Author Topic: exposure times for HDR  (Read 6356 times)

Offline jo

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Re: exposure times for HDR
« Reply #15 on: March 07, 2009, 10:59:45 PM »
Hi Bill,

Well, in this tutorial:

http://www.aguntherphotography.com/tutorials/raw-hdr-processing.html

He's just using the combination of several 14 bit images to make one 32 bit image. With TG2 images you don't need to bother with that. Just do the tonemapping to get the effect you want.

However I'm sure some of the effects people get from processed HDR images also come from the way they combine the lower dynamic range images into the single image. I would imagine that the process doesn't give as "pure" a 32 bit image as TG2. You can always experiment with saving TG2 images generated by TG2 with different exposure settings and then combining them if you feel like it. Strictly speaking there is no need, but you may find you can process them in such a way as to give a particular result.

BTW, anything over 8 bit is an HDR ( high dynamic range ) image really. A 14 bit RAW image from a camera is already HDR, it has a far greater dynamic range than an 8 bit JPEG from a camera.

Regards,

Jo



Offline Mohawk20

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Re: exposure times for HDR
« Reply #16 on: March 07, 2009, 11:27:03 PM »
So basically what they're saying is that you can use the exr output to get several exposures from one render and combine them to a hdri image that is to your liking.
But you don't have to use a time consuming method (though you probably do it very easily), since all the info is allreasy in teh exr, so if you tweak the single image in a program like PhotoMatix (or even PhotoShop), you might get the same results, or even better.


One difference I noticed was when increasing exposure settings in photoshop. A normal bmp output of a transparent blue rock on a black background will have the black background go gray when increasing the settings. The exr however kept the background black, while the internals of the rock showed up really good.

If you want, you should really try it out, but you can still use your 'old' method if that works for you.
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Offline matrix2003

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Re: exposure times for HDR
« Reply #17 on: March 09, 2009, 09:58:28 PM »
Thanks Jo and Mohawk.
"The devil is in the detail"

 ... I guess my point was, the technique if used properly has some interesting results.
The way you postwork the images definitely can dramatically change the output,
beyond the capabilities of strictly processing EXR images in photomatrix or photoshop.
 
So my best advice should have been: Save all renders in the .EXR format, and post process any way you are comfortable with.  ;D
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Offline gregsandor

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Re: exposure times for HDR
« Reply #18 on: March 10, 2009, 02:39:38 AM »
To expand upon Jo's comment about the difference between TG's one-shot HDR production vs real-world, you could use TG and very slightly change the sun angle, cloud position, light intensity, etc. then combine the renders.  This will go a step toward recreating the natural variation in hand photographed HDR images.

Offline rcallicotte

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Re: exposure times for HDR
« Reply #19 on: March 10, 2009, 03:00:03 AM »
Hey, that's an interesting possibility.  I'll try it!

To expand upon Jo's comment about the difference between TG's one-shot HDR production vs real-world, you could use TG and very slightly change the sun angle, cloud position, light intensity, etc. then combine the renders.  This will go a step toward recreating the natural variation in hand photographed HDR images.
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Offline matrix2003

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Re: exposure times for HDR
« Reply #20 on: March 10, 2009, 11:17:01 PM »
@gregsandor  There you go!  Three images with slightly different hues of cloud color.  Say pink, salmon and orange for a sunset.
Three with whacky numbers you would never use.  Three with crazy post work or -or three or more all rendered in T2, slightly modified.

I was suggesting  'think outside the box', when I said that I tweak the individual files vs. tone mapping a single image.
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« Last Edit: March 12, 2009, 09:34:28 AM by matrix2003 »
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Offline Marcos Silveira

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Re: exposure times for HDR
« Reply #21 on: March 13, 2009, 03:21:08 PM »
What is special about HDR images, I think they're horribly fake!!! Could someone send a link to some examples to make me change my mind?!?

Offline rcallicotte

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Re: exposure times for HDR
« Reply #23 on: March 13, 2009, 03:54:56 PM »
Also using HDRI for not only lighting but shading will do wonders. Pixar's Wall-E used quite a bit of HDR to realistically render out metal and plastic surfaces for several of there models.

Offline Saurav

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Re: exposure times for HDR
« Reply #24 on: March 13, 2009, 09:54:53 PM »
What is special about HDR images, I think they're horribly fake!!! Could someone send a link to some examples to make me change my mind?!?

I shot this photo in Nepal a few months ago. 3 exposure of (+2, 0, -2) photos -> HDR -> tonemapped in photomatix. If you tried to shoot LDR or even shoot in RAW the highlights (snow) would blow out and you would loose a lot of details in the scene. HDR has it's place in photography, it can definitely be made to look natural. It's just that most people don't choose to process it that way because they like the 'fake' look. Personally I like the natural looking HDR photos more.

Offline rcallicotte

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Re: exposure times for HDR
« Reply #25 on: March 14, 2009, 03:12:36 AM »
Beautiful photo, Saurav.
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Offline Libra

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Re: exposure times for HDR
« Reply #26 on: November 05, 2017, 02:45:02 PM »
In this article you'll find some tips on exposure value needed to create HDR photography  https://aurorahdr.com/what-is-hdr-photography.


 

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