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  3. ardy

    ardy Mu-43 Rookie

    19
    Aug 18, 2013
    Thanks David - this shot in RAW is OK and the water vis. was about 20m. I just increased the brightness on this shot to show what I mean.

    This ONLY happens after they have been processed and the 'milkyness' is generally NOT in the RAW image. It is only when I try to drag back an under-exposed image that I get this effect. Often they are shots I would like to keep.

    I will try your idea of reduced highlights etc.

    There are problems with ensuring correct exposure that do not exist on land where the closest is probaly bird photography. Underwater photography issues inc. moving life and controlling your buoyancy, whilst ensuring correct exposure, background + focus and everything can change in parts of a second. The effectiveness of the dual flash system I use drops off dramatically after about 1.5m, so you can be forced to grab an under exposed shot sometimes. Hell! I, like many others, can stuff up a shot from 300mm away.

    I hope there is a process to fix this but I am not hopeful as I have lived with it for the last 8 years of digital photography.
     
  4. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    Looking at the histogram of the image, I think the big problem is that the dynamic range of the scene is not large, probably only about half of what the sensor can capture. In that kind of situation you want to avoid underexposure at all costs, you really need to "expose to the right" because you'll make best use of the sensor's capabilities that way. Just don't clip any highlights where you want to keep detail and judging from the range of that image you'll want to keep all of the highlight detail there is.

    Exposing to the right is going to mean overexposing the image in terms of what the meter is going to recommend. You're going to have to compensate for that by reducing brightness in processing, and then work at building contrast because there's not enough range between the highlights and the shadows in a low contrast scene. Because of the low contrast/limited brightness range of the scene there's going to be a tendency for all of your images to have this problem so spend a bit of time running some test shots, bracketing exposures, and learning how to expose for best results. I'm happy to accept your comment that there are problems with ensuring correct exposure which do not exist on land but you do need to work out what kind of exposure approach gives you best results and the only way to do that is by running your own quick and dirty tests in order to find out what works, If you discover that you really need to give 1 stops or 2 stops extra exposure as a matter of course, then dial in that much exposure compensation and then rely on the meter. The exposure compensation setting will deliver the right result, or at least a better result, then. You should expect to have to routinely increase contrast with this sort of image no matter what you do in camera because part of the problem is the brightness range of the scene and you're limited in what you can do about that. More exposure will help and after that it's a matter of learning how to process low contrast images for best results. That's the only process to fix it that I can think of.
     
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  5. Clint

    Clint Mu-43 All-Pro

    Apr 22, 2013
    San Diego area, CA
    Clint
    The only way I can get a similar result is to move the black point. When doing no more than reset the black point, this is the result -
    Untitled-1.
     
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  6. Jfrader

    Jfrader Guest

    You are trying to adjust the dynamic range by moving only the brightness and as a result "washing out" the image. Instead of moving brightness, try opening the "Levels" adjustment and moving both ends in to where they just touch the histogram. Clint did something like that above using black point and improved the image 100%. You can adjust the black point, white point, or grey point in "Levels" or adjust the "Curves" but that may require a better program than IRfanview.

    Here is my attempt, using basic FastStone Levels and Curves. Took about 10 seconds.

    fish-test.
     
    Last edited by a moderator: Jan 3, 2016
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  7. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    Yes, that's a better approach. I just tried resetting the image to where it was as posted and just lowered the black point until I got clipping and got a very similar result with just one adjustment.
     
  8. ardy

    ardy Mu-43 Rookie

    19
    Aug 18, 2013
    Thanks David, To realise that only half of the sensor is being used is a bit of a surprise.
    I have set my camera up to over expose 1/3 of a stop on flash but if there is insufficient light - well there is little you can do. Many U/W photographers, amateurs like myself, get a fair number of underexposed shots. I use twin Sea n Sea flashes and they are both near top of the range in terms of output and I fire both in manual mode.

    Is there a name for this effect? Do you or any of the other photographers here get this 'milkyness' on their shots?
     
