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09-24-2009, 08:56 AM   #16
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but does it look good in camera when you are doing the tone mapping? i think i would much prefer the tone mapping be done PP because you can explore the subtleties of a photo better on a 22 inch screen than a 2.7 inch...you know? i use the k20 so the tone mapping step isnt an option - but i think id always do it PP.

09-24-2009, 09:39 AM   #17
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QuoteOriginally posted by T_MB Quote
Sorry for beating a dead horse, but now I am confused. I thought the multi-exposure function allowed you to exposure bracket a shot -1, 0, +1 and then overlaid all three (or however many you took) images on top of one another. --Essentially doing in camera what you can do in photoshop.

Assuming each of those three shots correctly exposes the various parts of a scene--how is that different than HDR?
No offence intended but yes you are confused.

HDR is essentually as you discussed, 3 or more shots each exposed correctly for a portion of the scene. and added together using masks for the incorrect exposure areas.

Multiple exposure is not the same thing, it is multiple shots at 1/n (n being number of shots) of the correct exposure, with the results added so that the end image also now has the correct exposure. For Multiple exposure, the camera does not reset the light captured by the sensor, it jsut keeps adding more to the sensor until you are finished shooting. As a result, burnt highlights will be burnt highlights and dark shadows will be dark shadows.


Someone else commented about the extended dynamic range, which seems to be different, and compresses the data a little more in the central portion of the histogram. i.e. it is ultra reduced contrast. It compresses the range from 25-230 in the histogram from about 45 greyscale per stop (in this range) to about 30 greyscale per stop, leaving more room for highlight and shadow.
09-24-2009, 12:11 PM   #18
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QuoteOriginally posted by Lowell Goudge Quote
HDR is essentually as you discussed, 3 or more shots each exposed correctly for a portion of the scene. and added together using masks for the incorrect exposure areas.
Be careful not to confuse further! (Or throw out #'s as smoke... )
General-purpose HDR does not use masks, in fact "true" HDR (think Radiance and OpenEXR files, not the crap on Flickr tagged "HDR") does not discard any of the data until the image is tonemapped into an LDR image (which also does not involve masking).

That said, the K-7 uses an interesting type of exposure "blending" to create its "HDR capture mode" output images (which, again, are LDR not HDR), and these may have masks based on the exposure, contrast, and saturation of individual pixels or small groups of them. Ah, but it isn't HDR ouput, nor is it an HDR image that has been tonemapped. It's 3 exposures that have been blended together based on these varying criteria, with a function name that (apparently) confuses things further. So I guess you could say you are right when using the misnomer that Pentax has applied to the process.

If I sound grumpy, it's because I agree with this guy (who, like me, isn't new to this and isn't on Flickr): Flickr HDR
09-24-2009, 02:17 PM   #19
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Wow. Lots of useful info here. I clearly have much to learn about this process.

However, at the risk of stiring up a hornet's nest and further demonstrating my ignorance....I don't really understand what all the fuss is about in that article. I understand the author's main point--that HDR software is being used to create images it wasn't intended to create.....but so what?

Some people like the so-called "HDR-look"; others don't. Personally, I like some and dislike others. I don't really care what tools an artist uses so long as the image is pleasing. I don't care a hill of beans if someone produces a certain look by using filters, photoshop, or other techniques. The only problem I see, and as this thread demonstrates, is one of nomenclature.--People are confusing the "look" of images "incorrectly processed" or "over processed" with HDR software with the software itself, such that people like me are confusing results with process.

..please feel free to flame my newbie, know-nothing, uninformed opinions

09-24-2009, 05:29 PM   #20
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Thought I'd try the Multiple Exposue mode on my K20, but I'm having issues.

When I open the menu I can see and select the Multi-exposure option, I can set theet number of shots and hit OK which takes me back to the main menu where the Multi-exposure shows "5 times"

I then hit OK and the menu display goes off.

