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02-04-2009, 08:53 AM   #1
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Enhanced Dynamic Range

My K200d (and I think the K20d as well) has the option when setting the ISO to enhance the dynamic range, thus reducing the sensitivity to 200-1600.

My question is, what does enhancing the dynamic range actually do? I read the manual. It vaguely deescribes it as increaasing the ratio of dark to light - what ever that means. When would I idealy use this feature? What advantage or disadvantage does it present to images? I've used it and can't tell any difference.

Could someone please explain to this newby, in layman terms, what dynamic range is, and why and when enhancing it is helpful?

02-04-2009, 09:31 AM   #2
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It gives you a little bit more leeway for exposure when you have extreme range between shadows and highlights, i.e. the camera will try to retain more details in the shadows/highlights than if the EDR wasn't activated. Since there is no free lunch, you also get a somewhat noisier picture, especially in the shadows.
02-04-2009, 09:32 AM   #3
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The effect is supposed to be that you can get more detail in your shadows, without blowing out your highlights. Normally, in high contrast scenes (ones with light lights and dark darks) if you expose high enough to give you lots of shadow detail, the highlights have to be blown. And if you expose to preserve the highlight detail, the shadows are pretty dark.

As for what it *does*, it's absoutely nothing you couldn't yourself in post procesisng - by exposing to preserve highlights and then raising the shadow levels using curves or a similar editing tool.
02-04-2009, 09:37 AM   #4
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QuoteOriginally posted by drjaxon Quote
My K200d (and I think the K20d as well) has the option when setting the ISO to enhance the dynamic range, thus reducing the sensitivity to 200-1600.

My question is, what does enhancing the dynamic range actually do? I read the manual. It vaguely deescribes it as increaasing the ratio of dark to light - what ever that means. When would I idealy use this feature? What advantage or disadvantage does it present to images? I've used it and can't tell any difference.

Could someone please explain to this newby, in layman terms, what dynamic range is, and why and when enhancing it is helpful?


I haven't used it yet on my K20D, but the operating manual indicates that when you turn it on it makes ".....it more difficult for bright areas to occur in the image...."
Not sure if that helps (clear as mud to me) ;-) but maybe combined with whatever it says in the K200D manual it might start to make sense?

Tim

02-04-2009, 09:46 AM   #5
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Maybe this thread will be usefull for you: LINK
02-04-2009, 11:01 AM   #6
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There are lots of threads on this that get into more technical details. I did a test myself a while ago that demonstrates one aspect of the feature on a red wagon: https://www.pentaxforums.com/forums/247838-post57.html

Now you basically said you wanted a layman's explanation for a newby. Here is mine:

The feature is most useful when you are taking a picture with very high contrast. In other words, very bright to very dark areas (outdoors in full sun typically). In scenarios such as that, the very bright areas can "clip." In other words, be brighter than the ability of the sensor to register detail. In cases like that, EDR will help make sure that the highlights don't clip. That comes at the expense of some extra noise in the dark areas.

When I first read about EDR, I thought it was a way to get more detail in dark areas. In fact it is just the opposite. It is a way of getting more detail in very bright areas by preventing clipping. I have found that I rarely need to use EDR. Pentax exposure metering is typically very protective of hightlights, so I don't usually have clipping problems.

Last edited by PentaxPoke; 02-04-2009 at 11:13 AM.
02-04-2009, 11:40 AM   #7
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It appears then that what it does is reduce the bit-depth of the image, rather than increasing it, which one would think that high dynamic range -meant-.
02-04-2009, 11:53 AM   #8
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QuoteOriginally posted by Sodbuster Quote
It appears then that what it does is reduce the bit-depth of the image, rather than increasing it, which one would think that high dynamic range -meant-.
That may be one way to look at it. "Expanded Dynamic Range" must have been coined by a marketer, not an engineer. You can't increase the dynamic range of a camera. That is fixed by the physical limitations of the sensor. EDR simply allows you to take an image of a scene that has high dynamic range, and "squeezes" it into the range of the sensor by reducing contrast, and shifting the highest peak to the left to prevent any clipping.

