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Author Topic: Using HDR tone mapping for ordinary images  (Read 14956 times)
ErikKaffehr
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« on: December 06, 2011, 11:35:37 PM »
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Hi,

I started on writing a small article on using HDR tone mapping on ordinary non HDR images. I have most of the images in place, but will fill in more text.

http://echophoto.dnsalias.net/ekr/index.php/photoarticles/61-hdr-tone-mapping-on-ordinary-image

The image may be slightly psychedelic, but the ideas may be useful.

Best regards
Erik
« Last Edit: December 09, 2011, 04:09:07 AM by ErikKaffehr » Logged

Jack Varney
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« Reply #1 on: December 07, 2011, 05:44:55 PM »
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A question for discussion. Why is tone mapping on this image (or any other) any different than using the myriad of tone and color controls available in Photoshop, Lightroom and Capture One? It seems to me that HDR is one more tool for the photographer to deliver her/his message, feeling or emotion.

Nice job Eric.
« Last Edit: December 07, 2011, 06:46:30 PM by Jack Varney » Logged

Jack Varney
ErikKaffehr
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« Reply #2 on: December 08, 2011, 01:16:17 AM »
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Hi,

Best info I have found as for now, regarding "Local Adaption":

"This is the most flexible method and probably the one which is of most use to photographers. Unlike the other three methods, this one changes how much it brightens or darkens regions on a per-pixel basis (similar to local contrast enhancement). This has the effect of tricking the eye into thinking that the image has more contrast, which is often critical in contrast-deprived HDR images. This method also allows changing the tonal curve to better suit the image."

Quotation from this article: http://www.cambridgeincolour.com/tutorials/high-dynamic-range.htm

Best regards
Erik

A question for discussion. Why is tone mapping on this image (or any other) any different than using the myriad of tone and color controls available in Photoshop, Lightroom and Capture One? It seems to me that HDR is one more tool for the photographer to deliver her/his message, feeling or emotion.

Nice job Eric.
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madmanchan
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« Reply #3 on: December 08, 2011, 02:15:00 AM »
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Effectively it is (local) dodging and burning.
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stamper
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« Reply #4 on: December 08, 2011, 03:17:29 AM »
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From my limited experience most images that have had HDR techniques  applied to them didn't - from a technical sense - need them. As previous posters stated there are simpler techniques available.  I have posted images on Flickr that viewers thought had been through HDR but was only a little aggressive PS. This is where most advocates of HDR go amiss. They choose images that don't need HDR and the technique as a whole gets panned.
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ErikKaffehr
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« Reply #5 on: December 08, 2011, 05:41:15 AM »
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Hi!

The problem I have with this image that it is very boring without the techniques described. If you happen to read the article you may understand the issue a little better. The idea with the article is to share experience, someone may find it useful.

Best regards
Erik


From my limited experience most images that have had HDR techniques  applied to them didn't - from a technical sense - need them. As previous posters stated there are simpler techniques available.  I have posted images on Flickr that viewers thought had been through HDR but was only a little aggressive PS. This is where most advocates of HDR go amiss. They choose images that don't need HDR and the technique as a whole gets panned.
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hjulenissen
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« Reply #6 on: December 08, 2011, 12:42:00 PM »
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A question for discussion. Why is tone mapping on this image (or any other) any different than using the myriad of tone and color controls available in Photoshop, Lightroom and Capture One? It seems to me that HDR is one more tool for the photographer to deliver her/his message, feeling or emotion.

Nice job Eric.
I think it is useful to distinguish between A)the synthesis of exposure bracketed images, and B) the application of fancy tonemapping to render the HDR source into LDR. Most people mean both A) and B) when saying HDR, and that makes it more difficult to discuss things like this.

I see no reason why e.g. Lightroom cannot offer tonemapping-like controls for HDR and single-shots alike. In fact, I would be surprised if it does not happen soon. The main (only?) difference is that you can "go further" if the source is a large series of brackets, if the scene is demanding.