If I open the Menu again, Muilt-Exposure now shows "OFF"

It doesn't matter how I exit the Menu (either via OK, or Menu button) The setting just doesn't seem to stick.

I've tried this in multiple modes. In Green, it won't let me access Multi-exposure option, but in all others, it let's me set it, but it won't retain it.

Can anyone spot what I'm doing wrong here? Is there some other setting involved?

Thanks in advance for your help.

regards,
-tom
09-24-2009, 05:34 PM   #21
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This is more confusing than I thought! Thanks for all the info. It did appear to me that using 9 multi exposures gave a better exposed image with better dynamic range than taking a single shot, but I will go back and look at the images again to see if that is true.
09-24-2009, 05:45 PM   #22
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QuoteOriginally posted by ozlizard Quote
This is more confusing than I thought! Thanks for all the info. It did appear to me that using 9 multi exposures gave a better exposed image with better dynamic range than taking a single shot, but I will go back and look at the images again to see if that is true.
One good use of multiple exposure option is to slow down the shutter when you don't have the ND filter with you; this will create a slow shutter effect in the combined shot.
09-24-2009, 06:09 PM   #23
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QuoteOriginally posted by panoguy Quote
It's 3 exposures that have been blended together based on these varying criteria, with a function name that (apparently) confuses things further.
Well, the internal firmware function name is "CombineHighDynamicRangeImage" which is rather neutral and doesn't exhibit the algorithm used

But the lack of further firmware symbols suggests that they do a blending (single pass) rather than hdr + tone map (two passes). Just like you suggested.

09-24-2009, 07:19 PM   #24
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I have had another look at the images, luckily I had taken a single shot as well as a multiple exposure of each scene and it seems that there is no difference to the exposure. Apart from the effect on water and clouds (which I like) what purpose does this funtion fulfill and what was it intended to fulfull?
09-24-2009, 09:20 PM   #25
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QuoteOriginally posted by ozlizard Quote
I have had another look at the images, luckily I had taken a single shot as well as a multiple exposure of each scene and it seems that there is no difference to the exposure. Apart from the effect on water and clouds (which I like) what purpose does this funtion fulfill and what was it intended to fulfull?
In the daytime you may not notice much differnence, but at dusk or in other low-light situations you should notice less noise.

Dan.
09-24-2009, 10:05 PM   #26
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QuoteQuote:
In the daytime you may not notice much differnence, but at dusk or in other low-light situations you should notice less noise
That would be as Mithrandir explained about the way the sensitivity is split up between the shots, not sure I understand all that but it seems to be a good feature.
Is there any way of storing or recording the settings in mutiple exposure so you don't have to manually go into the menu and set it up for each set of shots?
09-24-2009, 10:19 PM   #27
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Not that I'm aware of. It would require a firmware hack.
09-24-2009, 10:33 PM   #28
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Thanks dosdan when will you have that hack ready? LOL
09-25-2009, 10:10 PM   #29
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tpeace.....I had the same experience. Basically, once you set the settings, you must then trigger the shutter the number of times you indicated (i.e. 5 times in your example). If you hit the menu it essentually wipes out the setting and assumes you did not want to take the multiple exposures. If it works correctly, you should be able to watch the counter take one shot away on your counter and then add it back to indicate it is writing to the previous image. Once you shoot the five shots, it then resumes normal "single exposure" shots. You must set this setting for each time you want to use the technique. At least that has been my experience so far.
09-26-2009, 09:28 AM   #30
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QuoteOriginally posted by jwebberfb Quote
tpeace.....I had the same experience. Basically, once you set the settings, you must then trigger the shutter the number of times you indicated (i.e. 5 times in your example). If you hit the menu it essentually wipes out the setting and assumes you did not want to take the multiple exposures. If it works correctly, you should be able to watch the counter take one shot away on your counter and then add it back to indicate it is writing to the previous image. Once you shoot the five shots, it then resumes normal "single exposure" shots. You must set this setting for each time you want to use the technique. At least that has been my experience so far.

Thanks JW, This works!

regards-t
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