Why (auto) HDR inherently sucks

Nikolai

Well, the answer is simple: it's "auto", hence it's ultimately stupid....:dunno

Let's have it: what is an HDR from a purely mathematical standpoint? A meager attempt to take a collection of 32-bit floating point numbers representing each pixel and put them into a similarly sized collection of 16-bit (or even 8-bit) integers.

Ever tried to pour 32 ounces of liquid into 8 ounces glass? Well, if you did, you'd know: 75% of your liquid is gonna spill. Now, the important questions is - which part?
If we were talking a real uniform liquid, or, in photographics terms, 50% gray image, we wouldn't care. But the whole point of taking an HDR image is to have most of the pixels different. Hence, we're up to a certain Sophie's choice. We have to sacrifice 3 out of each 4 pixels. And what tool do we have for it? Well, the best case scenario - one "local adaptation" curve. Which, mind you, doesn't care about channels, or where the particular pixel is located - on the face of a beautiful girl or on the undercarriage of the dirty car. All it cares is about the luminosity (combined RGB) value. No wonder every auto-HDR-ed image has this typical "HDR look", similar to one you get if you get too far with "shadows/highlights" slider (this analogy is actually very accurate). Random pixels all over the image suddenly change their luminosity value, resulting into those lame and totally unnatural grayish shadows, what I call a "corpse look".:dunno Of course, it can be great for special effects (especially in advent of Halloween;-), but hey, so is the "rubber stamp", and the whole set of "artistic filters".

Way out? Forget the HDR tool. Use old good layers and masks. It's not really that hard. You, as the photographer, know precisely what should be dark and what should be bright. The tool doesn't know, and what's worse, it doesn't care. You know, and you care - hence more power to you! :thumb

HTH

jogle

there's nothing stopping them using a 32bit raw format and setting the black and white points so that there is more info in the seemingly blown out whites and details in the seemingly crushed blacks. They could even use the openEXR format which is in heavy use in film post production for doing just that. Your images are stored in 0 - 1 values. 0 being black and 1 being white. By using a true 32bit float, you can have values over 1 and values under 0.

Nikolai

jogle wrote:

there's nothing stopping them using a 32bit raw format and setting the black and white points so that there is more info in the seemingly blown out whites and details in the seemingly crushed blacks. They could even use the openEXR format which is in heavy use in film post production for doing just that. Your images are stored in 0 - 1 values. 0 being black and 1 being white. By using a true 32bit float, you can have values over 1 and values under 0.

True.. But... As of now there is no mainstream hardware (cameras) or software that would provide a possibility of true 32-bit workflow. RAW data are 14-bit at best and even in PS most of the tools woul not work in 32-bit mode, thus rendering it fairly uselss. I'm not even talking about print side of the story...

Rhuarc

I actually have a few HDR images that I need to put together soon, any good advice or tutorials on the best way to do this using masks? I mean what type of feathering and brushes do you use?

Thanks!

Nikolai

Rhuarc wrote:

I actually have a few HDR images that I need to put together soon, any good advice or tutorials on the best way to do this using masks? I mean what type of feathering and brushes do you use?

Thanks!

Simply load them in layers, add masks, start with general gradients, then use large soft brushes . It's really faster/easier to do than to explain.

Rhuarc

Nikolai wrote:

Simply load them in layers, add masks, start with general gradients, then use large soft brushes . It's really faster/easier to do than to explain.

LoL, ok, will do! I hope you are right!

kdog

Nikolai wrote:

No wonder every auto-HDR-ed image has this typical "HDR look", similar to one you get if you get too far with "shadows/highlights" slider (this analogy is actually very accurate). Random pixels all over the image suddenly change their luminosity value, resulting into those lame and totally unnatural grayish shadows, what I call a "corpse look".

Hi Nikolai,

Does this one have the "corpse-look" you described?


Cause if it does, then I guess I like the corpse look. Tools like Photomatix are becoming extremely popular, even with some very excellent photographers. So you're saying they're all producing bad images? I mean you did say "every".

And honestly, I think you've greatly oversimplified what these tools do. There are 15 sliders and other adjusters in the Photomatix Tone Mapping/Details Enhancer tool alone, the combination of which provides an infinite amount of adjustability. And that doesn't even include similar sets of controls in the tone compressor, or exposure-blending tools. Fortunately, like any other tool, you develop your own style and ways of using it so that you don't have to tweak every control every time. Eventually, your techniques evolve and hopefully improve. I'm in the embryonic stages with what you call "auto-hdr", and so far I'm digging it. Can I do the same thing with layer masks and brushes? Possibly, but certainly not as quickly and with the repeatability that a tool like Photomatix gives you.

