loading the histogram to the left

GW
Posted By
greg_wallis
Feb 9, 2004
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On several of my photographs i have experienced small highlights( or large areas of sky) where the colour is completely washed out…..ie just left with white pixels and no way of recovering them.

I stumbled across an article somewhere about always shooting for the left hand side of the histogam……eg ensuring that you have more pixels in the dark areas than in the light areas…..they argued that you can always recover pixels that are abit too dark( contrast masking etc) but once they are white(drastically overexposed) then that information is lost. It took a while for this to sink in but now it makes a lot of sense to me. So now if the animal i am trying to photograph is slightly in the shade,,rather than trying to get the expoosure right on the animal,i should basiclly take my metering from the sky or bright area, and then recover the darkeer dtails of the animal at home on the computer.

No question here…just thought others might be interested or like to comment.!

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CW
Colin_Woodbridge
Feb 9, 2004
Hi Greg….

Interesting concept. I’m not sure I fully appreciate it yet. I would have thought that if you underexpose then there’s an equal possibility of loosing the pixels in the dark.

I do seem to have more burnt out sky’s than pitch black shadows, though.

Any idea of the source material for your interesting topic.

Colin
PD
Pete_D
Feb 9, 2004
My experience has been that you can recover detail from a very dark image, even when there is no detail visible. Washed out light areas do not recover detail well if at all. So I concur with the article.
KL
Kenneth_Liffmann
Feb 9, 2004
My understanding of this is as follows. I may be incorrect, and would welcome correction if needed. The basic principle applies to both film and digital photography. For example, if you point the camera to a beach scene, with a person in the forground and water & sky in the frame, the light meter will read the bright sky and the exposure will be set to this parameter (in "auto"). In order to record details of the person in this example, one should over expose. Exposure compensation is a feature of most cameras. With a digital camera one can bracket the exposure, then toss out the unatisfactory renditions. The beauty of PE is that subsequent corrections can be made additionally.
Ken
CW
Colin_Woodbridge
Feb 9, 2004
Hi Ken…..

I understand the theory of exposure compensation but don’t understand why there should be a better chance of recovering ‘lost’ pixels from shadow as opposed to highlights.

Maybe this is something to do with the sensors. Is it that the CCD/Cmos sensor has less ability to respond to changes in brightness in the highlights than the shadow?

Colin
KL
Kenneth_Liffmann
Feb 9, 2004
Colin,
Richard Lynch in his book, "The Hidden Power of Photoshop Elements 2", addresses aspects of this issue on page 41."Separation for image luminosity is another way to extract valuable tonal information from your image." …"the luminosity component is often a good representation of what we would expect to see in black and white."
Ken
J
john
Feb 9, 2004
I can’t explain it technically from the ‘sensor’ perspective but, yes, it is very much like film negatives IN REVERSE.

On a negative, shadows that are too dark become CLEAR. There is no useful information to be printed from it EVER. At the other end, very bright highlights are ‘almost opaque’. Still, you can sometimes push enough light through when printing to produce detail, although it will suffer from grain, contrast and colour shift (if you’re using colour).

In digital (and also in colour slide film, incidentally), it is the ‘too bright’ highlights that essentially contain no information. Shadow detail can more easily be ‘teased out’.

Many years ago the ZONE SYSTEM was developed by Ansel Adams and has been adopted by many photographers in the decades since. He was using cut-sheet 4 x 5" B & W negative film, of course, and processing each negative separately. Although it’s a gross oversimplification, when faced with a scene that had more contrast than could normally be captured within the tonal range of the film, the idea was to ‘expose to retain the shadow detail’ and ‘process to retain the highlight detail’. This sometimes meant overexposing the shot and underdeveloping by one stop or more.

For digital, many photographers (doing the opposite, of course) will expose to keep the ‘wanted’ highlight detail, and rely on post processing to tease out the shadow detail. You can take this too far, though, and end up with a nightmare post processing job to bring out something important in the shadows.

