Posted by Patrick Nixon on April 30, 2009 at 2:46 AM
Is it really necessary to resort to advanced formats (RAW or TIFF) or – moreover -- combine images taken at different exposures into high dynamic range (HDR) images to faithfully record the scenes we all seek to capture?
Under the best conditions, the most healthy and perceptive human eye can distinguish about a million (1048576=2 to the 20th or 20 EV or stops) different levels of luminance – and that requires time for adaptation to light or darkness and may vary depending upon individual sensitivity to color. The comparable value for a quick glance under bright sunlight is 131,072=2 to the 17th or 17 EV or stops.
The JPEG format is equivalent to 256=2 to the 8th or 7 EV (plus/minus 3 from pattern-metered exposure) EV or stops. At best, 14-bit RAW=16,384=2 to the 14th or 13 (plus/minus 6) EV or stops. The most common 12-bit RAW=4096=2 to the 12th or 11 (plus/minus 5) EV or stops. Theoretically the 14-RAW, 12-RAW and JPEG formats can record only 1/8th, 1/32nd and 1/512th of what the eye can typically see in daylight hours, respectively. Proving that even the best cameras can record only a small percentage of what the eye can see or distinguish.
The real question seems to be: How often do actual scenes exhibit more than the plus/minus 3 stops (7 stop range) of luminance we have come to accept with the JPEG format. Or the plus/minus 5 stop range equivalent to the 12-bit RAW format. What kinds of scenes typically exhibit a greater range? Sunsets? Green mountains or prairies against blue sky at mid-day? Or sandy beaches or snow against blue sky?
If the answer is “Not often.” there would seem to be little need to resort to the RAW format or HDR post-processing of bracketed exposures. Yet we have all seen stunning improvements using RAW or HDR in photo books.
What say you all? What kinds of scenes or light conditions typically demand bracketing, RAW, or HDR? Does anyone know of an authoritative reference setting forth the TYPICAL luminance range for different scenes or light conditions?
Posted by Paul DeCesare on April 30, 2009 at 12:32 PM
Patrick, nice calculation work!
If you head over to the PNWNP section, there's where you'll find photogs capturing images where the setting sun in Oregon at the Coast is screaming in, and the 16mm lens they're using that's only 4 inches above the foliage is still trying to capture detail in the FG. That alone widens the range > 3 stops. Then you add in the artistic touch where the current style is a FG that's about a stop brighter than it maybe should be, thus enforcing another 1-stop reduction in the sky (a look I personally like a LOT, here's an example). So you need SOMETHING to get it under all control. I've tried blending two RAW files that way with a canyon shot at sunset in Colorado, but the glare at the horizon makes it tough.
The solution? My favorite non-electrical photographic device: Singh-Ray 3-stop hard ND Grad filter.
One last thought: when some brightening is needed in an area of an image (even a whole FG), versions of Photoshop prior to CS4 had a Dodge tool that was destructive and ugly, so you did need to resort to blending/combining/folding/mutilating two images. CS4 has changed the game. The Dodge tool has tone preservation alogorithms that really work well, and you can hit a section harder than you ever could. SO, if you do have a section of an image that's a bit darker than you need, but the RAW has the data, it's much more retrievable now.
Hmmm, did I get off subject a little? Anyway, thanks for posting all that, it gets one thinking!
Whether it's necessary or not depends, I think, on what it is you're trying to achieve. If you're trying to maintain roughly the same sort of detail that your eye sees in anything other than a very narrowly toned scene, the answer is yes, it certainly is necessary. In addition to the examples you raised, another is flowing water in an area with plenty of dark rocks...even without any sun on the scene, frequently the decision has to be made to either blow the highlights (rarely if ever a good idea in a scene like this, IMO) or block up the shadows...or both...without resorting to some sort of image blending.
Personally, I like to do as little of this as possible. It's relatively time consuming to blend a shot, for one thing, and I've found that avoiding the stereotypical "HDR look" by resorting to full-blown HDR itself is particularly time consuming (though doable, as I've tried to demonstrate from time to time in this forum). I spent a great full day photographing at Big Walnut Preserve in central Indiana yesterday and one of the things that made it so great was that the shots I was after and the conditions (both weather and on the ground) made it possible to eschew multi-exposure in-the-field workflow entirely.
Still, if the shot I'm looking for requires a blend or HDR approach, that's what I do...and I do find that necessary a significant minority of the time.
I think these types of light conditions are actually pretty common, especially on days with direct sun of almost any sort. Control of overall brightness level is commonly needed, in my opinion, and there are occasions where it's the ONLY way to get a specific shot.
Hey Kerry - post some Big Walnut stuff! I'm curious to see what you got....I was in Brown County yesterday and the dogwoods were awesome.
For me I always shoot in RAW because I don't want to give up any amount of data the camera is capable of recording. Even if the scene might not require it, knowing I have a RAW capture is just a little piece of mind.
