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The Definitive Guide to Realistic High Dynamic Range Images

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Leviathor is a group administrator Leviathor says:



We have all seen them. The alien worlds. The velvet paintings. The collision of photography and flamboyant computer graphics effects.

This tutorial is none of those things.

This tutorial will attempt to demonstrate how to make a realistic HDR, one that is virtually indistinguishable from a single exposure. The biggest goal is producing a tutorial that can stand as a standard by which anyone can learn to create a balanced HDR. Ultimately, the processing choices are yours. These are the building blocks.

Before we start, some background about high dynamic range (HDR) that are often misunderstood or misconstrued. HDR is two or more exposures, and in many cases, more is not necessarily merrier. For simplicity's sake (Occam's Razor), use only the minimum number of exposures to cover the dynamic range of the scene. Today's auto-bracketing features allow for a neutral image, plus an exposure on either side of the neutral image (±1/3 stop to ±2 stops). A proper exposure on a decent digital camera covers about six stops of information; bracketing at ±2 renders approximately ten stops of information. That is enough to cover all but the most extreme circumstances, like shooting into the sun, or interiors with wild lighting.

HDR is not a new fad in media--HDR has been used in cinematography since the days of Westerns. Any time the cowboy rides off into the [perfectly exposed] sunset where all the foreground is also perfectly exposed, that was HDR. Including artists of paint and pen, HDR techniques have been around for centuries.

Terminology with respect to HDR, while minimal, can be rather touchy. The two biggest issues are high dynamic range imaging and contrast. High dynamic range imaging is a technique to bring out the details in both light and dark extremes of an image. Contrast is more confusing. Local contrast is the contrast between adjacent components within the photo. A high local contrast will increase the perceived contrast of the entire image. A common complaint is that HDR images have less contrast than single exposures. Of course they do! The shadows and highlights are being expanded, then compressed into the same eight bit dynamic range as any other RGB image. However, with skillful processing, increasing local contrasts in the image will go a long way towards making the HDR merge amiable.

Enough rambling. On with the tutorial!

Materials:
Canon 20D;
Three auto-bracketed exposures: -2 EV, ±0 EV, +2 EV;
Adobe Photoshop CS2 (Photoshop 9.0.1).

Outline and Procedure:
I pondered long on how best to demonstrate this technique. First, I thought that just a run-of-the-mill, step-by-step tutorial would be easiest. Then I realized that my plug-and-chug tutorial would not offer any more insight than any other plug-and-chug tutorial. So I decided that I would take the three-exposure bracketing of the Canyon de Chelly (pictured at top), and make the plus and minus two exposure value frames, respectively, look "exactly" like the perfectly-exposed middle exposure. So, basically, I am taking the -2 EV and +2 EV frames, and merging them to look like the 0 EV frame.

"But, Mr. Leviathor!", you say, "You just said that HDR images can't look like single exposures and you said that you were going to make them look 'exactly' like one another!" Well, through the magic of Photoshop, I will get it pretty darn close. Noticeable in the HDR will be extra details in the shadows, and some richening of the highlights. Spending a lot of time to make an HDR look realistic is not always required--I just had an original to "copy". Now would be a good time to mention that I used both a circular polarizer and a two-stop graduated neutral density filter. Did I need to process this as an HDR? No, and I typically would not--in fact, I would advise against it. However, this is purely for demonstration. For posterity, if I did not have a GND filter, I would have had to use HDR.

First, navigate to File > Automate > Merge to HDR.



This will open a dialogue box which looks similar to:



1 & 2. "Use" files allows you to browse for the RAW files you want to use. "Folder" looks for a folder (surprise!) with RAW files to merge. "Open Files" uses the RAW files already opened in CS2.

3. I only use "Automatically Align" when merging handheld images. Aligning the images takes significantly longer than merging without alignment.