As have been said, tonemapping is generally local (as opposed to global), non-linear and adaptive. But it is perhaps fair to say that tonemapping algorithms tries to automate what photography editors "with good taste" does when dodging and burning: lift out interesting details from the shadows, clamp down seemingly clipped areas, maximize the visible information _while_ keeping the look somewhat natural. My take on this is that regular LDR images shown on LDR displays with little curves/levels applied is actually a special kind of global tonemapping: clipping the shadows and highlights (if present). It is a very intuitive way to do it, and one that we have been historically brought up on, but nothing warrants a fundamentalistic view that it is always more "realistic", while any other tonemapping operators are "artificial".

Are there any cases where the scene is e.g. 100:1 DR, and the display/paper is 100:1 DR, but we may want to artificially limit the DR to something less for artistic reasons? If such cases can be argued for, then we have a very similar case to radio stations that limit 16-bit CDs to 5-6 bits of effective DR prior to transmitting them on a 16-bit capable digital radio channel.

-h
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madmanchan
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« Reply #7 on: December 08, 2011, 02:30:54 PM »
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Lr already does offer such tools.  For example, Fill Light and Clarity work on the whole image, but are locally adaptive to the scene content.  There are also local tools (e.g., local Exposure) for local tuning.  All of these are really tone mapping or "tone management" tools. 
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hjulenissen
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« Reply #8 on: December 08, 2011, 04:02:16 PM »
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Lr already does offer such tools.  For example, Fill Light and Clarity work on the whole image, but are locally adaptive to the scene content.  There are also local tools (e.g., local Exposure) for local tuning.  All of these are really tone mapping or "tone management" tools. 
Yes, you are right. And by my own arguments, even curves and levels found in most image editors is similar to the tonemapping operators found in HDR applications. But there seems to be significant differences in parameters, feedback and end-results?

But I dont think there is a meaningful way to apply them to "raw" bracketed exposures? One is forced to use an external application to synthesize the exposures and process it into LDR (or at least some manageable intermediate format).

-h
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ErikKaffehr
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« Reply #9 on: December 08, 2011, 11:38:42 PM »
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Hi,

I don't think I could achieve the same effect using local adjustments, simply because I'm not good enough at using local adjustments.

The idea with the article was more to illustrate that HDR mapping can be used in this way.

The image below is made from a single exposure, just using Lightroom tools:


While this one is from three exposures at two EV apart using "Merge to HDR" in CS5:


The image on top is from the darkest exposure in the series.

Best regards
Erik

Lr already does offer such tools.  For example, Fill Light and Clarity work on the whole image, but are locally adaptive to the scene content.  There are also local tools (e.g., local Exposure) for local tuning.  All of these are really tone mapping or "tone management" tools.  
« Last Edit: December 08, 2011, 11:46:11 PM by ErikKaffehr » Logged

kikashi
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« Reply #10 on: December 09, 2011, 02:57:00 AM »
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Erik,

I'm puzzled by the fact that the clouds are so much better-defined in the second image, made from multiple exposures.

Jeremy
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stamper
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« Reply #11 on: December 09, 2011, 03:28:04 AM »
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If Erik was to go back and start from scratch and re do the two images and then inspect them he would - I am confident - find differences between all four. This is the Achilles heel of his original post. The isn't a definitive way of processing images.
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ErikKaffehr
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« Reply #12 on: December 09, 2011, 04:03:54 AM »
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Hi,

The first image is made using LR controls from the "-2 EV" image. The second one is using "Merge to HDR" with "Local Adaption" from three exposures in CS5.

So the two images are produced by very different means. The first image is produced by using graduated filter and extensive adaption of clarity on the clouds.

Best regards
Erik


Erik,

I'm puzzled by the fact that the clouds are so much better-defined in the second image, made from multiple exposures.

Jeremy
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ErikKaffehr
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« Reply #13 on: December 09, 2011, 04:06:35 AM »
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Hi,

I never said that there is one definitive way to process images. The original article just described one way to utilize a couple of methods.