I must admit I find these high dynamic range conditions quite often shooting in nature. So often your faced with an exposure decision, highlights or shadows. Granted I don't do much blending, or HDR work, but knowing that I can if needed is a nice bonus. I usually try to work with a single capture as much as possible.
What would be the downside of shooting in RAW, outside of file size concerns?
One downside: out-of-date editing software. For several years I have been shooting RAW with a Nikon D70S and post processing using Photoshop CS2. Recently, I upgraded to a Nikon D300 -- only to find that my Photoshop CS2 would not read or process D300 RAW files. Even CS3 does not do so. At first I thought that I was going to have to upgrade to Photoshop CS4 (for me about $400) until I discovered Adobe's free DNG file converter. Using that software, I can first convert my D300 NEF files into DNG format and then read and edit in CS2 (purchased only 31 months ago). Editing proceeds fine, but this two-step process requires extra disk space for the DNG files about equal to that of the D300 NEF files.
Patrick, I'm quite sure D300 files can be processed using CS3's updated version of ACR. I have a friend in the Chicago area whose been doing so for quite some time.
My mistake then, although I've been told by mutiple commenters on the NPN Digital Imaging forum and also commenters on the Nikonians Landscape forum that CS3 will not process D300 RAW files. Can't say for certain myself one way or the other since I don't use CS3. Perhaps an issue to be searched out on the Adobe website.
The chronology of it doesn't make sense to me...the D300 came out in November of 2007. CS4 wasn't released until late September of 2008. It's beyond hard to believe that Adobe would basically not offer RAW support for such a popular camera for 10-odd months.
CS4 reads D300 NEF files fine. It is CS3 (and earlier) that might be a problem. One commenter on the Nikonian forum clearly stated that his copy of CS3 would not read/edit D300 RAW files until he downloaded an update of Camera RAW from Adobe. I suppose it depends upon when one purchased CS3.
Another commenter at Nikonians stated that when Adobe upodates, it only updates the version it is currently selling. Here is his post:
"Has Nikon changed the NEF file format..."
Although an answer was implied by several who provided responses, nobody directly answered this question. The answer is - yes, the NEF file format changed. Every change in camera sensor requires a new file format. Since the sensor's photosites are arranged basically in rows and columns, if you change the number of either the rows or columns (or both) you must also change the file format. So, whenever you change camera bodies you are almost certainly going to have a new raw file format to deal with. (Theoretically at least, if the manufacturer used the same sensor in two bodies they could also use the same raw file format - but I don't know any easy way to test for this.)
Unfortunately, when Adobe updates its camera raw plugin they do so for only the current versions of their software. So, if Photoshop CS3 was the current version when the D300 was released, Adobe updates the camera raw plugin for CS3, but not for CS2, CS or any earlier versions.
As you were able to discover, you can use Adobe's free DNG converter in a two-step process to first convert the files to Adobe's own DNG format, which can then be read by your Photoshop CS2."
CS4 reads D300 NEF files fine. It is CS3 (and earlier) that might be a problem. One commenter on the Nikonian forum clearly stated that his copy of CS3 would not read/edit D300 RAW files until he downloaded an update of Camera RAW from Adobe. I suppose it depends upon when one purchased CS3.
There you go. Adobe provides incremental updates to ACR on a regular basis, as new cameras are released and their RAW format changes are decoded. While the version of ACR that came with CS3 when it was originally released wouldn't support D300 files (since the camera didn't exist when CS3 was rolled out, ACR was updated several times in the final 10 months of CS3's existence after the D300 was available and any of those versions, fully compatible with CS3, support D300 files.
It's absolutely correct that Adobe stops providing ACR support for previous versions of PS once a new version is released so any camera that's come out since last September (the D3X, for instance) wouldn't have RAW support within the ACR module attached to CS3. That's where the DNG converter workflow option, the purchase of another RAW converter (e.g. Capture NX2) or upgrading to CS4 comes in.
But updating to the latest ACR module that is compatible with CS3 absolutely will allow you to work on D300 NEF files.
Discussion
11 repliesUnder the best conditions, the most healthy and perceptive human eye can distinguish about a million (1048576=2 to the 20th or 20 EV or stops) different levels of luminance – and that requires time for adaptation to light or darkness and may vary depending upon individual sensitivity to color. The comparable value for a quick glance under bright sunlight is 131,072=2 to the 17th or 17 EV or stops.
The JPEG format is equivalent to 256=2 to the 8th or 7 EV (plus/minus 3 from pattern-metered exposure) EV or stops. At best, 14-bit RAW=16,384=2 to the 14th or 13 (plus/minus 6) EV or stops. The most common 12-bit RAW=4096=2 to the 12th or 11 (plus/minus 5) EV or stops. Theoretically the 14-RAW, 12-RAW and JPEG formats can record only 1/8th, 1/32nd and 1/512th of what the eye can typically see in daylight hours, respectively. Proving that even the best cameras can record only a small percentage of what the eye can see or distinguish.