4. OK! Which will bring up this window:



I used a smaller zoom and cropped out some of the dead space to make the image a more manageable size. Visible here are:

1. The source images. Prep work in Adobe Bridge: I ensure that the temperature and tint values for all the to-be-merged images are the same. I uncheck all the auto-correction boxes. I never use Bridge's sharpening algorithm. Now, you will notice that PSCS2 made the darker image 0 EV and the lighter image +4 EV. You will notice, however, that one is overexposed, and one is underexposed. For whatever reason, Photoshop will always put the darker image of a pair at 0 EV. It does not do this for three exposures.

2. Preview of the 32-bit merge of the 16-bit originals.

3. Gamma-adjustable histogram. CS2 does a very good job of picking a proper gamma. If you desire to change it, you may. In fact, I encourage that you play around with it just to see what happens. If you want to reset it, just press the ALT key (PC) and press the Cancel/Reset button.

4. Whee! Next, convert the image to a modifiable 16-bit image:



Image > Mode > 16 Bits/Channel.

This is where the magic happens. Getting this part right will go a long way towards making your image shine. If you made mild mistakes earlier in the process, they can be partially recouped in this step. But, like photography, starting with a better image will make processing easier and the end results more stunning.



1. Method. The algorithm by which the image will be processed.
a. Exposure and Gamma: This will allow you to adjust the brightness and perceived contrast.
b. Highlight Compression: This is a one-click algorithm which compressed the highlights into a 16-bit range (or 8-bit).
c. Equalize Histogram: Equalize histogram compresses the highlights and shadows while preserving contrast--the quickest and easiest way to create realistic high dynamic range images. I am using it in this example for ease.
d. Local Adaptation: My favorite. Manually adjust the tonal range of the HDR image via a curves-like algorithm over the image's histogram. Also has threshold and radius adjustments.

2. Toning Curve & Histogram is only usable in Local Adaptation. I keep it open, because I typically use Local Adaptation, and I like to see what sort of information I am dealing with.

3. Zing!

Somewhere between processing and making screenshots I lost the original processing of my single exposure, so I had to reprocess it. I'm not quite as happy with these results, but they get the point across.

Single-exposure:



HDR composite:



Conclusions:
Mastery of Photoshop is not required. First and foremost, master your camera. Understand that exposing correctly is important. Expose such that your 0 EV exposure is exposed right, then include the highlights and shadows (±2 EV, typically).

The second thing to keep in mind is self control. Often time the difference between a great HDR and a flop is too much: Too much saturation. Too much contrast. Too many highlights or shadows. Don't work hard to save detail in the extremes, only to erase it again with heavy-handed curves or shadow/highlight adjustments.

Understanding that HDR does not save failed images. A failure is a failure. Period. It is harsh, but it is also reality. Additionally, HDR, when used improperly, can ruin successful images. It happens all the time.

Finally, it is possible to create rather spectacular HDR images that look like a single exposure.

PS. If wanting to duplicate or reproduce any part of this, please contact me. I consider this a body work, much like the photographs before you.
Originally posted at 10:47PM, 17 August 2006 PDT (permalink)
Leviathor edited this topic 84 months ago.

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Jaffa2004 (moving to new account) PM for info says:

Genius.. I can't wait to put this to work
93 months ago (permalink)

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Jeff Clow says:

This is one terrific tutorial, and although I don't have Photoshop CS2 (I personally use Photoshop Elements), I found your instructions and insights truly fascinating.

Thanks much for taking the time to post this......
93 months ago (permalink)

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Computer Science Geek says:

Thank you so much! :-)
93 months ago (permalink)

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makelessnoise says:

...how to make a realistic HDR, one that is virtually indistinguishable from a single exposure.

That really is the key. The over-worked HDR images that you see all over had put me off on it. I anticipate, though, that in the future cameras will do this automatically. A quick 2 or 3 exposures and then apply an algorithm and you're there. Until we invent sensors with a higher dynamic range, we'll have little choice but to take successive shots.

