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 Post subject: HDR Experiment
PostPosted: Thu Jul 05, 2007 6:01 am 
First of all I want to say "thank you" to Mango Man for putting me onto HDR. I'd heard of the term before, but thought it was something like HDTV...High Definition something and assumed it was just some kind of image size. When I read his post and how he was interested in shooting HDR images, I thought that was then something I could do with my D80 so I started researching it.

Anyway, enough rambling...I went out this morning and took some bracketed shots round the back of my house and it seems to have come out really well. I just set the camera to take 3 images and I could have sworn I set it to take them in 1 stop brackets, but it took them in 2/3s brackets instead...maybe that's just as well otherwise I'd have over and under exposed too much.

Image

What do you think? How much do people usually compensate by when they bracket images for HDR?

I have to say the HDR merge function in Photoshop is excellent! I don't have a tripod so the exposures were all hand-held and then aligned, merged and cropped automatically. My PC almost had a fit with it's little 256mbs of RAM, but it got there in the end....took quite a few minutes :)

Shame about the power cable (or maybe it's a phone line) running through the image. If I spent the time I could probably get rid of it in PS, but this was just an experiment to see how it worked.

The 3 original exposures are on Flickr for comparison.

If anyone's got any tips on post processing HDR images, I'd be really interested in hearing them. Mango Man, if you read this...I can see why people are interested in HDR now...thanks :)


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 Post subject:
PostPosted: Thu Jul 05, 2007 6:22 am 
I've just been browsing round Zorro's (another user on this forum) Flickr page and he has some quite awesome HDR examples.

http://www.flickr.com/photos/zorro2000/


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 Post subject:
PostPosted: Thu Jul 05, 2007 8:21 am 
Wow...Zorro's are excellent!! Zorro, please share...how are you doing that?


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 Post subject:
PostPosted: Thu Jul 05, 2007 9:19 am 
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Hi all. My ears were burning :lol:

I've only been playing with HDR for a few days too and it's not that easy. The most difficult thing I think is recognizing what will work and what won't. It's also far too easy to get carried away and produce something that's over the top.

Some of my pictures were specifically taken with HDR in mind and so were bracketed at the time of capture. Others are images in my back catalogue that have been adjusted during conversion from RAW.

An important thing is to ensure the "middle" exposure has a broad range of detail. I'm also struggling with RAW. I'd have thought using RAW images would produce better results but so far this hasn't proved to be the case. Maybe it's down to which software I use. I've been using Photomatix up to this point but last night I got Artizen HDR, which seems like it's probably better but it's also a lot more confusing too.

One distinct benefit of shooting in RAW is that I have the latitude of being able to adjust the exposure in ACR on conversion. This means that, in theory at least, I only need one well-exposed image which can be saved as three or five different exposures, depending on the range in the original photo. This also makes your entire back-catalogue of RAW files candidates for HDR.

Zorro.

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 Post subject:
PostPosted: Thu Jul 05, 2007 9:46 am 
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Hi Zorro!

Do you have a non-HDR version of "Windswept HDR" on flickr? Would love to see the original posted!

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 Post subject:
PostPosted: Thu Jul 05, 2007 9:56 am 
Hey Zorro,
Was hoping you'd look in sooner or later :) Your pictures are really great! When I saw yours after I posted my first image I felt so embarrassed...yours make mine look like just nice snapshots!!

Here's another effort of mine. It was bright this afternoon with nice fluffy white clouds so I went out and tried again:

Image

I tried shooting the 3 images in Raw this time, but what a nightmare merging them to HDR with my PC. Think I'll have to stick to Jpeg until I get some more RAM installed!

I tried to be a bit more daring with the colors this time, but I know what you mean, it is really easy to go too over the top. I'll have to do more research though because to me it still looks like just a nice snap :(


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 Post subject:
PostPosted: Thu Jul 05, 2007 10:41 am 
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It's a nice image though, I rather like it.

I think it's important to have as much contrast in the scene as possible. Your image here looks a bit flat maybe, not sure. The vast majority of my attempts turn out like yours though, so I wouldn't worry about it. I'm not entirely sure what's the best criteria for HDR. When I find out I'll let you know.

I've tried it now with 3, 5 & 7 exposures and to be honest there's no advantage in using 7.

I'm going out today specifically to look into this because my favourite weather is here. Sunshine & showers.

I need to find the "HDR Merge" function you talk of in Photoshop. I haven't seen that yet.

Zorro

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 Post subject:
PostPosted: Thu Jul 05, 2007 12:02 pm 
Yeah, I think maybe if I'd cropped it more, it wouldn't look so flat, I don't know. Practise makes perfect I guess....I hope! I'll certainly be thinking more about what would make good HDR images when I'm out. At the moment I'm just thinking landscapes with blue skies and clouds and sunsets, but obviously by looking at your images, there are many different situations where HDR images can look really effective.

I'm going to do more research and see what subject matters others use and try and find other techniques.

I've read that some people use up to 5 and 7 exposures. That would definitely blow up my PC! It seems a lot of people compensate plus and minus 2 stops so I'll give that a try sometime, but I'm sure that would just blow out all the highlights and shadows rendering the whole concept pointless.

In PS, the merge HDR function is under file - automate - merge HDR

There a box to click if you want PS to align the exposures for you and some people say not to use it, but I've found it works perfectly for mine and without a tripod, I need it!

Good luck with your sunshine and showers...look forward to seeing your results :)


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 Post subject:
PostPosted: Thu Jul 05, 2007 1:36 pm 
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I've tried the merge thing in Ps now and to be honest the results are pants. I'm maybe doing something wrong but my HDR's processed with PS just turn out flat, like yours. Have you tried Photomatix Pro?