  9. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    You are using all of the sensor, not half of it. What's going on is that the difference in brightness between the brightest part of the image and the darkest part of the image is only about half of the range that the sensor can accommodate. The reason for that is that the water is absorbing a lot of light and the range of brightness from light to dark you get underwater is less than it is above water. That's normal, and the sensor is recording the full range of brightness that's there. Part of the problem is that sensors can only record brightness but your eye doesn't act that way, you've got this funny image processing computer called a brain hooked up to your eyes and it does all sorts of things behind the scenes that you aren't consciously aware of, like scanning from dark areas to light areas and doing a bit of HDR for you in the background so you "see" a more contrasty scene than is actually there. The camera captures the lower contrast range which is actually there.

    What you have to do to compensate for that is to increase the contrast of the image and that can only be done in processing. There's no camera setting that will do that for a RAW image. You can do that by moving the contrast slider, or by increasing highlights or exposure and then darkening shadows. The best way to go about increasing contrast depends on how much contrast there is in the image before you start work on it and also on whether it's underexposed, overexposed, or reasonably well exposed. Because of the way sensors work, when you have a scene which has a much smaller brightness range than the range your sensor can capture, as is the case in this photo, you're better off increasing exposure to just short of the point where you start to get highlight clipping (moving the right edge of the histogram just short of the right edge of the histogram display area) because that means you'll get more detail and better gradation in the image, and it will also keep noise to a minimum, but it also means that the first thing you do when you start processing the image is to either reduce the exposure setting or just pull the shadows down really hard. You'll have to work with all of the exposure/contrast/highlights/shadows/whites/blacks sliders, the ones which control exposure in various parts of the image, in order to get that best result, but you'll be starting off with what looks like an overexposed photo rather than what you started with on this one which was an underexposed photo. The outcome will be a better result but you have to learn just how far you can go in increasing exposure without clipping highlights and that's going to depend on water conditions, your depth which affects light absorption, and also on the characteristics of your particular camera model and its sensor. Sorry but there's going to be a bit of "suck it and see" work involved in order to get a feel for it. What I'd suggest doing is starting off with whatever exposure you normally use then take several more shots increasing the exposure each time by a stop or half stop up to around 3 or 4 stops extra exposure and you'll soon learn how far you can go. Don't worry if the fish moves, keep photographing the same area. Use the first shot for whatever photo you want to get and use the others to work out when things start to clip. If you get a good image in one of the shots with more exposure and you don't have clipping in it, then that's a bonus while you're running these exposure experiments.

    I don't think there's a name for the effect but it's just the way low contrast images work when you don't have any highlights that go close to the top of the brightness range and no deep shadows that go anywhere near close to black. Things look washed out because there's simply nothing really bright or dark in the image. You don't have to get the full range from pure white to pure black in the image, and sometimes you want a really low contrast image such as if you're photographing people in fog where everything is just shades of mid-grey, but in order to bring out the colours of things like that fish in your photo you do need to have the photo have a bigger difference between brightest and darkest areas than was actually present underwater and you can only do that by increasing contrast during processing.
     
  10. PacNWMike

    PacNWMike Mu-43 Hall of Famer

    Dec 5, 2014
    Salish Sea
    guess?
    About the same result with FS Auto-adjust color. 1/10 sec. :) You sure get a lot of bang for your buck with FS.
     
  11. kevinparis

    kevinparis Cantankerous Scotsman

    Feb 12, 2010
    Gent, Belgium
    Beware of what controls in your image processor of choice actually do... a slider marked brightness in one app doesn't do the same in another app

    Many years ago when I taught photoshop, touching the brightness slider was a no no... because it basically just shifted all values equally to the right.

    In Aperture.. my tool of choice, Exposure and Brightness do different things and live together in a panel that also sets black point and recovery... you do have to learn to read the histogram to work out what is going on.

    If you are shooting RAW you have amazing control if you know what your are doing... eg understanding the histogram

    K
     
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  12. Clint

    Clint Mu-43 All-Pro

    Apr 22, 2013
    San Diego area, CA
    Clint
    @ardy@ardy, I don't think there is anything significantly with your camera now use of flash. Even if your shots were 3-4 stops underexposed you should not get the reduced constant result you are getting. I'm not sure Ifranview has a reset, but if it did I would reset and try again. If no reset then I'd uninstall and reinstall. And I'd try one of the other RAW tools out there.

    As @kevinparis@kevinparis said, not all software adjustments work the same even though they are named the same. And I believe you issue lies with software.