So thank you for this. Clear and straightforward and you have demonstrative proof that HDR can look terriffic. (Now if I can only cough up the $ to go from PS6 to CS2!)
93 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

If you have an Elements CD key, you can get CS2 for $350 under retail from Adobe in a Canon/Adobe special. It's been running all spring and summer, but I don't know when it's going to end.

store.adobe.com/store/products/master.jhtml?id=catCanon
93 months ago (permalink)

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DaniCast says:

Really brilliant explanation, thanks for share it :)
93 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

I wish topics had a view tracker, like pictures, then I'd know if people were actually looking at this. :P
92 months ago (permalink)

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wmliu says:

i am. :-)
92 months ago (permalink)

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Fort Photo says:

Me too! Very good stuff.
91 months ago (permalink)

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Dr DAD (Daniel A D'Auria MD) says:

Thanks for the tutorial. Helped answer a few questions I had. My only remaining question is how best to save the image. CS2 will automatically save the 16 bit image as a PSD file. Can this be converted to Jpeg?? It does not appear to be a "save file" option.
91 months ago (permalink)

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Computer Science Geek says:

Dr DAD you need to convert the image to 8-bit mode to save it as a JPEG.
91 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

Thanks for the help, Phillip. (=

Convert it to 8-bit, then Save As. The Save As quality doesn't need to be higher than 10 (it goes to 12) for web or "most" printing.
91 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

Would anyone like to see some more specifics about any part of this? I was thinking about doing a more detailed description of Local Adaptation, if there's any interest.
91 months ago (permalink)

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donnacv says:

I thank you profusely for the basic tutorial and I for one would love to see more detail on Local Adaptation.
91 months ago (permalink)

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Computer Science Geek says:

I for one would love a more detailed examination of Local Adaptation.
91 months ago (permalink)

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tony's pics says:

I'm also interested in details on local adaptation, thanks a lot for the well written tutorial.
91 months ago (permalink)

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s3igell says:

Any hope to translate this HDR Tutorial for those of us with PS Elements4 ??
90 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

Does Elements support HDR? I am not familiar with Elements.
90 months ago (permalink)

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Enlightened Fellow says:

Good tutorial on realistic HDR. I've been considering doing one for my photomatix process. It would be a little more complicated to write up, I fear.

Oh, elements doesn't support HDR, so s3igell is out of luck for now.
90 months ago (permalink)

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Kurt Kramer says:

I've tried this and though my two images were 3 or 4 EV apart, I got a message that the two exposures weren't different enough for CS2 to apply HDR. A friend had the same experience. Have you encountered this? Am I missing something, or do I really need to experiment to see how many stops difference I need between images?
89 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

I have never received this message, but I know Photoshop requires unique EXIF information for each image. If you have one RAW and generate two JPEGs from that file, each JPEG will contain common EXIF from the original RAW. There are programs to edit/change/add EXIF information, but I am not familiar with them, and do not know if they would "trick" PS into allowing their usage. I think it might, but that's just a guess.
89 months ago (permalink)

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Kurt Kramer says:

Thanks for your reply. If I may pose a follow-up response/question: The two images are scans from scenes captured on film, two different negatives shot within seconds of each other using the auto-bracket function. What would that imply as far as the EXIF information? Is there any?
89 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

If there is any embedded EXIF, it would be from the scanner, if your scanner has that ability. Maybe try saving it using "Save for Web" instead of "Save As". Web strips EXIF information.

It's pretty confusing that scans would tell you that there's not enough range. Very odd.
89 months ago (permalink)

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Computer Science Geek says:

Well, in this situation, my guess is that the images are identical based on the EXIF data added by the scanner. Best to strip it out in this case.
89 months ago (permalink)

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javame says:

I really really appreciate this!
89 months ago (permalink)

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Mace2000 says:

Thanks for this tutorial. I create my HDR images with Photomatix because I don´t have a copy of photoshop. Though I learned some things about HDR and will try to transfer them to Photomatix.