Later on I'll try processing the same RAW images in both Photomatix and Ps and we'll see what the difference is.

Zorro.

P.S. - Weather's change from sun & showers to showers & torrential. I need to live in Spain!

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 Post subject:
PostPosted: Thu Jul 05, 2007 2:21 pm 
No, I'm just reading about it now. There's a really good article here:
http://www.naturescapes.net/072006/rh0706_1.htm that goes into HDR really indepth and in it they compare processing HDR images in PS CS2 and Photomatrix. It seems that Photomatrix is better, but it looks a lot more complicated. Still, if you want the best results then I guess you have to be prepared to work for it!

I've picked up a few good pointers from the article and things that I didn't realise before.

1) Maybe this is obvious to other people but it says to meter the whole scene first and then choose a good midpoint to lock exposure for the first shot. I was pretty much just pointing and shooting.

2) If you're using auto-bracketing then switch to manual focus so that you don't have to wait for the camera to auto-focus between exposures. Especially important for hand-held exposures like mine. I've been leaving mine on auto-focus.

3) For best results, shoot in RAW and convert before merging. Maybe that's where I went wrong because I didn't do that and I ignored the PS warning...oops! I'll have to give RAW another shot and convert this time.

I really wish the D80 was able to take more than 3 bracketed shots...if it could take 5 it would be great. They explain a way of being able to take a series of 5 exposures if you're camera can only take 3, which sounds good, but you really need a tripod for that because you have to make an exposure comp. adj. halfway through.

It'll be interesting to see the results of your comparison of the two programs.


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 Post subject:
PostPosted: Thu Jul 05, 2007 2:29 pm 
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Hi guys, I envy you playing around with HDR! But please for those who can only read and look, post the original (middle exposure) shot at flickr so that we can compare (before/after)!

B.t.w.: What does HDR do to clouds in landscape pics?

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Last edited by Thomas on Thu Jul 05, 2007 3:42 pm, edited 1 time in total.

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 Post subject:
PostPosted: Thu Jul 05, 2007 3:29 pm 
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Ah well, Photomatix can be tested for free. Nice idea!
As I don't have bracketed pics but shoot everything in RAW I just threw the single pic converter ("batch conversion single files") at a single pic :wink:
Oh boy, what a disappointment. The conversion really asserted my fear, that HDR is in reality reducing contrast as it amplifies the dark parts of the scene.
The other thing specific to single file conversion is the appearance of the dreaded noise: As the software amplifies the dark parts (we are talking about +2EV here!) it also amps the noise. This certainly can be eliminated with bracketed exposures as the longer exposure for the dark parts keeps the noise at bay!
On closer inspection it seems that noise is even amplified more :(
See on this comparative 100% crop here:
Image
The tone and brightness of the skin is similar, but the HDR'ed pic on the right certainly shows more noise :roll: Even in the sky?! :cry:

Some additional information: Photomatix made the skin +1EV, the top and jeans +2EV, the sky +0EV. Interestingly the clouds actually got a higher contrast at -0.5EV in the dark parts and +0.5EV in the bright parts depending on brightness.

Keeping you posted...

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Last edited by Thomas on Thu Jul 05, 2007 8:58 pm, edited 1 time in total.

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 Post subject: HDR (updated)
PostPosted: Thu Jul 05, 2007 7:53 pm 
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OK, here's an example of the results of the same HDR conversion in Photoshop CS3 & Photomatix Pro.

The original three exposure were RAW but as they were NEF's (which hold onto camera info) I converted them all to jpeg in an attempt to make a level playing field. It's also faster.

The only post-processing that was done was to crop all images to the same size (1680x1050) and the two final images were sharpened equally in Capture NX.

Like I say, I'm no expert here. This is the best I could do as regards a tutorial because I've never done anything like this before.

These are the three original exposures -

Image Image Image

This is what Photoshop came up with -

Image

This is what Photomatix came up with -

Image

This is a sreenshot to show the settings I applied in Photomatix -

Image

This is what Artizen HDR came up with, using default settings for the "Fattal" tone mapping generator -

Image

And this is a screenshot showing the default Artizen HDR workspace. As you can see, there are more options than I can shake a stick at, some of them work wonderfully well -

Image

For the record, this is the same job done with the original RAW (NEF) files in Photomatix. Make up you own mind -

Image
I hope this at least helps a bit. I'm sure a better result can be got out of Photoshop but I haven't found a way yet.

Sorry about the images being so small but the files were too big for my host at their original size (which of course I didn't find out until the very last upload).

The difference between the two results is huge though.

Contrary to what I've said before I find the HDR using RAW files as source to be the better result. I think it's often down to "operator error". :wink:

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Last edited by zorro on Thu Jul 05, 2007 11:12 pm, edited 1 time in total.

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 Post subject:
PostPosted: Thu Jul 05, 2007 8:13 pm 
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To be honest, the PS-merge is not so much different from the original_0EV. The Photomatix produces more drama with the RAW-merge topping the jpg-merge. I esp. love the clouds!
B.t.w. how do you do RAW-merge in Photomatix? With my NEF-RAWs all menu-items were grayed out!
B.t.w. the size is perfect to see the effect, perhaps not perfect enough to judge grain/noise. But that is no prob with three bracketed pics, isn't it?

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 Post subject:
PostPosted: Thu Jul 05, 2007 8:32 pm 
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I just merge RAW's in exactly the same way as with JPEG's. Are you using the demo? If so then maybe RAW conversion is disabled.

I can't figure out how to change parameters for HDR in Photoshop.

Zorro.

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