Many advanced amateur and pro cameras now have the option to display the histogram on the LCD screen after each shot. This is a fantastic boon to the photographer. If you don’t have this capability, then (except for action shots, of course) BRACKET your exposures if you are unsure. With post processing you can even COMBINE two shots to get one that shows detail in both highlights and shadows.
GD
Grant_Dixon
Feb 9, 2004
When you use film the rules are

– expose for the shadows when using print films

– expose for the highlights when using slide films

I’m not how a digital chip works but because there exposure latitude is much closer to slide film I expose for the highlights under normal conditions. That being said it is digital and we should think outside the box and not along film lines of reason. I have seen some very nice work with extreme dynamic ranges when separate exposures were taken for the highlight and the shadows and then combined in Photoshop.

http://www.tawbaware.com/maxlyons/cgi-bin/image.pl?gallery=1

http://luminous-landscape.com/tutorials/blended_exposures.sh tml

http://www.luminous-landscape.com/tutorials/digital-blending .shtml

Grant
DS
Dick_Smith
Feb 9, 2004
Grant, thanks for those links. Very informative.

Dick
SS
Susan_S.
Feb 9, 2004
My take – To get the best out of exposing to push the histogram to the left it is said that you really need to shoot in RAW and then convert using a RAW converter that allows exposure adjustment. I shoot mainly jpg, but I do find that for certain subjects underexposing slightly and then pulling up the shadows works best. My G3 captures an amazing amount of detail in the shadows that Elements can bring up – but no detail at all in overexposed highlights. It’s obviously a technical constraint of the sensors.
So for shots where I want detail in sky and clouds, and so on I will meter carefully and check the histogram after shooting in an attempt to avoid blowing out of highlights (I have my display set so that after each shot it flashes up the histogram and a small thumbail of the image that flashes the blown out areas). For less careful photography outdoors I tend to leave the exposure compensation permanently set on -1/3 to avoid too many problems with overexposure of parts of the image.

The downside of this is that with compact camera size sensors, the bringing up of detail in the shadows increases the noise in these areas of the photographs – I suspect that if I had a RAW converter that allowed exposure adjustment (that works on a Mac, for my camera and didn’t cost an arm and a leg!) and/or a DSLR with a larger less noisy sensor this would be less of an issue.

On the other hand there are some pictures where the blownout sky or whatever is of secondary importance to getting the best possible amount of detail in the key part of the subject – back lit portraits for example – for these I would use the camera’s spot meter setting to meter on the key subject, adjusting the exposure for the amount that the subject is likely to vary from 50 per cent grey….
As Grant says, with wide contrast stationary subjects probably the best bet is to combine images which are exposed for highlights and shadows – I don’t do enough landscape photography where this technique seems to shine to have evaluated it really…

Susan S.
T
Tel
Feb 10, 2004
To add to all the previous comments, I’d agree that overexposed will lose information that cannot be recovered and also that underexposure will increase noise when you bring it up. So underexpose, yes, but as little as possible to retain the shadow detail.

Secondly a tip which I often use on subjects with a high contrast range when the subject doesn’t move about. If you have a histogram function in your camera, use it.
Take two pictures, one exposed for eg the sky and one for the darker parts. A tripod helps for this but you can do it without, then sandwich the two together in PE. It can be a bit tricky at times but it’s worth it. A layer mask, (one of the free hidden power tools) is a great help here.

Tel.
JR
John_R._Collins
Feb 10, 2004
Hi Greg,

My take on this is business is that a washed-out overexposed area containes pixels whose color information is 255,255,255. Darkening these areas results in a shade of gray rather than a color tone. Areas whose pixel readings are 0,0,0 would have to be really dark (black in fact). So, slightly underexposing a digital picture ensures that no pixel ever contains the dreaded 255,255,255 information.
So, when you lighten your picture slightly in PE2, you can make sure that the result never contains washed out areas.

