Recovering highlights

[Stephen]

Have you ever noticed how when photographing certain things, unless you underexpose by a considerable amount its not easy to avoid blown highlights.

Swans are one such thing that you can have great difficulty with, and its usually the case that there are some blown highlights somewhere in the swans plumage.

Adobe Lightroom seems to have made recovering such highlights much easier. The exposure tools especially the Recovery tool make it a breeze and just to help you a little more you can switch on the highlight indicator and see them disappear as you move the slider.

Here's a shot taken recently of a swan where the blown highlights have been recovered. Lightroom really is one cool program.

[bigbob]

Re: Recovering highlights

Tend to agree up to a point Stephen but we both know that blown highlights contain no detail at all and cannot be recovered , so what you're recovering are semi-blown highlights
No program in the world will recover totally blown highlights , thats why i think you're thread title is a little misleading .
Lightroom is a really good program , but expensive , i've got it because i need it for work , but for plain editing i find that the shadow/highlight filter in CS is good enough for most exposure problems.
Thing is to get the exposure right in the first place , swans are difficult and i've shot hundreds of the bloody things , some succesful some not , rule of thumb , if it's blown out to the naked eye then it'll be blown out to the camera , a thing a lot of photographers forget when they shoot white objects in full sunlight .
Spot metering is an option , but it underexposes the surroundings , so use it carefully .

B..

[Stephen]

Re: Recovering highlights

I'll accept your point about true blown highlights containing no information to recover. However the fact remains that in a lot of cases where the histogram shows blown highlights, ie off the scale on the right, often referred to as clipped highlights, it is possible to recover them.

I'm not a great fan of the shadow highlight tool in CS If you know how to use it properly it can give a good result, but I've seen too many images where its obvious its been used and highlights especially are rendered grey.

The thing with Lightroom is that it does a much better job, and the key thing is that when working with Raw files its working in 16bit mode, therefore enabling a higher dynamic range to work with the tones. Part of the beauty of Raw and something many photographers still don't appreciate

I think anyone working with jpegs from the camera is possibly going to struggle more as they are in 8bit mode and the camera has already done the processing.

Photographing swans, which I only use as an example, in full sunlight is definately a nono though, as you suggest.

I agree about spot metering in such situations, frankly I tend to underexpose in preference, it is much easier to recover shadow.

[Ian]

Re: Recovering highlights

Hi Bob, I think I Stephen has something - not all 'blown' highlights are totally devoid of detail. What you see on-screen or on a print is not necessarily is all there is in the file. If you look for information, initially invisible, in very dark shadows or very light highlights, you can often be surprised at what can be recovered. It's easier with shadows though, of course.

Ian

Ian

[Archangel]

Re: Recovering highlights

Digital cameras record 256 shades of brightness, from 0 = pure black to 255 = pure white. So in every pixel captured, it is assigned a value of brightness between 0 to 255.

Clipped highlights are those highlights that have saturated the A/D converters and have a value of 255.
There is no information contained in the clipped highlights and also there is no any type of post processing that can do anything, except trying to guess/fake of what probably has been there.
The RAW to JPEG converter simply discards the highlights present in the RAW data by compressing them all to the max value of 255.
RAW mode does offer a finer resolution of light levels and also a wider dynamic range and can somehow help in most situations, but not at all times.

A solution is to decrease Exposure Compensation and switch to Center Weighted Average metering type or even in Spot in very harsh situations.
Also there is a need to use the lowest possible ISO as there is a need to minimize noise in order to pull out details in the shadowed parts.
Exposure Lock is also an option to consider in addition to all the above.


George

[Ian]

Re: Recovering highlights

Digital cameras record 256 shades of brightness, from 0 = pure black to 255 = pure white. So in every pixel captured, it is assigned a value of brightness between 0 to 255.

Clipped highlights are those highlights that have saturated the A/D converters and have a value of 255.
There is no information contained in the clipped highlights and also there is no any type of post processing that can do anything, except trying to guess/fake of what probably has been there.
The RAW to JPEG converter simply discards the highlights present in the RAW data by compressing them all to the max value of 255.
RAW mode does offer a finer resolution of light levels and also a wider dynamic range and can somehow help in most situations, but not at all times.

A solution is to decrease Exposure Compensation and switch to Center Weighted Average metering type or even in Spot in very harsh situations.
Also there is a need to use the lowest possible ISO as there is a need to minimize noise in order to pull out details in the shadowed parts.
Exposure Lock is also an option to consider in addition to all the above.