Thanks and regards,
Matthias
89 months ago (permalink)

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Kurt Kramer says:

Just wanted to report that I had a situation of strong morning light shining through blinds across sections of the Sunday newspaper sitting on a dark carpet. Perfect test situation for HDR. Got out a tripod and took two images, one at +2 and one at -2. Shot one, also, as read by the meter. Take a look in my PhotoStream. This looks to be a great tool. Thanks for your input.
Kurt
88 months ago (permalink)

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Kurt Kramer says:

An English magazine called Practical Photography just did a feature on HDR. They used a product called Photomatix Pro v.2.3.2. They said "There is an HDR function built into Photoshop CS2, but it doesn't offer the range of options and controls available in the Photomatix software, so the results are more difficult to get right and require more extensive adjustments of the combined image." Has anyone used this product? Is it worth buying?
88 months ago (permalink)

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jodi_tripp says:

wow, this is great. I have used photomatix and I like it. I recently have upgraded my elements to CS2 and now the Beta cs3 and I was unsure how to process them after merging them. I will have to try this out. Photomatix has a free trial worth using. I think it is fairly easy to use... There are some good tutorials around to give you pointers as well. It will be fun to compare the difference...
88 months ago (permalink)

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elnfortinbras says:

s3igell...
I have Elements 4 - it doesn't provide an HDR function...
88 months ago (permalink)

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Tmuna Fish says:

Is it better to use three raw images. Does that help?
87 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

If three helps you achieve a more complete range, then three is better. A lot of redundancy is not necessary; using images outside of the dynamic range will not help, either, as the information will either (1) force the algorithm to include or attempt to use too much information or (2) just be thrown out in a natural-looking HDR.
87 months ago (permalink)

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Kurt Kramer says:

Leviathor: do you have a comment on the Photomatix program versus HDR in Photoshop?
87 months ago (permalink)

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Neil D. says:

Thanks for taking the time to put this out there for the masses to try out. I haven't tried it yet, but I have an interest in producing realistic-looking images and this will be a very useful technique to master, especially when considering that our view of the world using our eye/brain system perceives much more dynamic range than the current digital cameras can match (this may not always be so, but for now we need HDR methods).
87 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

Kurt, I don't have any first-hand experience with Photomatix, but have seen both good and bad things come from their software--more unnatural than natural, sadly. I don't doubt there's a learning curve associated with producing quality images with Photomatix, just like there's a rather steep learning curve for Photoshop, but people seem to jump on Photomatix and expect good results with little work. Part of this, I think, is due to Photomatix's huge popularity with reaching the Explore Top20 (Front Page), where Jeff, Lawrence, Asmundur, John, and others have made its existence very well known to the world. It has nothing to do with how "good" or "bad" their work is; those guys make HDR look easy, so everyone goes and gets a copy of Photomatix expecting similar results. Reality sets in and its results are all over Flickr.

When I read something like, "but [Photoshop] doesn't offer the range of options and controls available in the Photomatix software." I read, "Photomatix has lots of buttons, sliders, presets, and gizmos, where Photoshop requires getting one's hands dirty." A familiarity with either program will give good results. It's more difficult to find realistic renditions on Flickr from Photomatix, but they're out there, so I know its possible.

Once one gets a working knowledge of Local Adaptation, and sees how to apply a curve to it and adjust its Threshold and Radius, the results are pretty much set once the 16-bit conversion is done. Sure, one has to go through and maybe check levels and apply curves or something, but other than basic stuff that would be done for a single exposure, it's no more fuss than usual.
87 months ago (permalink)

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Dirk Delbaere says:

Thank you for sharing this. I tryed it a few times and this one is done just like you told with 4 exposures and Local Adaptation.
Trees
86 months ago (permalink)

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Cliff Stone says:

Thanks for sharing this! I found this tutorial from a link to a nice HDR that had a reference to it.