John
CS
Chuck_Snyder
Feb 11, 2004
I’ve set my camera’s exposure compensation at -1/3 stop for all outside sunlight shooting. I get a few very flat (low contrast) shots that I have to spruce up with Levels or Curves, but very few instances of blown-out highlights (usually skies or white buildings).
GW
greg_wallis
Feb 11, 2004
thanks for all the input on this….will now start experimenting with the histogram when i shoot…..never realised that it could play such a crucial role in taking shots.

cheers

greg
JR
John_R._Collins
Feb 11, 2004
Chuck,

With my Oylmpus 2100UZ, I set the outside exposure to -2/3 stop to prevent any washouts in the bring areas. It works well most times for me.

John
CS
Chuck_Snyder
Feb 11, 2004
John, that’s good; I think the point to those who haven’t tried this yet is that a fraction of a stop (-1/3, -1/2, or -2/3) should really do the trick except in the most extreme cases. Of course, if the camera is set to spot metering and you select a deep shadow for the metering point, you’re still gonna be in trouble with the highlights on a very sunny day.

Chuck
LK
Leen_Koper
Feb 11, 2004
Probably the hardest part of learning how to use a camera is how to meter. As soon as you understand the basics you will know which parts of an image are important. Checking the histogram is done after taking the shot just only to check wether you haven’t made a mistake.
Most consumers however buy a camera and rely on auto everything to do the thinking for them. Spending $200 less on the camera and taking a good course for that money will always result in much better images for the same amount of money.
Nothing beats a sound understanding of the principles of metering and controlling your contrasts; don’t worry, there is enough information to be found on the internet and books.
Unlike what camera manufacturers like to make you believe, auto everything just only works for you as soon as you know why the camera does what it does.

I know this might sound rather unfriendly; it isn’t meant to be unfriendly, but metering is such a vital thing that you cannot always do with just only setting the exposure correction at -1/2. Often this will work, but as you all probably will have noticed, your best shots will usually be spoiled by the automatic features of your camera.

Leen
LK
Leen_Koper
Feb 11, 2004
A very good tutorial about metering can be found at:
<http://www.aicite.com/photography/articles/Default.aspx> In the articles about background control and techniques for handheld meters Heinz Richter thoroughly explains the ins and outs of metering.
BTW, this is a very friendly forum -of course nothing beats this forum- with lots of information.

Leen
CS
Chuck_Snyder
Feb 11, 2004
Leen, okay, but…..if I’m in very contrasty conditions and I want a relatively safe starting point to avoid highlights blowout, I’m going to use that -1/3 as the ‘pivot point’ and adjust to either side of it. It seems that both science and experience would drive me in that direction, knowing how easy it is to lose the highlights… Sure, I’ll try to optimize further but you have to start somewhere – and the camera’s ‘neutral’ exposure point doesn’t do it, at least not for my cameras.

Chuck
LK
Leen_Koper
Feb 12, 2004
Chuck, a sound advice: avoid too contrasty conditions. These conditions will never allow you to produce an award winning shot.

This might sound rather blunt, but unfortunately it is true. ;-(

Leen
CS
Chuck_Snyder
Feb 12, 2004
Not wanting to prolong this debate, but…. πŸ™‚

Award winning shots are one thing; life’s special moments are another. The latter may take place in very contrasty conditions, so one must be ready to deal with what nature serves up. I’ve rescued a few high-contrast images with the Contrast Mask technique, although the colors tend to get a little unreal (over-saturated) with that method. And – of course – the mask works a whole lot better when the highlights have been preserved! πŸ™‚

Chuck
BG
Byron Gale
Feb 12, 2004
My digicam (Sony F717) allows me to view the histogram while setting up the shot… Maybe I’ll just enable it, for a while, and see what it tells me.
CS
Chuck_Snyder
Feb 12, 2004
Byron, that’s a really nice feature – I believe I’d use it if I had it, at least in some situations.
GD
Grant_Dixon
Feb 12, 2004
I think Leen is giving good advice. No that is not strong enough, I know Leen is giving great advice. The simple fact is that there is no film, or digital camera that can reproduce the total dynamic range of the eye. This should not be seen as an impediment because this knowledge in the hands of a skilled photographer it is a powerful tool. The meter, in or out of camera, just measures 18% grey. There are no golden rules like 1/3 over or 1/2 under it is all about decisions. If you want to take snapshots use the averaging meter of your camera. If you want to take photographs learn to meter properly.

