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Old Jan 29, 2010, 3:22 PM   #1
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Default HDR of moving objects

I have been looking at a lot of HDR's recently online and have noticed a large number of HDR's with birds, tigers, lions, people, moving cars.... the are all well in focus and frozen in action.

My camera takes bracketed exposures at a rate of around 1 per second (very slow, i know). Are people really taking these pictures with 3 or more exposures, but are able to take them very very quickly, or are they doing psuedo HDR's. All the HDR's look fantasic and like real ones. Does anyone have any idea how they/you do that?

For reference, this site shows a couple of birds in flight in HDR. (4th and 6th picture from the top.)

Thanks,
-Eric
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Old Jan 29, 2010, 3:48 PM   #2
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There are two choices in Photomatix -- for moving water and leaves, or large objects like people or cars. Personally, if I could shoot RAW, I would do the HDR from a large RAW file.
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Old Jan 29, 2010, 7:03 PM   #3
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I don't see a huge difference between series processed with the "moving people" option and without in Photomatix. What I've done is to take the people from the exposure that is right for them and clone them onto the HDR picture, blocking out the blurred/ghost image part of the HDR. You can't always do that successfully, depends on the picture. DPHDR has a way of deleting ghosted images, but I didn't play with it. It looked (just reading the directions) like it would be really useful.
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Old Jan 30, 2010, 5:09 AM   #4
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if you shoot RAW you can do HDR from a single image, just load your image into a editor and increase exposure +1, then save as a new pic, do it again from the original only give it -1.
then your left with 3 images that you can load into Photomatix.
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Old Jan 30, 2010, 12:12 PM   #5
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Quote:
Originally Posted by Bynx View Post
There are two choices in Photomatix -- for moving water and leaves, or large objects like people or cars. Personally, if I could shoot RAW, I would do the HDR from a large RAW file.
This is my basic intention for using HDR. I rarely carry a tripod around with me, and expect to use one RAW shot to do the job. Photomatrix informs me that this is not as good as having three or more actual exposures, (They refer to this as "pseudo HDR) and I have no reason to doubt them...

But using a single RAW file certainly works!!!

While I take pride in capturing light and shadow in the same frame, not every shot I take is successful.

Dave
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Old Jan 30, 2010, 12:40 PM   #6
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Ya I dont understand that pseudo HDR term. A RAW file has more dynamic range than a jpeg so if you can break it up into 3 different range values and use them, then what's the difference between them and 3 range values of jpegs? Some cameras shoot RAW and also produce a jpeg. Well Id like someone who has such a camera to do an HDR with 3 jpegs and also a pseudo HDR with one of the RAW files and let us see the difference.
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Old Jan 30, 2010, 1:07 PM   #7
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Ya I dont understand that pseudo HDR term. A RAW file has more dynamic range than a jpeg so if you can break it up into 3 different range values and use them, then what's the difference between them and 3 range values of jpegs? Some cameras shoot RAW and also produce a jpeg. Well Id like someone who has such a camera to do an HDR with 3 jpegs and also a pseudo HDR with one of the RAW files and let us see the difference.
My understanding (and anyone and their mother-in-law can correct me) is that while RAW captures more data then a normal exposure, it is not quite the same as a digital negative. That some information is simply not there. What this means to me, (and where anyone can correct me) is that while I CAN bring out blown highlights, or shadows, the only reason that this is true is that 12 or 14, or 16 bit) has such a wide range that some of what is lost, is actually available. But this is Not the same as capturing the actual data with a lower or higher exposure. In other words, "cheating" because of a wider range of data, is not quite the same as the actual data. Dave
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Old Jan 30, 2010, 1:23 PM   #8
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If you shoot RAW, you can use your raw conversion software (some) to recover highlights, and brighten shadow areas, all in one conversion. IOW, you don't need to create 3 images to then convert to psuedo HDR. Neither method will give you what you will get with true HDR, using 3 or more exposures with at least a full stop between them. Biggest reason is that recovering shadow detail, while possible, creates a lot more noise. Removing the noise often is worse than leaving it alone.
My Dslr does better than my P&S due to the larger sensor size having significantly lower noise to begin with. Newer Slrs seem to be a good bit better than mine, so probably have more potential in this respect.

brian
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Old Jan 30, 2010, 2:06 PM   #9
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i don't think that photomatrix operates the same when using one RAW file. at least not from what I could tell when using 1 RAW for those barn pictures i took. it appears to just recover the highlight and shadow detail as best it can, and then tone-maps over it. i have tried to process a RAW into 3 images 1 step apart and then merge in Photomatrix and it doesn't turn out as well as just letting Photomatrix do its Pseudo-HDR algorythm.

in general RAW gives you about 1-1.5 ev headroom to pull back the highlights and recover shadows over jpeg. of course this will vary with manufacturers and how well their jpegs do.
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Old Jan 30, 2010, 3:52 PM   #10
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I kind'a feel that the discussion in the last 5 to 6 posts reall don't help ewheeler very much, as far as his original question was about moving objects in HDR and not so much as to what or how much on can do with a RAW-file.



Quote:
Originally Posted by ewheeler20 View Post
...Are people really taking these pictures with 3 or more exposures, but are able to take them very very quickly, or are they doing psuedo HDR's. ...
For reference, this site shows a couple of birds in flight in HDR. (4th and 6th picture from the top.)
I think Eric has forgotten to write down the link to this site, he is mentioning in his last sentence, but anyway lets concentrate on the question rather than discussing RAW-files as such.

If you look at vvcarpios thread: http://forums.steves-digicams.com/ar...ew-church.html in picture # 2 you'll notice a lot of pedestians walking across the frame of the picture of this NYC street-scene, and still - vvcarpio's shot is a HDR consisting of 3 different exposere, taken on after the other - with people moving in between shots! Also. The flags are moving in the breeze - there are no ghosting-artifacts there either - it has been "Gost Masked" in DPHDR.

How does he do that?

Well, vvcarpio has become a master of using DPHDR (and I wish he would give us some input of how he does it...) which allows you manually (and this is important!) to choose which of the ghostings in which exposure should be surpressed and which ones should stand. I have not come that far yet but I understand the principles. It's called "Anti Ghosting Mask" and lets you paint (in red) over the objects that are moving (ghosting-artifacts) in two out of three exposures. The last exposuer, whgis was NOT painted over - stands. Simple as that!

I have made a simple example to upload, just to give you an idea of how this works. In it you will see a car moving from right to left and in 1 of the exposures the car has been obscured by this red paint. Also, behind the car you see a person walking (2 ghosting-figures), I should have painted one of them as well.

You get my point? Its well and nice that Photomatix lets you tick off either background-movement (water, foliage) or 'moving objects' (like people, cars, etc.) - BUT, it does not let you decide what will be present in the final outcome. You are at the mercy of a software which does not think, but probably has some hundreds of examples in its own database and which will be used accordingly - sometimes with ridiculous effect.
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Last edited by Walter_S; Jan 30, 2010 at 3:58 PM.
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