Comments on: Musings on Dynamic Range, Bits and Stops http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/ Wed, 01 Sep 2010 02:32:25 -0400 http://wordpress.org/?v=2.8.4 hourly 1 By: The blog’s on fire this week | News and Views from Dave Wilson http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/comment-page-1/#comment-157 The blog’s on fire this week | News and Views from Dave Wilson Thu, 14 Jan 2010 04:30:39 +0000 http://blog.webartz.net/?p=708#comment-157 [...] by Dave Wilson on Jan.13, 2010, under Miscellaneous, Photography I just took a look at the blog traffic stats and was stunned to see that I’m receiving a huge number of visitors just now! Traffic in the last 24 hours was 20 times my daily average and 4 times higher than the previous daily maximum (which occured a week or so ago when Trey Ratcliff kindly posted a tweet pointing HDR enthusiasts at this post). [...] [...] by Dave Wilson on Jan.13, 2010, under Miscellaneous, Photography I just took a look at the blog traffic stats and was stunned to see that I’m receiving a huge number of visitors just now! Traffic in the last 24 hours was 20 times my daily average and 4 times higher than the previous daily maximum (which occured a week or so ago when Trey Ratcliff kindly posted a tweet pointing HDR enthusiasts at this post). [...]

]]> By: Dave Wilson http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/comment-page-1/#comment-145 Dave Wilson Wed, 30 Dec 2009 18:44:45 +0000 http://blog.webartz.net/?p=708#comment-145 Seriously, though, the point of using a wide bit format is that it allows you a lot more scope for numeric manipulation of the data without loss of quality before you map back to the output medium's bit depth. This is covered well in the book that I mention in the post. Seriously, though, the point of using a wide bit format is that it allows you a lot more scope for numeric manipulation of the data without loss of quality before you map back to the output medium’s bit depth. This is covered well in the book that I mention in the post.

]]> By: Dave Wilson http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/comment-page-1/#comment-144 Dave Wilson Wed, 30 Dec 2009 18:43:30 +0000 http://blog.webartz.net/?p=708#comment-144 Isn't that called "safety margin"? :-) Isn’t that called “safety margin”? :-)

]]> By: jimgoldstein http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/comment-page-1/#comment-143 jimgoldstein Wed, 30 Dec 2009 04:23:35 +0000 http://blog.webartz.net/?p=708#comment-143 Dave so what is the point of having a file that has the range you want, but lack the output medium to display it? Sounds like the photographic equivalent to speakers that go to 11 :) Dave so what is the point of having a file that has the range you want, but lack the output medium to display it? Sounds like the photographic equivalent to speakers that go to 11 :)

]]> By: Dave Wilson http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/comment-page-1/#comment-142 Dave Wilson Tue, 29 Dec 2009 18:26:52 +0000 http://blog.webartz.net/?p=708#comment-142 Over on Facebook, Bernard Ortiz pointed me at another discussion of this general topic. It's a lot more technical and accurate and may be of interest. You can find it <a href="http://www.luminous-landscape.com/forum/lofiversion/index.php/t21300.html" rel="nofollow">here</a>. Over on Facebook, Bernard Ortiz pointed me at another discussion of this general topic. It’s a lot more technical and accurate and may be of interest. You can find it here.

]]> By: dougp http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/comment-page-1/#comment-141 dougp Tue, 29 Dec 2009 18:13:13 +0000 http://blog.webartz.net/?p=708#comment-141 I have dug into my computer and located a matlab digest article on HDR, discussing some of the math involved in both creating an HDR image and the subsequent issue of tone mapping. The article can be located at http://www.mathworks.com/company/newsletters/digest/2008/july/hdri.html (sorry about the long URL, I haven't gotten any truncation application installed yet) I have dug into my computer and located a matlab digest article on HDR, discussing some of the math involved in both creating an HDR image and the subsequent issue of tone mapping. The article can be located at http://www.mathworks.com/company/newsletters/digest/2008/july/hdri.html (sorry about the long URL, I haven’t gotten any truncation application installed yet)

]]> By: Dave Wilson http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/comment-page-1/#comment-140 Dave Wilson Tue, 29 Dec 2009 12:30:38 +0000 http://blog.webartz.net/?p=708#comment-140 Jim, I agree, with one caveat - you are talking about the output of a tone mapping on an HDR image which is, by definition, no longer an HDR image but an image <i>derived</a> from an HDR source. An HDR image saved in an appropriate file format does have the capability of storing a far wider range of brightness than even our eyes can accomodate but one of the points I want to get across here is that it is unlikely that the image stored in that format will have a dynamic range anything like as high as the theoretical maximum allowed by the file format. The maximum dynamic range you are going to get in your (true) HDR file is limited by the camera sensor and the bracketing used to capture the constituent elements of the image. Once you tone map this, as you note, all bets are off and you are back in the 8bit, low dynamic range world again. Jim,

I agree, with one caveat – you are talking about the output of a tone mapping on an HDR image which is, by definition, no longer an HDR image but an image derived from an HDR source. An HDR image saved in an appropriate file format does have the capability of storing a far wider range of brightness than even our eyes can accomodate but one of the points I want to get across here is that it is unlikely that the image stored in that format will have a dynamic range anything like as high as the theoretical maximum allowed by the file format.

The maximum dynamic range you are going to get in your (true) HDR file is limited by the camera sensor and the bracketing used to capture the constituent elements of the image.

Once you tone map this, as you note, all bets are off and you are back in the 8bit, low dynamic range world again.

]]> By: jimgoldstein http://blog.webartz.net/2009/12/28/musings-on-dynamic-range-bits-and-stops/comment-page-1/#comment-137 jimgoldstein Tue, 29 Dec 2009 05:47:56 +0000 http://blog.webartz.net/?p=708#comment-137 A good explanation Dave, but photographers need to realize that HDR does not necessarily represent the tonal range of what we actually see. The marketing hype of HDR makes it out that it is. HDR can only display tonal range as good as the medium it's being shown on. On computer monitors that is going to be limited by the image files color space. As we know sRGB is hardly the most complete color space yet that is what we see most often online. In many ways HDR's promise of "equaling" what the human eye can see is a mirage. What HDR does offer is the ability to show more tonal range in a viewing environment that is by definition limited itself, just not as limited as the sensor capturing the image. Guy's tweeted point alluded to the process of how our brains piece together the tonal range of what we see and how we register it. I agree the parallel is there, but that doesn't mean the end product captures the same dynamic range. If you can represent the world outside of a shoe box with a particular technique, but still show it in a slightly larger shoe box what do you really gain? A good explanation Dave, but photographers need to realize that HDR does not necessarily represent the tonal range of what we actually see. The marketing hype of HDR makes it out that it is. HDR can only display tonal range as good as the medium it’s being shown on. On computer monitors that is going to be limited by the image files color space. As we know sRGB is hardly the most complete color space yet that is what we see most often online. In many ways HDR’s promise of “equaling” what the human eye can see is a mirage. What HDR does offer is the ability to show more tonal range in a viewing environment that is by definition limited itself, just not as limited as the sensor capturing the image.

Guy’s tweeted point alluded to the process of how our brains piece together the tonal range of what we see and how we register it. I agree the parallel is there, but that doesn’t mean the end product captures the same dynamic range. If you can represent the world outside of a shoe box with a particular technique, but still show it in a slightly larger shoe box what do you really gain?

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