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Author Topic: Is the 16bit advantage a bit of a myth?  (Read 16041 times)
Panopeeper
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« Reply #60 on: February 11, 2008, 01:47:49 PM »
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I think Panokeeper's point was...

You understood my post (as opposed to the the addresse). Thanks for saving it to me.
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Gabor
jbrembat
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« Reply #61 on: February 11, 2008, 01:52:32 PM »
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Anyone doing 8 bit HDR?
[a href=\"index.php?act=findpost&pid=173966\"][{POST_SNAPBACK}][/a]
Yes I do.

HDR start to be a field of research in 1995,Mann and Picard published
“On Being ‘Undigital’ with Digital Cameras: Extending Dynamic Range
by Combining Differently Exposed Pictures,”  

In SIGGRAPH 97 Debevec and Malik published "Recovering High Dynamic Range Radiance Maps from Photographs"

Their work was for jpg photos.

Hdr may be performed on jpg images.
Recovery of radiance maps is more simple for raw, but processing jpg image you can get  good results.

Jacopo
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Gordon Buck
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« Reply #62 on: February 11, 2008, 02:16:45 PM »
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Hdr may be performed on jpg images.

[a href=\"index.php?act=findpost&pid=174008\"][{POST_SNAPBACK}][/a]

When I think of "HDR", I'm thinking primarily of 32 bit images assembled from lesser bit images.  The post processing of those 32 bit images sometimes includes "tone mapping" which I think of as a means of squeezing that 32 bit assembly into a 16 bit and eventually into an 8 bit image for display or printing.

What I was attempting to point out -- but apparently missed the mark -- was that if there is no advantage to 16 bit images then how can there be an advantage to 32 bit images?  Therefore, the 32 bit image HDR must be an even more grandiose conspiracy than the 16 bit marketing ploy.  (Getting lost in the sarcasm again, it  seems to me that there are advantages to each.)

I've tinkered with HDR and sometimes like it, sometimes not.  But since you've worked with HDR and jpg, perhaps you have an answer for a question that I've been meaning to investigate but haven't as yet.  In all sincerity, when assembling an HDR file from jpg components, is it necessary to use more jpg files than would have been necessary if raw files had been used?
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mistybreeze
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« Reply #63 on: February 11, 2008, 02:19:52 PM »
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The capture resolution determines the initial file size
Of course, and I apologize if it wasn't clear that I understood this. I shouldn't assume that everyone knows what medium format camera backs these artists are using to produce their art. And truth be told, some continue to shoot in large format film and then drum scan. Capture resolutions may vary but the psychology behind big numbers does not, especially if money is no object.
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jbrembat
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« Reply #64 on: February 11, 2008, 03:22:52 PM »
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When I think of "HDR", I'm thinking primarily of 32 bit images assembled from lesser bit images.  The post processing of those 32 bit images sometimes includes "tone mapping" which I think of as a means of squeezing that 32 bit assembly into a 16 bit and eventually into an 8 bit image for display or printing.

What I was attempting to point out -- but apparently missed the mark -- was that if there is no advantage to 16 bit images then how can there be an advantage to 32 bit images?  Therefore, the 32 bit image HDR must be an even more grandiose conspiracy than the 16 bit marketing ploy.  (Getting lost in the sarcasm again, it  seems to me that there are advantages to each.)
I've tinkered with HDR and sometimes like it, sometimes not.  But since you've open shadow but no more.
worked with HDR and jpg, perhaps you have an answer for a question that I've been meaning to investigate but haven't as yet.  In all sincerity, when assembling an HDR file from jpg components, is it necessary to use more jpg files than would have been necessary if raw files had been used?
[{POST_SNAPBACK}][/a]
gordonsbuck,
 tonemapping is to compress the HDR into LDR image. Devices, monitors and printers are LDR.
The compression must be performed trying to preserve the generl appearance.

HDR is recovered from  multi-exposures using floating point, not fixed point (16 bit are integers).
After tonemapping,  the images are good for monitor and printer.
There is not any real advantage to make them 16 bit (LDR images are images similar to camera shots, developed to be useful).

For the last answer:
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In all sincerity, when assembling an HDR file from jpg components, is it necessary to use more jpg files than would have been necessary if raw files had been used?
If you start with a single jpg you can't do HDR. You can use shadows/highlights tools.
For HDR you can use multiple jpg shots or raw or a single raw developed at differt exposures.
The advantage of single raw is that the images are perfectly registered and moving objects are not a problem.
But, the HDR is limited by the camera. If you have a huge contrast in the scene you can't acquire it.