George

Hi George,

That technical information is all very well (though I think you are incorrect in assuming that the A/D conversion is limited to 8-bits resolution), but it doesn't really address the 'visible' aspect of lowlights and highlights. Just because what one can see on the screen may look like white (and so presumably 100% saturated) does not mean it really is saturated. This is because screens have a limited ability to display density variations that humans can distinguish at extremes of luminance.

So, what I am saying is that don't assume highlights are totally saturated even if they look like that - there is a reasonable chance you can bring out some detail by careful manipulation of these areas.

Here is an example:

http://diabolo.ifn.fr/imgs/E1-iso100-HR+sharp.html

Also, while it's true that in most colour images the colour channels are 8 bits wide (0-255), RAW images contain a wider range (typically 12 bits and sometimes claimed to be higher). You can export from RAW with a 16 bit range (though not in JPEG) and this gives even better latitude for recovering over (or under) exposed regions.

The luminance scale need not be linear, anyway, so a camera could pack more resolution into one end of the scale than the other. So in theory, there could be a lot more information waiting to be retrieved from very bright highlights.

* The consensus does say that it's easier to recover from over-dark shadows than over-exposed highlights, so it's wise to expose for retention of highlights. However, of course you need to be careful when doing this as the whole picture could become too dark. For example, if photographing a swan using spot meter mode, I'd be tempted to combine this mode with a some positive EV compensation as metering on white feathers will no doubt result in overall underexposure. Another strategy would be to use bracketing.

Ian

* This sentence has been corrected, see here.

[Archangel]

Re: Recovering highlights

Hi George,

That technical information is all very well (though I think you are incorrect in assuming that the A/D conversion is limited to 8-bits resolution), but it doesn't really address the 'visible' aspect of lowlights and highlights. Just because what one can see on the screen may look like white (and so presumably 100% saturated) does not mean it really is saturated. This is because screens have a limited ability to display density variations that humans can distinguish at extremes of luminance.

So, what I am saying is that don't assume highlights are totally saturated even if they look like that - there is a reasonable chance you can bring out some detail by careful manipulation of these areas.

Here is an example:

http://diabolo.ifn.fr/imgs/E1-iso100-HR+sharp.html

Also, while it's true that in most colour images the colour channels are 8 bits wide (0-255), RAW images contain a wider range (typically 12 bits and sometimes claimed to be higher). You can export from RAW with a 16 bit range (though not in JPEG) and this gives even better latitude for recovering over (or under) exposed regions.

The luminance scale need not be linear, anyway, so a camera could pack more resolution into one end of the scale than the other. So in theory, there could be a lot more information waiting to be retrieved from very bright highlights.

The consensus does say that it's easier to recover from over-exposed highlights than over-dark shadows, so it's wise to expose for retention of highlights. However, of course you need to be careful when doing this as the whole picture could become too dark. For example, if photographing a swan using spot meter mode, I'd be tempted to combine this mode with a some positive EV compensation as metering on white feathers will no doubt result in overall underexposure. Another strategy would be to use bracketing.

Ian

Ian,

When I wrote: "Clipped highlights are those highlights that have saturated the A/D converters and have a value of 255" I was thinking of JPEGs, since in JPEGS recover of clipped highlights is harder than in RAW.

RAW to JPEG conversion is down to 8 bits.
RAW to TIFF is 16 bits.
RAW by itself is 12 Bits which means that there can be 4096 different shades of brightness for each pixel.
So of course A/D Converters are not limited to 8 bits and 256 shades of brightness.

I didn't assume that highlights are totally saturated because they look like that in the screen. I was talking from a technical point of view, not of how it may look onto someone's screen or eyes.

The photo example you supplied shows that not all blown highlights are able to be recovered, which is true and with which I never disagreed.

And yes in theory a lot of things are being implied, but in practice things might differ. So how much of clipped highlights can be retrieved, remains to be seen in practice, regardless of how much information can possibly be there in theory in order to be retrieved.
Yes the consensus says that yo can retrieve from over-exposed highlights, but not from clipped ones. So we agree here too.
I suggested Center Weighted Average" metering type and "Spot" as a second alternative.

Actually I don't see any disagreement, but only misunderstanding.
I speak only perfect Greek


George

[yoshi]

Re: Recovering highlights

The consensus does say that it's easier to recover from over-exposed highlights than over-dark shadows, so it's wise to expose for retention of highlights.

Hi Ian,
I find this thread interesting as I occasionally suffer from "blown" highlights. I'm interested to know more about good features of various softwares - though prefer an affordable/user friendly one. OTOH i agree with bigbob in that what is more important is to expose properly from the very beginning. As my DSLR has no spot measuring function, I think I will use again for a while my sleeping spot meter for the coming flower season.