There are so many terrible HDRs on flicker that I really appreciate you having taken the time to show how to do it right!!

I've not yet sprung for PS2, but I've played with Photomatix. One of these days I'll get it right too. Thanks again!
85 months ago (permalink)

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lentedorafa says:

Many thanks for taking the time to do this.
84 months ago (permalink)

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Kurt Kramer says:

I've read your tutorial and done some experimenting. Thanks for such a thorough explanation. The other night I also looked at an HDR tutorial at Luminous Landscape and was surprised to see a fundamental difference. You prescribe using images still in their RAW format. Actually I am a little puzzled by your advice that you "ensure that the temperature and tint values for all the to-be-merged images are the same." So my first question: Do you do that by selecting a the same color balance in your camera for all shots? Or might you open each image in Camera Raw and select the same color balance, then clicking Done so that Camera Raw saves the settings? But I digress...the fundamental difference in the Luminous Landscape tutorial is that they advise using .TIF or .PSD files, saying, "If you have done the shots in RAW mode you will first need to process the files, preferably into TIF or PSD format. Ideally you want to keep them in 16 bit mode.....Be careful as well when RAW processing that all of the files are processed with the same parameters, something, by the way, that Camera Raw 3.0 does very nicely."
My main question is: Is this just a matter of choice? I am amazed that two trusted sources would differ so greatly. Any comments?
82 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

I haven't ever processed an HDR from a processed TIFF or otherwise. I will have to look it up and see if they give an explanation. I do it directly from RAW (selecting the same color temperature and tint values) as it preserves the greatest amount of information. A 16-bit (or higher) TIFF or PSD might render something similar, but I've not tried it.

With ACR you can adjust (if you like) all the basic parameters that can be applied in a processed file, and do it without impacting the quality of the original images. I suppose processing to a 16-bit TIFF *might* speed up the HDR workflow a bit, but then there's time spent getting to the point of beginning the HDR blend. Then after the HDR algorithm and tone mapping has been completed, the image would have to be processed yet again to restore contrast and make some localized tweaks. All the while, the processing is now comparatively destructive as opposed to doing the original tweaks in Adobe Camera Raw.

To touch on the color temperature one more time: Say the algorithm was averaging three values of gray. If the grays weren't similarly tinted, the average would be taking into consideration some color value, and applying that to the final result. The change might not be that drastic, and probably wouldn't be uncorrectable, but shadows might start creeping, turning too warm or cool to be believable. Clouds might go from white to red, or gray to blue. I guess this is, in essence, getting it right "in the camera".
82 months ago (permalink)

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Kurt Kramer says:

Thank you again for your advice. Just so I understand this idea of : You wrote, "With ACR you can adjust (if you like) all the basic parameters that can be applied in a processed file, and do it without impacting the quality of the original images." Let's say I open RAW image number 1 and I set the exposure at 5200 and the tint at 4. But I have to save that some how so that I can do the same thing to RAW images numbers 2,3, and 4. I think the way to save those settings to "ensure that the temperature and tint values for all the to-be-merged images are the same." is to select Done (not Save, not Cancel). My understanding of doing so is that exposure/tint settings are saved,without modifying the original data collected when exposing the sensor to create the RAW files. In this manner the shadows and the clouds all have the same exposure/tint from image to image and CS3's HDR routine doesn't have to deal with any variations of those types. Sound right?
82 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

That's correct. Done will apply the settings without opening the file. Also, if you right click, there is an option labeled "Previous Conversion". What this does is apply the last changes to whatever files are selected when you right click to apply the previous conversion.