This was the original posting:
"Hi,

I started on writing a small article on using HDR tone mapping on ordinary non HDR images. I have most of the images in place, but will fill in more text.

http://echophoto.dnsalias.net/ekr/index.php/photoarticles/61-hdr-tone-mapping-on-ordinary-image

The image may be slightly psychedelic, but the ideas may be useful."
Best regards
Erik

If Erik was to go back and start from scratch and re do the two images and then inspect them he would - I am confident - find differences between all four. This is the Achilles heel of his original post. The isn't a definitive way of processing images.
« Last Edit: December 09, 2011, 04:08:41 AM by ErikKaffehr » Logged

stamper
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« Reply #14 on: December 09, 2011, 04:45:37 AM »
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Eric I am not criticising your effort to relate something but HDR is a controversial subject and I think you won't win over many people to your way of thinking? The subject has been debated to death and possibly/probably been documented more extensively. You haven't chosen a little known technique to throw illumination on. I also suspect that - not me - there are members here who know/think they have better knowledge on the subject. Good luck.
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Peter_DL
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« Reply #15 on: December 31, 2011, 01:07:20 PM »
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... using HDR tone mapping on ordinary non HDR images.

+1:  Expanding the dynamic range of a single RAW file
 
 
Lr already does offer such tools.  For example, Fill Light and Clarity work on the whole image, but are locally adaptive to the scene content...

No mentioning of Recovery ...

--
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madmanchan
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« Reply #16 on: January 02, 2012, 09:30:22 AM »
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I was just mentioning examples, not meant to be exhaustive.   Wink
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leuallen
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« Reply #17 on: January 02, 2012, 09:26:00 PM »
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I recently discovered SNS-HDR Pro. I have most of the popular HDR programs or have at least tried them. SNS is by far my favorite due to its masking capabilities. I had a single exposure image which I could not easily get the effect I wanted using LR and PS so I decided to split it into two exposures, shadows vs highlights, and import it into SNS to work on it. I got very good results.

Masking in SNS has one very powerful feature called 'Intelligent selection'. Yes it is intelligent and works very well, a surprise considering all the disappointments one encounters with market speak about all the new 'magic' tools. It works similar to the auto masking available for the local brush in LR, except that this really works. I have noticed no halos using these masks.

If I were processing Erik's image here is how I would approach it:

Low exposure and high exposure images imported into SNS.

Use setting Neutral or Natural. Adjust exposure slider and highlight recovery and other sliders to get best image.

Create first mask. Use intelligent selection to select rocks. One click of the paint bucket tool would probably work in this case. In cases where you get to much selection you can try right clicking on the unwanted area if it is significantly different than the area you want This will remove that area from the selection. Or you can use the brush with intelligent selection off and paint the area out holding the right button down. Or you can invert the mask and paint away the offending areas normally-this works good because you can see the bad areas more easily on the green overlay. Anyway there are lots of ways to easily get a good mask. This is remarkable to me considering that SNS is still in its infancy and is still missing lots of features. For example, you cannot change the brush size (oft requested), you must enlarge the view to get the effect of a smaller brush. I consider the masking outstanding and I am a intensive student of masking techniques.

With the first mask made, make a copy and invert it. We now have masks for the sky and the rocks. You can work each mask separately, changing exposure, contrast, local contrast, details, saturation, black points, color temp... almost everything. I would play with the sky area by playing with the sliders to see their effect. Midtone contrast, microdetails, and microcontast would probably have the most effect.

Then switch to the rocks mask and do the same.

Probably have a decent image by now but there is more that can be done. Create a new mask and use intelligent selection to select the blues of the sky. Now you can lighten/darken the blues, add saturation, change the hue, change the color temp and so on. As long as you don't go insane, the changes will blend in seamlessly. Note that I now have two masks for the sky area: the whole sky and just the blues. Making changes on one may involve going back to the other to adjust for effect. It is an iterative process.

Do the same for the rock area. I would like to see the highlights on the rocks brought out a little more. Increasing contrast seems to lead to a harsh result so I would try selecting a prominent highlight area as a mask and work on that.

Depending upon what you want to achieve you can get very natural results or go over the top.