Grant
CS
Chuck_Snyder
Feb 12, 2004
Grant, we are not all skilled photographers like you and Leen. Those of us who aren’t so skilled need a starting point, and the camera’s average metering is a decent starting point – except when you’re using a digital that blows out easily in high-contrast situations. The recommendation by many writers (including Ben Long, who wrote "Complete Digital Photography", the first book on the subject I bought) is to use as a starting point an exposure compensation of -1/3 to -1/2 stop. I suppose one can eventually learn how to assess the exposure situation either intuitively or analytically and make a more reasoned judgment, but there’s nothing wrong in the early going with giving yourself a better chance of a keeper image by use of a rule of thumb.

If I want to take snapshots – and I take a lot of them – I still want them to have details in the highlights. My camera’s averaging meter with no exposure compensation won’t do that…

Chuck
GD
Grant_Dixon
Feb 12, 2004
Sorry Chuck I don’t buy it. Ben’s arguments are teaching you bad habits. One can only imagine his next book may be called the Complete Digital Exposure Guide. Think about this logically, Nikon and Canon are in the business of selling cameras if they though that this nonsense was true then they would just build it into their cameras to make them look better. Digital cameras have a dynamic range very close to slide film so there is nothing really startling about digital exposure and learning about it is not black magic. You know Leen didn’t fall out of a Christmas tree knowing how to expose his camera he worked at it. With a digital camera and a good book on exposure I suspect you could have 90% of it in about a week or so.

Grant
RS
Robin_Schold
Feb 12, 2004
This thread has been an eye opener for me. I’ve been exposing for the shadow detail and wondering why my highlights are blown. I’ve been shooting as if for negatives instead of slides.
I like the idea of two different exposures combined in extreme ranges. Thanks.

Robin S
LK
Leen_Koper
Feb 12, 2004
Robin, exposing for shadow detail and underexposing by three stops is a B&W technique for measuring. In digital it is often metering for highlights and overexposing two stops.
Best way however is to test the dynamic range of the sensor and measure if your subject falls within this limited range. If not, check which detail might get lost in the shadows without losing much image quality.

Leen
CS
Chuck_Snyder
Feb 12, 2004
Grant, thanks. I’m just going with the percentages on this one, i.e., before I started using exposure compensation, perhaps 50-60% of my outdoor/bright sunlight/deep shadows pictures showed strong evidence of highlight blowout; once I made the switch, the number dropped to 10-20%. Yes, the images shot in this manner exhibit a flatness indicative of underexposure, but that goes away with a quick Levels, Curves or even Auto Contrast adjustment. Perhaps someday I’ll learn how to use the meter properly as you and Leen describe; in the meantime, the rule of thumb works for me and the exposure compensation will remain at -1/3.
GD
Grant_Dixon
Feb 12, 2004
"perhaps 50-60% of my outdoor/bright sunlight/deep shadows pictures showed strong evidence of
highlight blowout;"

Chuck

Oh my god ….. you can get better results from the data that comes with a role of film. Sounds like you have a bad meter.
as you should expect a failure rate of between 5%-10% using and integrated meter.

Grant
SS
Susan_S.
Feb 12, 2004
Grant – while my percentage of blow outs is not quite that high, it’s high – I have long held a suspicion that the exposure meters algorithims are callibrated for the flatter less contrasty tones of Japan and northern european climatic conditions -… the camera algorithms on the more "automatic" "do all the thinking for you’ exposure programs don’t seem to like the summer light in Aus – it’s more than just the contrast is too high – the position of the histogram chosen is half a stop or so further to the right than I would chose in the same conditions…(my winter pictures are much better!). My SLR similarly gives more overexposed shots than I would like – my old Olympus had a much more basic exposure meter which made less assumptions for me about what the pattern of light in a typical image should be, and did a much better job – I shot slides with it too, so it had to be right. I’ve learnt to use the spot meter for more predictable results…Chuck – you probably have similar light where you are to me I would guess. (38ΒΊC today, 43ΒΊC and a strong north (straight from the desert) wind tomorrow ..)