I am not saying it is a bad thing, it is just a misleading feature name. The other camera brands have the same feature, but different names: Nikon calls it "D-Lighting" Sony calls it "Dynamic Range Optimizer," Canon calls theirs "Auto Lighting Optimizer." EDR is the most misleading name of all 4. It really would be more accurately named: "Dynamic Range Reduction" but to the uninformed "reduction" has a negative connotation. Sony and Canon have much more appropriate, yet still positive names for this feature.


Last edited by PentaxPoke; 02-04-2009 at 12:05 PM.
02-04-2009, 01:15 PM   #9
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QuoteQuote:
PentaxPoke:I am not saying it is a bad thing, it is just a misleading feature name. The other camera brands have the same feature, but different names: Nikon calls it "D-Lighting" Sony calls it "Dynamic Range Optimizer," Canon calls theirs "Auto Lighting Optimizer." EDR is the most misleading name of all 4. It really would be more accurately named: "Dynamic Range Reduction" but to the uninformed "reduction" has a negative connotation. Sony and Canon have much more appropriate, yet still positive names for this feature.
I agree, 100%. Was this done by a marketer or a want-to-be profiteer?
02-04-2009, 02:39 PM   #10
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QuoteOriginally posted by PentaxPoke Quote
When I first read about EDR, I thought it was a way to get more detail in dark areas. In fact it is just the opposite. It is a way of getting more detail in very bright areas by preventing clipping.
Seems to me it does either or both, depending on where you set your exposure. Youa re right that if the was exposure to a place where the highlights were going to clip, this will prevent that - thus giving you more highlight details. But if your exposure is set to a place where the highlights *don't* clip, then the result should be more shadow detail.

QuoteQuote:
"Expanded Dynamic Range" must have been coined by a marketer, not an engineer. You can't increase the dynamic range of a camera. That is fixed by the physical limitations of the sensor. EDR simply allows you to take an image of a scene that has high dynamic range, and "squeezes" it into the range of the sensor
There's another aspect to the meaning of "dynamic range" that makes the phrase "expanded dynamic range" even more ludicrous in one sense, but also more logical in another. The maximum dynamic range of every single digital camera, every single film, every single painting every painted is exactly the same: it goes from black to white. That is, the physical picture itself goes from black to white. No digital camera can produce a black blacker than the darkest ink used in producing the print, nor a white brighter than paper the image is printed on.

And make no mistake, this is *not* a particularly large dynamic range. It is far smaller than the dynamic range of most real world scenes. Take the blackest object you can find and the whitest object you can find. Put them both in the same (medium intensity) light. Now look around the room and find some shadow areas. Any reasonably dark object - not just black objects - in a shadow is going to be *darker* than that blackest-of-black object in the light. Converse, put the objects in a shadow and look around the better lit areas of the room. Now any reasonably light-colored object - not just white objects - is going to be *brighter* than the whiter-than-white object in the shadow.

What this says is that no matter what light you look at your print in, there will be real world objects that are both darker than the darkest black in your print and brighter than the whitest white. And no camera in the world can change that fact. The dynamic range of the print is from black to white, period. Does matter what the scene being represented was or what camera was used to record the image. The print goes from the black of the the ink to the white of the paper, and that's not a very large range.

In order to be "telling it like it is", a camera would have to look at your blackest and white objects in the same light and make them come out pure black and white on the print. That way, a snapshot of your black and white objects would appear just like the objects themselves when viewed in the same light. And a snapshot of that snapshot would be the same. But as far as I know, *no* camera does that. They *all* compress the dynamic range of the scene so that if the white object comes out white, the black object comes out grey, leaving room for objects in the shadow to come out darker. And if you expose to make the black object truly black, the white object will come out grey, leaving room for objects that are in more direct light to come out brighter. Meaning any snapshot of the black and white objects next to either will be compressed relative to that actual objects. And a picture *of* that snapshot will compress the range even more, and so on.

So what changes from one camera to another is how the real world maps to that range of black to white. If we say one camera has higher dynamic range than another, what we *really* mean is that it is able to take a wider range of values from dark to light and squeeze them into that same print range of black to white. Which is to say, it compresses the dynamic range of the real world to make it fit the fixed black-to-white range of a print. I don't care how many bits you have to represent different *gradients* between black and white in that print - you're not going to get blacker than black or whiter than white in a print.