I wrote a short article on HDR at my website:
[a href=\"http://www.photoresampling.com/index_eng.php]http://www.photoresampling.com/index_eng.php[/url]
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pss
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« Reply #65 on: February 11, 2008, 05:23:05 PM »
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Of course, and I apologize if it wasn't clear that I understood this. I shouldn't assume that everyone knows what medium format camera backs these artists are using to produce their art. And truth be told, some continue to shoot in large format film and then drum scan. Capture resolutions may vary but the psychology behind big numbers does not, especially if money is no object.
[a href=\"index.php?act=findpost&pid=174021\"][{POST_SNAPBACK}][/a]

actually afaik annie shoots with canons:) which are not 16bit anyway...
but you are absolutely correct...even simple retouching (not adjustments) easily ends up as a 1gb+ PS file....
and why would anyone throw away detail or data? of course everybody shoots raw....why would you not want the best for the one or few files that actually end up being used? does not matter if they end up in mags or at the MOMA...or on your wall at home....
i work in 16bit only, i could not care less about the technical details but i see the difference in color and gradations (skys!)....just not worth "saving" a couple of GBs....
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Panopeeper
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« Reply #66 on: February 11, 2008, 05:50:57 PM »
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but you are absolutely correct...even simple retouching (not adjustments) easily ends up as a 1gb+ PS file....

It is not a great achievement to create a large Photoshop file. The achievement is to explain, why not using compressed TIFF, which is much smaller.
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Gabor
Ray
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« Reply #67 on: February 11, 2008, 10:02:47 PM »
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The problem is that most people are not going to take the time and trouble to make prints from 8 bit and 16 bit processrd files to see if and when there's a noticeable benefit to using the extra resources required for 16 bit.

There is an assumption that, if you can't see it on the monitor at 200% then you won't see it in the print. In fact, I think most people's experience is that stuff you can see on the monitor doesn't always get translated to the print. I believe this is because a view of a detail on the monitor at just 100% often represents a print size much larger than what's printed.

When CS3 was released, I was at first undecided whether to pay the extra money for the CS3E version. After experimenting with the stacking options in CS3E, I decided it was worth the extra money and I set out on my recent trip a few months ago with a copy of CS3E on my laptop.

One experiment I did was to photograph my hotel room with my 5D without using flash. To get maximum DoF, I used f16 which at ISO 3200 allowed for a shutter speed of only 1/20th second. The lens was the Sigma 15-30 which doesn't have IS, so the image is understandably not particularly sharp. However, never mind! The purpose of the experiment was to see how CS3E's stacking options and auto-alignment feature would handle a series of hand-held shots taken in continuous mode, bearing in mind the slow frame rate of the 5D.

I took a burst of 7 shots. There's some slight movement between frames as one would expect, but CS3's auto-alignment seemed to handle that perfectly.

What I couldn't do, however, was stack those images in 16 bit mode. My laptop didn't have the resources. 2Gb of RAM is apparently not enough. I had to convert all 7 images to 8 bit tiffs before stacking.

Now that I'm back in Australia, and after reading this thread, I thought it might be interesting to stack those same images again in 16 bit mode using my desktop computer, and compare.

Below are 100% crops comparing, from left to right, 8-bits stacked, 16-bits stacked and a single unstacked image showing the noise difference, followed by the full scene.

[attachment=5100:attachment]  [attachment=5101:attachment]
« Last Edit: February 11, 2008, 10:04:13 PM by Ray » Logged
JeffKohn
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« Reply #68 on: February 11, 2008, 10:30:55 PM »
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It is not a great achievement to create a large Photoshop file. The achievement is to explain, why not using compressed TIFF, which is much smaller.
[a href=\"index.php?act=findpost&pid=174073\"][{POST_SNAPBACK}][/a]
In my experience the difference between  a compressed TIFF and a PSD is less than 10%, but the TIFF takes much longer to save. So I tend to use PSD's unless I need to edit a file in Lightzone or Photomatix.
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Panopeeper
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« Reply #69 on: February 11, 2008, 11:18:47 PM »
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In my experience the difference between  a compressed TIFF and a PSD is less than 10%, but the TIFF takes much longer to save

PSD adopts run length encoding. ZIP is the best with TIFF, though it requires the most computing. The result depends on the actual data.

Once I compared files of several hundred MB size, and in some cases found smaller difference than 10%; in other cases, the difference was larger.

Now I made a comparison with 16 bit and the difference was less than 10%. Then I changed the file in 8 bit mode, and TIFF with ZIP became HALF the size of the PSD.
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Gabor
JeffKohn
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« Reply #70 on: February 12, 2008, 11:58:22 AM »
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PSD adopts run length encoding. ZIP is the best with TIFF, though it requires the most computing. The result depends on the actual data.

Once I compared files of several hundred MB size, and in some cases found smaller difference than 10%; in other cases, the difference was larger.

Now I made a comparison with 16 bit and the difference was less than 10%. Then I changed the file in 8 bit mode, and TIFF with ZIP became HALF the size of the PSD.
[a href=\"index.php?act=findpost&pid=174135\"][{POST_SNAPBACK}][/a]
Interesting. I almost always save in 16-bit so that would explain why I didn't see much difference.
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