Hopefully this thread continues a bit more. Isn't there anybody else who sometimes suffers from (semi-) blown highlights?

yoshi

P.s. incidentally, Ian, do you mean " it's more difficult ..." in the above quoted message?

[bigbob]

Re: Recovering highlights

The apparent misunderstanding about lost or clipped highlights comes from Stephens use of RAW files with lightroom , yes RAW gives you a lot more exposure latitude than Jpeg and 16bit files will have more information than 8 bit , but i still stand by my original post by saying that blown highlights cannot be recovered .
You can drag some shades of grey out sometimes but these look unnatuaral and normally are followed by lines around the edge of the pixels which do show in printing , it's best to try not to point the camera at any bright highlights in the first place .
I use RAW and lightroom for work , but for recreational shooting i use Jpeg which i guess 80% of the members on here do (although i'm willing to be proved wrong ).
RAW files are invaluable in mixed lighting and generally where you're unsure about W/B and exposure , but the sizes are large , they take longer to write to the card and postprocessing can be a real pain , even using Capture1 and batch processing not all shots need the same values .
I'll stick to CS and Jpeg and try to get my exposure nearly right to begin with .

B..

[Ian]

Re: Recovering highlights

Hi Ian,
I find this thread interesting as I occasionally suffer from "blown" highlights. I'm interested to know more about good features of various softwares - though prefer an affordable/user friendly one. OTOH i agree with bigbob in that what is more important is to expose properly from the very beginning. As my DSLR has no spot measuring function, I think I will use again for a while my sleeping spot meter for the coming flower season.

Hopefully this thread continues a bit more. Isn't there anybody else who sometimes suffers from (semi-) blown highlights?

yoshi

P.s. incidentally, Ian, do you mean " it's more difficult ..." in the above quoted message?

Hi Yoshi - yes, well-spotted, I wrote the opposite of what I meant and I will correct that sentence in original post (it was very late and I was very tired!)

Ian

[coupekid]

Re: Recovering highlights

Have you ever noticed how when photographing certain things, unless you underexpose by a considerable amount its not easy to avoid blown highlights.

Swans are one such thing that you can have great difficulty with, and its usually the case that there are some blown highlights somewhere in the swans plumage.

Adobe Lightroom seems to have made recovering such highlights much easier. The exposure tools especially the Recovery tool make it a breeze and just to help you a little more you can switch on the highlight indicator and see them disappear as you move the slider.

Here's a shot taken recently of a swan where the blown highlights have been recovered. Lightroom really is one cool program.

Hi Stephen,

How does this compare with the one which I favour, and that is the shadow/highlight tool in CS2?

[Ian]

Re: Recovering highlights

Hi Stephen,

How does this compare with the one which I favour, and that is the shadow/highlight tool in CS2?

Ah! Stephen doesn't favour the s/h tool as it is often abused. Personally, I like it as it is a quick and convenient way to lift pictures, but it needs to be used sparingly. I rarely set it to more than 15%.

Ian

[Bearface]

Re: Recovering highlights

Personally, like Stephen, I shoot only in RAW (both for my personal work and my everday professional work) and have done so for well over two years now. The simple reason for this is that if you want to combine the optimum image quality with the ultimate control over your exposure, colour balance, sharpness and more or less every other aspect of your image, RAW is definitely superior to JPEG. Sure, JPEGs are processed in-camera and therefore offer a more polished "instant" result for those who want that sort of thing but for many, RAW files and the extra control / quality available are hard to ignore.

If you're using fast media cards, a quick camera and have decent computer power, your work-rate and flow are hardly compromised at all by using RAW, although intially the whole process admittedly requires some adjusting to. That said, if you don't require the optimum in terms of quality and do not need to control the individual image parameters of your image, then high-quality JPEGs are not to be sniffed at; far from it.

As for blown highlights, well RAW has consistently allowed me to recover visibly blown highlights from a number of shots, and I know for a fact that for most of them it wouldn't have been possible had those images been JPEGs. At the Adobe seminar last week, we all had access to shots which on-screen appeared to be over-exposed in places, however in Lightroom it was possible (in fact it was ridiculously easy) to recover these areas - and some significant levels of detail - by using a simple slider. As Bob has said, it's probably technically impossible to recover a "true" blown highlight, but as this is a medium governed by each individual's perception of tones and colours (almost entirely), the reality is somewhat different. A histogram can tell you a lot, but it doesn't see what we see