Forgive my long post but I am really stoked over this program and no, I do not have any affiliation with this program. I just want to get the word out that it is worth checking out. That said, a few warnings. There is little documentation available. You have to learn by trial and error but it is not too bad. It took me awhile to figure out that the right button press converts the selection tool to erase. The rest is pretty intuitive as you can see the effects as you move the sliders. The little colored boxes beneath some sliders allow you to change the color effects by dragging points up or down, ie increase yellow saturation but nothing else. There are some major things still missing such as chromatic aberration removal, variable brush size, etc but there are usually workarounds. The developer has said he is working on these things and updates come frequently so expect things to get better. He seems to be a one man band but has done excellent work.

Some other things I have noticed. The control over color is very well done. Unlike some of the other programs, the color transitions are smoother, not harsh and contrasty. The colors have good saturation but don't look garish. Control of highlight recovery is well done. I shoot into the sun a lot for sunrises and sunsets. On some programs the transition from the sun to bright sky areas gets all funky-banding and weird colors introduced such as sun area, a red/yellow area around the sun (normal), the a greenish area (not normal), the back to the red sky. I have not noticed this with SNS.

I have attached a recent example that I did in SNS. Multiple exposure catch, I think I used two exposures in SNS. I almost deleted this image as out of the camera it looked pretty worthless. Now I rather like it. Made extensive use of masks and it did not take too long to process.

Erik, if you are still here would you be up to sending me the file? I would process it as I normally would and would keep track of the steps in tutorial form and post the results. It would be interesting to see what could be pulled out of it. I would aim at a fairly natural rendition a little on the dramatic side.

Larry
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ErikKaffehr
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« Reply #18 on: January 03, 2012, 12:01:09 AM »
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Hi,

Here is the original DNG image, with my initial adjustments.

http://echophoto.dnsalias.net/ekr/images/Psychadelic/20100801-_DSC7524.dng

Best regards
Erik
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leuallen
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« Reply #19 on: January 03, 2012, 01:36:42 AM »
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Erik, here is a quick edit. I used 6 masks, none of which took over a minute or two to create. I tried too keep the look similar to what you sent. Notice the extra detail in the rocks. I selected a bright area of one of the rocks to create a mask. The mask contained only the rock highlight areas so one pick did it. I then lightened and adjusted midtone contrast of the rocks mask slightly for a little more snap.

Also note the whites in the sky selected with one click. I opted for more contrast in this area but I could have made it as soft as yours if desired. None of the whites are blown. Seemed to achieve good detail in this area. The sky mask was made with one click selecting a blue. Brightness was reduced and saturation increased. Increased color balance warmth-more for the foreground and less for the sky (to keep good blues). One click selection of golden grass tones-played with saturation and brightness.

Took into LR. I usually make my final tweaks there as I know how it is going to print for there. Increased contrast slightly, added a little vibrance, and put a graduated filter on the foreground grass running diagonally (-.5). Reduced saturation of blues slightly as I had too much in SNS. Cropped to 16:9 as yours. So you like the 16:9 ratio? I use it quite frequently as I use a GH2 and the aspect ratios can be changed very quickly without any penalty for cropping. This allows me to see the final composition in the camera without trying to visualize what the crop would look like.

I could have gone many different routes with this image, all quickly and without too much effort.

But the image I was referring to was your second image on Dec. 8. I think I could do more with that.

If there is enough interest, I will put together a PDF with screen shots and how the masking process works. If not enough interest, skip it, for it is a lot of work to put together.

I could have probably obtained a similar result using just LR and PS but this was much easier.

Thanks

Larry

On looking at the conversion after posted, it looks a little flat and could use more foreground staturation. Oh well, I don't usually process for the web, I usually print anything that is worth anything. In other words for the web I would push it more over the edge for more drama and to compete with other images. For the web, I think you can get away with this as the image is usually on viewed briefly. In print it lives a longer life and the jarring impact wears thin.

« Last Edit: January 03, 2012, 01:46:34 AM by leuallen » Logged
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