I mean, how would you make your clouds look like this using layer masks and brushes? You'd be at it for a very long time, but it only took seconds to do in Photomatix.

Of course, one might argue why would you want to make your clouds look like that, and that's a different argument. However, it's what I wanted in this shot, and I think it's a fair representation of the actual scene. I think there's a LOT that these tools give you that really cannot be accomplished any other way. You mentioned the holloween-look. So what's wrong with that if it's what you want?

These auto-HDR tools are like anything else -- just another tool in your collection which you can draw upon, depending on what you want to accomplish.

Just my 2 centavos.
Cheers,
-joel

Rhuarc

Here is a question, do the Photomatix plugins for CS3/CS4 give the smae tools as the stand alone program? I would like to do everything from one program if able.

kdog

Rhuarc wrote:

Here is a question, do the Photomatix plugins for CS3/CS4 give the smae tools as the stand alone program? I would like to do everything from one program if able.

From their website:


Differences standalone Photomatix Pro versus Plug-In

Photomatix Pro is a standalone application. It includes HDR Tone Mapping and Exposure Blending among other features. Images produced with Photomatix Pro can be further processed in any image editing application. The Tone Mapping Plug-In is a plug-in. It offers only one Tone Mapping method and works within Photoshop CS2, CS3 or CS4.

Advantages of Tone Mapping with the plug-in
- You don't have to leave Photoshop

Advantages of Tone Mapping with Photomatix Pro
- Integration with easy-to-use Batch Processing
- Ability to tone map larger HDR image files (the plug-in is limited to sizes between 30 and 40 MegaPixels).
- No need to change the bit-depth of the 32-bit HDR image after tone mapping.
- No need to adjust the exposure when Tone Mapping is applied directly after creating HDR image (with the plug-in, tone mapped image may show black artifacts when an incorrect 32-bit preview option is assigned by Photoshop).

jasonstone

Nikolai wrote:

It's really faster/easier to do than to explain.

I'd have to politely disagree on that point...

Everything is black magic until someone takes the time to step you through it for the first time - then you say to yourself - "oh yes! of course! it's obvious now..." However, until then it's about as clear as mud

Maybe a tutorial somewhere would give people, myself included, a better idea of what you mean. I have an inkling (a really small one) of what you're hinting at, but I don't see how I could do a HDR effect processing just using layers in PS.

Or maybe a comparison of Photomatix HDR vs PS Layer processing - that'd be really interesting to see!

Cheers, Jase

Dee

No wonder every auto-HDR-ed image has this typical "HDR look", similar to one you get if you get too far with "shadows/highlights" slider (this analogy is actually very accurate).

I love HDR, "IF" done properly, the idea is to make it look "natural." I often think of "going too far" with shadow/highlight as not going far enough. Some people tend to go with the default which leaves a decided halo on the contrasty edges. I find pulling the sliders all the way to the right works much better than leaving them to the left.

I haven't used an HDR program, so I'm not sure exactly how it works. I usually use shadow/highlight, masking, curves, sometimes levels, and a lot of hue/saturation to get my point across, and then more masking. This is working in .jpg, not raw.

Kdog, your photos look fine, except for the clouds, a little too much "blue" in the gray, and too much of that particular shade of blue in the sky. I'm not sure if you are emphasizing the scenery with the red rocks, or are emphasizing the clouds, just my opinion, but I think less blue in the clouds and the sky would still give the emphasis you are wanting. But, that's just my opinion

I do love the yellow trees! That looks totally natural to me and believable.

Nikolai

Joel:
you're totally missed my point, my dear F-stop :-)
I specifically mentioned I was not taling using HDR tool as a special effect one.
What I was talking about its inherent inability to make correct adjustments based on the image content (i.e. pixel value AND position) rather than on the pixel luminosity values only.

And you're obviously mistaken saying it takes a long time doing through layers, masks and brushes. It doesn't. In fact, it's MUCH FASTER than going through HDR mode, and at the same time you are in complete control.


Jase:
did you actually try to follow those simple steps I suggested to Rhuarc? Because if not, no collection of internet tutorials will help. At some point you have to stop reading and start doing.

Nikolai

Dee wrote:

I haven't used an HDR program, so I'm not sure exactly how it works. I usually use shadow/highlight, masking, curves, sometimes levels, and a lot of hue/saturation to get my point across, and then more masking. This is working in .jpg, not raw.

