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02/11/2008 05:37:57 AM · #1 |
To me, HDR is about using the most suitable and desired parts of ten or less images to create a high quality powerful image. Bearing in mind that no one object is to appears twice or more times in the same final photo.
Is this about right?
Message edited by author 2008-02-11 06:00:33. |
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02/11/2008 05:43:38 AM · #2 |
I would like a definition too! I love some of the HDR shots here but have absolutely no idea what classifies them as HDR. Not that i would be able to do any yet.... gotta learn photoshop!!!... but it definitely would be nice to know!
Maybe some genius/guru/Photoshop-whiz could do up a tutorial for complete and utterly unknowing persons like me.  HighNooner does not fit into the same class of mental midgets like me. He knows enough to be able to ask an intelligent question about it. :)
Message edited by author 2008-02-11 05:49:10.
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02/11/2008 06:19:42 AM · #3 |
See if this helps:
3 (or more) exposures of the same image stacked in such a way that the software subsitutes the underexposed shadows with properly exposed shadows from another frame, and substitutes the over-exposed highlights with properly exposed highlights form another frame, then assembles them into one image.
Here is where a picture is worth however many words that was:
Combined (then toned differently because I wanted to):
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02/11/2008 06:27:04 AM · #4 |
Originally posted by Brad:
See if this helps:
3 (or more) exposures of the same image stacked in such a way that the software subsitutes the underexposed shadows with properly exposed shadows from another frame, and substitutes the over-exposed highlights with properly exposed highlights form another frame, then assembles them into one image.
Here is where a picture is worth however many words that was:
Combined (then toned differently because I wanted to):
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So basically you are using the part or parts from each one of the photos that you like and think will serve your final photograph better!!
This is good work by the way!! |
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02/11/2008 06:41:05 AM · #5 |
Let me see if I understand this...
If you have say 3 shots... one overexposed, one underexposed, and one somewhere in between, you could combine them to get one perfectly exposed shot. Or at least this is one way to use HDR.... right?
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02/11/2008 06:44:05 AM · #6 |
Just a couple more variations done to preserve what the brain compensated for, yet the camera could never capture:
From 4 separately exposed shots (2 to 8sec) and processed in CS2's HDR.
A single 10sec shot, changing and saving 5 different exposures of the same, then assembled in CS2's HDR.
HDR was developed to try and replicate what we "see" after the brain does it's post-processing and render it into a
natural scene with a full range of levels, without blowouts in the highlights and without loss of shadow detail. |
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02/11/2008 06:44:44 AM · #7 |
Then...could you say add a desaturated photo to this? Would that change the look somewhat, or would the other layers more or less chill out the desaturated one?
Yes, I could try and do this myself but I tend to ask more questions than the normal being!
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02/11/2008 06:45:56 AM · #8 |
Originally posted by Dantzr:
Let me see if I understand this...
If you have say 3 shots... one overexposed, one underexposed, and one somewhere in between, you could combine them to get one perfectly exposed shot. Or at least this is one way to use HDR.... right? |
That is what HDR is designed to do. Note that overexposure is the killer. Once detail is gone, no software will bring it back. |
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02/11/2008 07:08:13 AM · #9 |
HDR is not so much about choosing bits of several photos to suit the final result you want. It is very specifically about capturing extra highlight and shadow detail, and bringing that into the final image. HDR allows you to see detail in the deep dark shadows, and see detail in the bright highlights.
Dynamic range is a measure of how much range of brightness is recorded in an image. Most SLRs can record about 5 stops of brightness variation in the final image. So the brightest parts of the image are 5 stops brighter (32 times more light) than the darkest pixels. This is fine for many scenes, but sometimes scenes have more than 5 stops variation that you want to capture.
High dynamic range (HDR) uses multiple images of the same scene to record more information than your camera can capture in one shot. For example, if you shoot a photo, then reshoot underexposed by 1 stop down, you will lose shadow detail, but get an extra stop of highlight information, and another shot 1 stop overexposed will bring out 1 stop more detail in the shadows. HDR software will automatically combine these shots to give an overall image which records detail with 7 stops of light variation. You can expand this process as far as you need to, and get as many stops of HDR as you want, just by adding more images (assuming your subject is still long enough). You can then just squeeze the increased brightness range back into 255 brightness levels for display or printing, but this doesn't often give a good result. Instead, most HDR software incorporates 'tone-mapping' as the 2nd half of the process...
Tone-mapping is a process for automatically lightening the dark areas of an image and darkening the light areas, such that it produces a nice result with good visible detail in all areas, and the final result fits nicely back into the normal range of displayable tones.
Now, you can do tone-mapping without HDR, but you don't always get a good result, because there simply won't be as much highlight and shadow detail to retreive. Highlights will have been clipped, and shadow detail may be absent, or lost in noise. Similarly, you can do HDR without tone-mapping, but the result tends to look washed out. So, HDR and tone-mapping are almost always combined together, and the terms are often used interchangeably.
Hopefully this helps explain it a bit. :)
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02/11/2008 11:47:33 AM · #10 |
Originally posted by Brad:
Originally posted by Dantzr:
Let me see if I understand this...
If you have say 3 shots... one overexposed, one underexposed, and one somewhere in between, you could combine them to get one perfectly exposed shot. Or at least this is one way to use HDR.... right? |
That is what HDR is designed to do. Note that overexposure is the killer. Once detail is gone, no software will bring it back. |
Just as another example, here is a bracket sequence I did of one shot, converted into 4 exposures copies, opened each in Irfanview and re saved over itself to strip the EXIF prior to bringing them into CS2's HDR process. I typically shoot with exposure compensation around -1/3 to -1/2 stop allowing me the flexibility later to adjust, but without taking the chance of blowing out the highlights on the initial click.
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02/12/2008 12:25:32 AM · #11 |
Thank you so much for the great explanations. I had wondered how some photos seemed to come alive in detail more than others, now I have an idea how some of it comes to pass. Definitely have to hop to and learn Photoshop more so that maybe I can be able to do this myself. Thank you!!
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02/12/2008 12:54:08 AM · #12 |
From a previous post of mine when I shared the sources I found for information regarding HDR when researching it. Enjoy ... it is a whole new world.
For HDR conversion use the Local Adaptation method then open the Toning Curve and Histogram chart and drag the curve down to touch the leftmost point of the histogram. That is your starting point ... It should already look like a pretty decent image ... now put more points on the curve and play further with it ... ;)
The Equalize Histogram Method can sometimes give very quick and easy decent results with one click depending on the image.
Here are some further research resources for you all ...
//range.wordpress.com/2006/07/15/modern-hdr-photography-a-how-to-or-saturday-morning-relaxation/
//www.cambridgeincolour.com/tutorials/high-dynamic-range.htm
//www.popphoto.com/howto/3038/how-to-create-high-dynamic-range-images.html
//www.adidap.com/2006/11/25/photoshop-tutorial-hdr/
//www.naturescapes.net/072006/rh0706_1.htm
//stuckincustoms.com/?p=548
//www.luminous-landscape.com/tutorials/hdr.shtml
//dpchallenge.com/forum.php?action=read&FORUM_THREAD_ID=466859
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