So it's *already* a misnomer to talk in terms of one camera having higher dynamic range than another. They are *all* identical in the dynamic range they *produce*:. black to white, period. What we really mean is that one camera can take a wider dynamic range in the real world and squeeze it into the black-white range on the print. And the D-range feature does this, too.

So if you accept the ridiculousness of claiming that one camera has higher DR than another but understand nonetheless what is really meant by that, the idea of saying that the D-range feature also increases dynamic range is not more ridiculous.

It's only if you choose to interpret "dynamic range" in terms of the number of discrete values that can be *produced* between white and black that bit depth comes into it - and then, that becomes the one and only determining factor.
02-04-2009, 09:10 PM   #11
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I would have to agree that the name is really misleading on all parts with any manufacturer. It's really no different than saying AdobeRGB represents more colors than sRGB. In reality it represents a larger range of colors given that it is at the expense of color accuracy across the board(density). If you only have a finite amount of room to store something, that's all you have... All that's left is interpretation. The D-Range setup is more for highlights than anything. I did a somewhat scientific test here. You really have to ask yourself what it is you need in your images. If it's your livelyhood, shoot raw. If you enjoy taking pictures and are in a place/time where you might have a few "keepers", shoot raw. If you just want to capture the moment - something for only you and those close to you, shoot raw or jpeg with or without D-Range. If you don't mind jpeg, by all means use d-range. It gives a more film-like quality in response to light.

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02-04-2009, 09:12 PM   #12
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I get it now.

Uh... yeah. Thats what I thought. Wow, what a great first day in EDR school. I liked those links included. Pictures are so much more eloquent. Maybe thats why I like cameras.

So... if I wanna take a picture of snow capped mountains and the green forest below, EDR could help if the light was in front of the scene? Or, at least to some extent, I could capture a better image without loosing the mountains in the sky or the forest in the shaddows.

Is there some slick way for me to find thread links, like those sent, in this forum? I tried the "Search" and typed in "dynamic range" and only got a handfull of unrelated articles.

You guys are great. I appreciate your thoughtful answers - its as if I have a group of new, wise friends, who may think I'm an idiot, but will never let me know it.
02-05-2009, 12:54 AM   #13
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QuoteOriginally posted by drjaxon Quote
So... if I wanna take a picture of snow capped mountains and the green forest below, EDR could help if the light was in front of the scene? Or, at least to some extent, I could capture a better image without loosing the mountains in the sky or the forest in the shaddows.
Yes, that is the kind of scene where EDR could actually help. If presented that situation, I would take a picture and see if the histogram clips on light end. If so, then turn on the EDR. I rarely find the need to use it though.

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02-05-2009, 04:10 AM   #14
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IMO it give more noise ... so I stay away from it ... PP myself for my own EDR and the handle noise with a PS plugin.
02-16-2009, 01:55 PM   #15
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More EDR Qs

Great info. So I've been shooting some ducks lately... Attached below are some images of a Mergansers on the Huron River. They were taken on different days. The first may have been overcast, I can't remember, but the 2nd was on a sunny day for sure. Both images were taken, hand held and SR on, with the K200d with a Tokina RMS 400 and cropped to around 200 percent - plus or minus.

The first image is at 1/350 at (I think) f4.0 at ISO 100, d-range switched off.
You can see great detail in the white of the bird, but the head is quite dark.

The 2nd image was taken at 1/90 at (I think) f8 or 11, ISO 200 with d-range switched on. You can see on this one, I got nice color and exposure on the heads, but the white is blown out with little detail. Apparently the EDR did not help here. Should I have underexposed and brightened in PP? Or is such an image with both the dark head and white body exposed well for detail not possible due to mechanical/electronic limitations?

Another problem: CA. The first image shows quite a bit of CA at the white neck and dark head junction line. The 2nd image has CA less noticeable, I think, because I stopped up the f-stop to mid-range, and used the hood. This lens can have noticeable CA and purple fringing at wide open apertures. I haven't tried the Pentax Photo Laboratory software to correct this. Would it make any difference?
Attached Images
   

Last edited by drjaxon; 02-16-2009 at 02:35 PM.
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