Keep in mind that this applies all the changes you made to the last image, so if you adjusted shadows, contrast, and exposure, along with color and tint, all of them would be uniform after the conversion. If you just change the color and tint, then do the previous conversion, then the tint and color will be the same in all selected files. This is a very easy way to apply white balance to a whole lot of images, if you have a gray card.
82 months ago (permalink)

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Kurt Kramer says:

Wow. Bonus info. Thanks!
82 months ago (permalink)

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captured by corey says:

Thanks heaps for your step by step tutorial! Here's my first attempt:

Sunset HDR
81 months ago (permalink)

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mpurciel says:

Thanks for sharing! This will definitely help me with shooting with slide film.
79 months ago (permalink)

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rui "the Mix" correia says:

thanks for sharing ,very nice tuturial
tks mate
76 months ago (permalink)

Shantelleb [deleted] says:

wow thanks for sharing will give it a try
69 months ago (permalink)

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dannysoar says:

You write that . .
HDR is not a new fad in media--HDR has been used in cinematography since the days of Westerns

So I gather it can be done without an advanced Photo$hop. I have seen some wonderful B&W HDR pictures and would like to figure out how to do this with an early Photoshop elements. If you can't offer a step by step tutorial can you explain the basic idea- what it is that the full Photoshop is doing.

Thanx
69 months ago (permalink)

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gregpphoto says:

All HDR really is is the capturing of the full range of shadows, midtones, and highlights. Just take one exposure for each (dark, mid, and bright), than manually combine them with masks if you don't have the automate>merge-to-HDR tool. In fact, even though I use CS2, I have never been happy with the automate process, I always combine my images as though I were playing with a split ND filter.
Originally posted 52 months ago. (permalink)
gregpphoto edited this topic 52 months ago.

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Leviathor is a group administrator Leviathor says:

Yep, and the bare minimum is two exposures, one overexposed for the shadows, and one underexposed for the highlights. I think it was Outdoor Photographer this month that had a pretty decent article on HDR, both with somewhat selective tone-mapping, and by manually masking images together--a method I enjoy quite a bit now.

If the 'lesser' Photoshops have the ability, any sort of making should allow manual blending. The algorithm for automated HDR and tone-mapping is probably a bit above Elements' pay grade, though.
52 months ago (permalink)

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garmahis says:

Here's more about Realistic HDR photography in Photoshop using layers and masking. Very simple.
52 months ago (permalink)

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duncande150 says:

Great post. I'm new to HDR but the ones I've done so far, I try to keep pretty realistic and just enhance the exposure. -Del
50 months ago (permalink)

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root88 says:

If the image is going to be indistinguishable from a single exposure, why even bother with HDR?
49 months ago (permalink)

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Leviathor is a group administrator Leviathor says:

The goal, for realistic HDR, is to take those several frames and make them look as if they could have been captured with one exposure, when the actual scene in front of the lens makes it exceedingly difficult.

There are times when "HDR" and tonemapping are used when it is not needed, typically rendering surreal images, or images that are quite easy to pick out as processed. However, when one compresses into one image several images that exceed the range of sensitivity of one's sensor, then the phrase "high dynamic range" is applicable.

Physical, glass filters can--and are--used in front of a lens to help control the illumination of a scene. Take a look at Lee Filters or Singh-Ray to see a pretty exhaustive list of examples. However, filters have their issues, too. Additional glass always degrades the image. Horizons and gradients won't always be perfectly flat or 'nicely continuous' for hard- or soft-edged filters. The stop ratings on the filters are static, which can be used for artistic purposes (say, a sky filtered darker than the foreground), but that can look equally unrealistic to some of these heavily tonemapped abominations. When such filters can be used well, though, they do produce some rather impressive results: Galen Rowell filtered rather heavily (and did a lot of the sky-darker-than-foreground shooting, which I am cool towards).

Another confusing explanation: If the scene is wildly out of the range of sensitivity for the camera, HDR would be analogous to having the power to reduce the exposure value of a bright sky, and increase the exposure value of deep shadows, with some sort of user-friendly, landscape-setting tool. This is, of course, slightly beyond human ability, and ludicrous.

There will be a time when tonemapping is all that remains, as the technology for a higher dynamic range sensor will eventually be 'the' thing to get.
49 months ago (permalink)

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