Hi Dee, :-)
I wasn't talking about high dynamic range imagery in general.
I was referring specifically to an HDR tool . I should've being even more specific and say that I'm referring to Photoshop HDR tool.

jasonstone

Nikolai wrote:

Jase:
did you actually try to follow those simple steps I suggested to Rhuarc? Because if not, no collection of internet tutorials will help. At some point you have to stop reading and start doing.

I'm doing alright - but I don't know exactly how to do what you're suggesting... like i said black magic until you've seen it once or done it

Do I have darkest exposure on the bottom? regular exposure in middle? over expose on top?

Do I use blending layers??? to try and get some detail out of each layer?

If I want the dark layer (assuming on the bottom) to show through do I need to make a layer selection on both top two layers?

I'm not a photoshop layer expert and maybe that's why I don't know exactly how to approach what you're suggestion.

I'm more than willing to give it a try once I know though!

Try anything once!

Cheers, Jase

pathfinder

Jason, blending two images - one lights and one darks ( they can be two versions from a single RAW file ) is straightforward, and the tutorial is here - http://dgrin.smugmug.com/gallery/1856992

Basically you use a mask to reveal one of the images by painting with the brush using black or white ink on the mask layer - black reveals and white conceals.

Nikolai

jasonstone wrote:

I'm doing alright - but I don't know exactly how to do what you're suggesting... like i said black magic until you've seen it once or done it

Do I have darkest exposure on the bottom? regular exposure in middle? over expose on top?

Do I use blending layers??? to try and get some detail out of each layer?

If I want the dark layer (assuming on the bottom) to show through do I need to make a layer selection on both top two layers?

I'm not a photoshop layer expert and maybe that's why I don't know exactly how to approach what you're suggestion.

I'm more than willing to give it a try once I know though!

Try anything once!

Cheers, Jase

Jase,
the funny fact is - it really doesn't matter.

• Start with just two exposures - one darker, one brighter.
• Load them as two layers, doesn't matter in which order.
• Add a layer mask to the upper one
• Select linear gradient tool
• Switch to default colors (black and white, doesn't matter which is which)
• Draw an approximately vertical line across the whole image, say from top to bottom
• If the effect is opposite to what you expect, draw it again, now in opposite direction (from bottom to top).
• That's all.

Once you get a grasp of it, you will decided which way is more comfortable/logical for you to arrange the files, etc.

Nikolai

pathfinder wrote:

Jason, blending two images - one lights and one darks ( they can be two versions from a single RAW file ) is straightforward, and the tutorial is here - http://dgrin.smugmug.com/gallery/1856992

Basically you use a mask to reveal one of the images by painting with the brush using black or white ink on the mask layer - black reveals and white conceals.

Thanks, Jim! Keep forgetting about those.

kdog

Nikolai wrote:

Joel:
you're totally missed my point, my dear F-stop :-)
I specifically mentioned I was not taling using HDR tool as a special effect one.
What I was talking about its inherent inability to make correct adjustments based on the image content (i.e. pixel value AND position) rather than on the pixel luminosity values only.

And you're obviously mistaken saying it takes a long time doing through layers, masks and brushes. It doesn't. In fact, it's MUCH FASTER than going through HDR mode, and at the same time you are in complete control.

"F-stop to Aperture, come in please." :giggle

Actually, I was talking about blending exposures, not special effects. The example I gave was the clouds. Storm clouds often have a fairly wide dynamic range that cannot be completely captured by the camera. So manually blending them from multiple exposures would be quite tedious, no? You might have parts of each individual cloud from each of three images. The HDR treatment of clouds is a big part of its appeal for me.

Nikolai

kdog wrote:

"F-stop to Aperture, come in please." :giggle

Actually, I was talking about blending exposures, not special effects. The example I gave was the clouds. Storm clouds often have a fairly wide dynamic range that cannot be completely captured by the camera. So manually blending them from multiple exposures would be quite tedious, no? You might have parts of each individual cloud from each of three images. The HDR treatment of clouds is a big part of its appeal for me.

"DUDE!" :-)
OK, hear me out. I'm not denying the need of blending multiple (usually bracketed) exposures together. All I'm saying that at the current state of technology, while most of the tools are incapable of processing HDR files (like those 32-bit ones) the automatic conversion of 32-bit image to 16- or 8-bit one that doesn't take the spatial properties into consideration inherently sucks. You can have similarly bright pixel both in sky area and in canyon area. Automatic process doesn't care WHERE it is, only HOW BRIGHT it is. Hence it would try to adjust ALL pixels with the same level of BRIGHTNESS. Which is wrong, imho, since simialrly bright pixels in different image areas MUST be treated differently.
That's why I suggest doing it manually with layers and masks.
Otherwise you get that infamous "corpse look".

