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03/24/2009 07:37:17 AM · #1 |
Hi all,
I have been experimenting with HDR photography and haven't had much joy with photoshop cs4.
Problem 1: 'halo noise from movement in the background even while using auto aligning'
Even using the auto align images options produces images which have a lot of noise generated from movements in the background. Even on a still day i took a series of 3 images (-2,0,+2) all less than 1 second shutter on a tripod and even over that time with the gental wind a few leaves moved around and the image is ordinary when viewed 100%. I get a halo around the leaves. On longer night exposures the halo goes crazy mainly from boats/ferries moving through my series of long exposures.
Problem 2: How to get those 'mystical' style images from HDR easily done in Photomatrix in photoshop cs4
while i don't actually like those 'mystical' style images you can make from HDR i figure once i can turn the dial right up to generate that image i will have control over the HDR and can dial it back. At the moment, using photoshop cs4 i haven't been able to 'turn up the dial' high enough to get any sort of detail that i like, let alone those bizzar 'mystical' images
I have been able to achieve this in Photomatix but i only have that on a trial basis.
I have generally been just trying to join (-2,0,+2) i realise that i can get a better effect with 7 or so images but the more shots i take, the more noise will be an issue
I know I could use the exposure feature in RAW and make several images from the same base raw image to get around the noise issue but i figure that kind of defeats the point of HDR. |
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03/24/2009 07:56:21 AM · #2 |
no software is going to completely sort out moving objects in different frames.
the only way to deal with that is psuedo HDR from 1 raw.
more frames will not increase noise, in fact the more frames the less you have to amplify the process and you will get less halos etc.
the ammount of exposures you need varies on each scene.
i start at 0 EV on the camera and step down a stop at a time, checking the histogram for each shot.
when you get to a point where there are no highlights blown you have gone far enough.
then i go and do the same for shadows, stepping up a stop at a time until the histogram shows that no shadows are clipped.
this way ensures you have all the detail in the scene that there is to capture.
hope this helps!!
ETA - i have PS CS3, but i have never used the HDR function.
i stumped up for photomatix.
Message edited by author 2009-03-24 08:00:48.
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03/24/2009 09:21:31 AM · #3 |
Originally posted by Dranium:
I have generally been just trying to join (-2,0,+2) i realise that i can get a better effect with 7 or so images but the more shots i take, the more noise will be an issue
I know I could use the exposure feature in RAW and make several images from the same base raw image to get around the noise issue but i figure that kind of defeats the point of HDR. |
You're operating on a misconception here. You do NOT get more noise by combining more exposures. If anything the opposite is true.
Your key concern when choosing which exposures to merge is this: the *brightest* exposure in your stack should be the one that has the shadows exactly as you want them, and the *darkest* exposure you use should be the one that renders the highlights exactly as you want them. Any exposures over or under those extremes will negatively affect the quality of the composite by making it too flat in the mid-tones. This starts to make more sense when you realize that tone mapping, an integral part of the HDR function is used to accomplish two things: it compresses the range of the raw composite into the viewable zones, and it introduces back into the midtones the contrast you have lost by compressing them.
Now, that tone mapping (in CS4 it's called shadow/highlight) is where the noise you're complaining about is coming from, basically. Extreme tone mapping introduces LOTS of noise to broad, flat expanses of tonality especially, as it attempts to force local area contrast where there was none to begin with. And that's your culprit.
The thing is, in all likelihood with your plus-2 and minus-2 exposures at least one of them is more extreme than it needs to be, and maybe both. So in your raw composite the highlights are possibly too "down" and the shadows are possibly too "up", and to make a decent looking image from that, the tone mapping is working overtime to "unflatten" a too-flat image, and you get noise.
As a rule, the largest spread you want between exposures is 1 stop, and half a stop is often better. By using a 2-stop range in both directions you're forcing the merge function to interpolate values, and that is not good. So if you really NEED a plus-2 and a minus-2 (and sometimes you might) then you also need a plus-1 and a minus-1 to go with them, making a base set of 5 exposures to merge. You'll get much better results from that.
Nevertheless, I find that most of the time 1 stop in each direction is the most I need and sometimes less. It's not unusual for me to do an HDR in 1/2 stop increments, ranging from plus-1 to minus-1/2, giving me 4 exposures, for example.
Hope this helps.
R.
ETA: Just read Dain's post. He makes sense re: checking the histogram, but for me it's so fast and easy to make multiple exposures that I just go way past what I expect is correct when I am shooting then sort 'em out later in the PP stage, where I examine the actual exposures and their histograms and decide which ones to use. Reduces the amount of actual thinking and second-guessing I have to do on-site. :-)
Message edited by author 2009-03-24 09:25:25.
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03/24/2009 09:43:54 AM · #4 |
| These two replies are a wealth of information for we lurkers here. Thanks. |
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03/24/2009 01:27:11 PM · #5 |
I asked this question about HDR software at FredMiranda.com this morning:
"azleader wrote:
Anyone have a preferred HDR solution??"
floris wrote:
"A grad ND or manual blending. HDR, as in automated programs like photomatix, are not a solution, they are a plague."
Take a look and I think you'll agree the responder is a great landscape photographer:
Floris van Breugel's Photography
Anyone here care to comment on his response? |
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03/24/2009 01:33:52 PM · #6 |
Originally posted by Artifacts:
I asked this question about HDR software at FredMiranda.com this morning:
"azleader wrote:
Anyone have a preferred HDR solution??"
floris wrote:
"A grad ND or manual blending. HDR, as in automated programs like photomatix, are not a solution, they are a plague."
Take a look and I think you'll agree the responder is a great landscape photographer:
Floris van Breugel's Photography
Anyone here care to comment on his response? |
He's very good, yes. And manual blending generates some very nice results if you have the patience for it. I don't think that HDRI is a "plague" though, just the crazy/wild application of it is offensive to a lot of people. You can use HDRI to produce very natural results (I've done it myself), and you can layer different HDRI results manually as well and use his same workflow for that. I've done that also.
The thing of it is, for producing local area contrast, nothing I've seen in the "straight" toolkit does that easily. So tone mapping, or some variant of it (shadow/highlight, topaz, whatever), used in moderation, and merged into otherwise-straight images, can give you the best of both worlds. And anyway, right now, at this point in time, I'm enjoying the more extreme areas of landscape imaging, so I'm happy.
I'm sure someday I'll calm down and be more rational :-)
R.
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03/24/2009 04:19:56 PM · #7 |
Thanks Robert... that was kinda what I was thinking to and appreciate you weighing in on the subject with similar views.
FredMiranda has some incredible photographers and is a treasure trove of information about very unique subjects and from top notch amateur and professional photographers alike. They are a bit medium/high format film biased and for good reason, but they are good!
To some of them a 5D Mark II is like a Kodak Brownie. LOL!!! |
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03/25/2009 07:38:11 AM · #8 |
| HERE is a great HDR tutorial. |
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03/25/2009 07:57:42 AM · #9 |
| I have reviewed a few different HDR programs on my blog and working on two others now. //www.tkrphoto.com |
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