The real question seems to be: How often do actual scenes exhibit more than the plus/minus 3 stops (7 stop range) of luminance we have come to accept with the JPEG format. Or the plus/minus 5 stop range equivalent to the 12-bit RAW format. What kinds of scenes typically exhibit a greater range? Sunsets? Green mountains or prairies against blue sky at mid-day? Or sandy beaches or snow against blue sky?
If the answer is “Not often.” there would seem to be little need to resort to the RAW format or HDR post-processing of bracketed exposures. Yet we have all seen stunning improvements using RAW or HDR in photo books.
What say you all? What kinds of scenes or light conditions typically demand bracketing, RAW, or HDR? Does anyone know of an authoritative reference setting forth the TYPICAL luminance range for different scenes or light conditions?
If you head over to the PNWNP section, there's where you'll find photogs capturing images where the setting sun in Oregon at the Coast is screaming in, and the 16mm lens they're using that's only 4 inches above the foliage is still trying to capture detail in the FG. That alone widens the range > 3 stops. Then you add in the artistic touch where the current style is a FG that's about a stop brighter than it maybe should be, thus enforcing another 1-stop reduction in the sky (a look I personally like a LOT, here's an example). So you need SOMETHING to get it under all control. I've tried blending two RAW files that way with a canyon shot at sunset in Colorado, but the glare at the horizon makes it tough.
The solution? My favorite non-electrical photographic device: Singh-Ray 3-stop hard ND Grad filter.
One last thought: when some brightening is needed in an area of an image (even a whole FG), versions of Photoshop prior to CS4 had a Dodge tool that was destructive and ugly, so you did need to resort to blending/combining/folding/mutilating two images. CS4 has changed the game. The Dodge tool has tone preservation alogorithms that really work well, and you can hit a section harder than you ever could. SO, if you do have a section of an image that's a bit darker than you need, but the RAW has the data, it's much more retrievable now.
Hmmm, did I get off subject a little? Anyway, thanks for posting all that, it gets one thinking!
Personally, I like to do as little of this as possible. It's relatively time consuming to blend a shot, for one thing, and I've found that avoiding the stereotypical "HDR look" by resorting to full-blown HDR itself is particularly time consuming (though doable, as I've tried to demonstrate from time to time in this forum). I spent a great full day photographing at Big Walnut Preserve in central Indiana yesterday and one of the things that made it so great was that the shots I was after and the conditions (both weather and on the ground) made it possible to eschew multi-exposure in-the-field workflow entirely.
Still, if the shot I'm looking for requires a blend or HDR approach, that's what I do...and I do find that necessary a significant minority of the time.
Hey Kerry - post some Big Walnut stuff! I'm curious to see what you got....I was in Brown County yesterday and the dogwoods were awesome.
CJ
For me I always shoot in RAW because I don't want to give up any amount of data the camera is capable of recording. Even if the scene might not require it, knowing I have a RAW capture is just a little piece of mind.
I must admit I find these high dynamic range conditions quite often shooting in nature. So often your faced with an exposure decision, highlights or shadows. Granted I don't do much blending, or HDR work, but knowing that I can if needed is a nice bonus. I usually try to work with a single capture as much as possible.
What would be the downside of shooting in RAW, outside of file size concerns?
For some people (not me), workflow is an issue.
Another commenter at Nikonians stated that when Adobe upodates, it only updates the version it is currently selling. Here is his post:
"Has Nikon changed the NEF file format..."
Although an answer was implied by several who provided responses, nobody directly answered this question. The answer is - yes, the NEF file format changed. Every change in camera sensor requires a new file format. Since the sensor's photosites are arranged basically in rows and columns, if you change the number of either the rows or columns (or both) you must also change the file format. So, whenever you change camera bodies you are almost certainly going to have a new raw file format to deal with. (Theoretically at least, if the manufacturer used the same sensor in two bodies they could also use the same raw file format - but I don't know any easy way to test for this.)
Unfortunately, when Adobe updates its camera raw plugin they do so for only the current versions of their software. So, if Photoshop CS3 was the current version when the D300 was released, Adobe updates the camera raw plugin for CS3, but not for CS2, CS or any earlier versions.
As you were able to discover, you can use Adobe's free DNG converter in a two-step process to first convert the files to Adobe's own DNG format, which can then be read by your Photoshop CS2."
There you go. Adobe provides incremental updates to ACR on a regular basis, as new cameras are released and their RAW format changes are decoded. While the version of ACR that came with CS3 when it was originally released wouldn't support D300 files (since the camera didn't exist when CS3 was rolled out, ACR was updated several times in the final 10 months of CS3's existence after the D300 was available and any of those versions, fully compatible with CS3, support D300 files.
It's absolutely correct that Adobe stops providing ACR support for previous versions of PS once a new version is released so any camera that's come out since last September (the D3X, for instance) wouldn't have RAW support within the ACR module attached to CS3. That's where the DNG converter workflow option, the purchase of another RAW converter (e.g. Capture NX2) or upgrading to CS4 comes in.
But updating to the latest ACR module that is compatible with CS3 absolutely will allow you to work on D300 NEF files.