Nikolai

OK, folks, allow me to demonstrate.

1: Here are three bracketed exposures from Castle Rock, Sedona, AZ



2: If you use Photoshop|Merge to HDR approach you'll about to wait for two lengthy conversion processes and then fiddle with one rather unintuitive curve. On my 3 year old machine (which is still OK, since it was pretty good when it was young) it takes about 5 minutes and ends up in somthing like this:



3: Now, if I simply load the files as layers, add masks and do the whole gradient/briush thingie, it takes less than two minutes and the result is as follows:



Which, from my perspective, is much closer to what I saw with my own eyes that lovely morning and what IMHO, is what all this HDR talk is about: compensate for camera/software imperfection and bring back the original impression.
No "corpse effect", fast and very effective.
Yes, you can probably get away with extra $99 and 15 sliders, but let me ask you: why?

jdryan3

You kids stop it right this instant!
F-Stop! Stop teasing your brother - you KNOW he is sensitive to this. You just enjoy picking at that scab.:poke

And Aperature, we know how much you hate technology and think CS4 is a delusion. See? Your PO'd at just that joke. RELAX! Auto-gray scale still sucks but a lot of people do it and are happy. Or use it as a jumping off point for greater things. You know F-Stop loves to needle you, and yet you let him get under your skin every time.:beatwax

Sheesh! The newbies would never know you guys are actually friends..:sweet

Nikolai

jdryan3 wrote:

Sheesh! The newbies would never know you guys are actually friends..:sweet

Always good when Uncle Shutter comes, even if nobody cried uncle yet

BTW that probably was the only frameset fom CR where you were NOT in the frame, DUDE!

kdog

Nikolai wrote:

BTW that probably was the only frameset fom CR where you were NOT in the frame, DUDE!

jdryan3

Not really more seriously, but Marc Muench did a session on exposure blending using quick selections and refining the edge. Pathfinder has a post here that covers the basics. I have to check my notes, but Marc tweaked the settings a little differently, especially on expanding the mask by 200 pixels. (I couldn't find a post by Marc on this, so maybe has his settings.)

And you can easily go crazy with different ways to get to the same place. Especially with Photoshop. The point being it doesn't matter as long as you get the results you want with a workflow you are comfortable with.

Nikolai

jdryan3 wrote:

Not really more seriously, but Marc Muench did a session on exposure blending using quick selections and refining the edge.

Marc was addressing slightly different issue with high contrast edges. I'm talking about fairly simple case.
And, btw, F-stop, your last shot of the Nothern Window is an exact example of the "corpse effect" coming from a luminance-only based automatic HDR approach

devbobo

Nikolai wrote:

Hi Dee, :-)
I wasn't talking about high dynamic range imagery in general.
I was referring specifically to an HDR tool . I should've being even more specific and say that I'm referring to Photoshop HDR tool.

Nik,

That's because the Photoshop HDR tool is totally shite....using any other method is going to be better.

jogle

Nikolai wrote:

snip....

3: Now, if I simply load the files as layers, add masks and do the whole gradient/briush thingie, it takes less than two minutes and the result is as follows:



Which, from my perspective, is much closer to what I saw with my own eyes that lovely morning and what IMHO, is what all this HDR talk is about: compensate for camera/software imperfection and bring back the original impression.
No "corpse effect", fast and very effective.
Yes, you can probably get away with extra $99 and 15 sliders, but let me ask you: why?

I'm sorry but this looks like the fake one to me. why is the reflection of the sky in the water brighter then the sky it's self?

The first thing that bugs me in any kind of HDR image is if there is something in the frame that is brighter then what it's being lit by.

pathfinder

Is PS4's auto HDR any better than CS3's?

I have Marc's numbers, and will make them available. I like them sometimes, but for sharp margins, sometimes I prefer others

Nikolai

pathfinder wrote:

Is PS4's auto HDR any better than CS3's?

Nope
And I don't think any automatic method is gonna be better....

devbobo

Nikolai wrote:

Nope
And I don't think any automatic method is gonna be better....

nik,

actually I beg to differ on that point. I took the image above (only had a small rez version) and chopped up the 3 images...and ran it through 'Exposure Blending' in Photomatix. The first 3 have the default settings and the final one i tweaked a bit.

Personally, I think the 4th version is far more realistic than your PS version...but of course I wasn't there

devbobo

I wasn't happy with the colour/lightness of the rocks in the previous version, so here's a different version...