Susan S.
LK
Leen_Koper
Feb 12, 2004
Susan, Chuck and anyone else with a success rate below 90%. You are right for quick snaps to use the -1/2 stop underexposure.
However, as soon as you have time, switch to a more successful way of metering in contrasty situations like in full sun.(I always try to avoid full sunlight as it is the worst way of lighting that exists)
As most digital cameras have spot metering, use this feature and measure the brightest highlight where you need to see details. Overexpose this part of your image by about 1 1/2 stop. The shadows will take care of themselves.
Before doing so, check the exposure latitude of your camera by means of shooting pages of a newspaper (almost similar to neutral grey) and bracket with small increments for overexposure. As long as you see details in the printed pages, you will know that at this overexposure your highlights will not be blown out. That is the maximum overexposure you can use for your highlights.
Working this way seems to be pretty complicated, but as soon as you get used to it, you can work pretty fast and carefully at the same time and your success rate will be close to 95-98 %

Leen
CS
Chuck_Snyder
Feb 12, 2004
Leen, thanks. That’s a keeper tip! Now if I can only figure out the various buttons to push in what sequence to record an exposure value in one part of the image while setting the focus point in another part of the image…I believe I need a third hand to do this on one of my cameras… πŸ™‚

p.s I hadn’t thought of a newspaper as approaching neutral gray; I guess you’re saying the combination of the offwhite paper and the black print is seen by the meter as neutral gray….?
SS
Susan_S.
Feb 12, 2004
If I’ve got time I use the spot meter – it’s much more predictable then letting the camera evaluative metering algorithms do the calculations – the newspaper trick is a good one, Leen. The only thing I have to be a little bit careful about is if I’m using flash – the Canon e-TTL flash exposure is calculated by the pre-flash at the moment of firing the flash – so if I set the exposure using the spot meter by moving the camera to get the subject on centre and holding the shutter button half way and then recomposing, (which is what I do with my non- e-TTL SLR), when the flash sets its exposure then the meter point will no longer be looking at the object – which gives the potential for some inaccurate exposures…you need to either use the flash exposure lock (which fires the preflash) and then recompose, or move the AF point around the frame to the subject to calculate the exposure… the latter is a very useul feature of the G3 which I often forget that I have….
Susan S.
LK
Leen_Koper
Feb 12, 2004
About the newspaper, this comes pretty close to neutral grey.

About a third hand, we usually call this a tripod. πŸ˜‰
When shooting in similar situations and the lighting doesnot change, you often can apply the same correction you have measured before.

Pretty often it is the easies way to shoot with aperture priority instead of full auto. This way you can controll your depth of field too.

Leen
J
john
Feb 13, 2004
Here are a couple of pages that talk about a simplified zone system of metering. They focus on negative film, but have tips on slide film and some info about shooting digital (which is more like shooting slide film than negative film). They might help clarify why Leen would suggest, for example, to meter for the important highlights and overexpose from that reading by about 1.5 stops. In the ZONE system, this is equivalent to putting your highlights in between zone VI and zone VII Β– well within the range of most slide films and digital cameras.

<http://www.apogeephoto.com/mag2-6/mag2-7rh.shtml> <http://www.normankoren.com/zonesystem.html>
GD
Grant_Dixon
Feb 13, 2004
For those that don’t want to carry a grey card or want to buy an incident meter I would like to point out a very inexpensive add-on to photographic metering. Your hand! The average person’s hand (Caucasian) is on stop brighter than an 18% grey card so meter of your hand and close down one stop for a accurate 18% metering. Remember to make sure your hand is light in the same fashion as the object you want to photograph

Grant
LK
Leen_Koper
Feb 13, 2004
Now you know why your mother always insisted on: "And don’t forget to wash your hands!"

Leen

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