[rm2]

Well, at least we have established that the automated HDR feature in Photoshop is sub-par. That was my whole point.

PS: Here is a very nice HDR of this image created using SNS by someone on DPR:

[sniper29a]

It is because professionals don't use HDR ;-) HDR tricks is for amateurs, who are impatient to do digital belnding properly and with maximum quality

[rm2]

It is because professionals don't use HDR ;-) HDR tricks is for amateurs, who are impatient to do digital belnding properly and with maximum quality

I take it you haven't seen this thread.

http://www.pentaxforums.com/forums/p...-tomorrow.html

HDR, when done right, is exquisite. And, professionals do use it. Sure, you can do further blending if you need to to achieve the result you are after. But many times, the initial HDR is quite sufficient and at the very least is an excellent starting point.



I wish I had had my tripod with me for this one so that I could have stopped down a bit more. Oh, well.

[newmikey]

Hey there rm2, these last 2 are beauties! Excellent examples!

And for those who would put HDR away as "amateur stuff", it should be nice to know HDR has been around for a long time and used by professionals going as far back as mid 19th century:

"The idea of using several exposures to fix a too-extreme range of luminance was pioneered as early as the 1850s by Gustave Le Gray to render seascapes showing both the sky and the sea. Such rendering was impossible at the time using standard techniques, the luminosity range being too extreme. Le Gray used one negative for the sky, and another one with a longer exposure for the sea, and combined the two in a single picture in positive.

High dynamic range imaging was originally developed in the 1930s and 1940s by Charles Wyckoff. Wyckoff's detailed pictures of nuclear explosions appeared on the cover of Life magazine in the mid 1940s. Wyckoff implemented local neighborhood tone remapping to combine differently exposed film layers into one single image of greater dynamic range."

For the purist, dodging and burning basically equals the analog version of HDR. It only stopped when "With the advent of color photography, tone mapping in the darkroom was no longer possible, due to the specific timing required during the developing process of color film. Photographers looked to film manufacturers to design new film stocks with improved response over the years, or shot in black and white to use tone-mapping techniques."

Then again, what we call HDR nowadays is based on tonemapping while what you and me use (DigiKam) is based more on a digital version of the old-era photographic HDR where the best-exposed portions of multiple negatives (image files) are combined to form one new image.

"Modern HDR imaging uses a completely different approach, based on making a high-dynamic range luminance or light map using only global image operations (across the entire image), and then tone mapping this result."

Below you will find 1 HDR image which was tonemapped with LuminanceHDR, followed by one exposure-merge done by DigiKam. You will agree that they look entirely different. The effect of exposure merging is more natural and, when done correctly, does not let on that it is a combination of images at all.

[raz-0]

I'll vote that both are pretty bad, but IMO the photoshop one is marginally less bad.

Photoshop's tools are not my favorite for HDR, but that was probably the worst follow up to claiming humiliation that I have seen in quite some time.

[rm2]

Newmikey,

Thanks for the info. I agree that the results from digiKam are generally more natural looking than those from other HDR (or HDR like) software. Many HDR photos have a foreboding, impending doom, look to them. One has to learn to tame that, it seems.

[newmikey]

Newmikey,

Thanks for the info. I agree that the results from digiKam are generally more natural looking than those from other HDR (or HDR like) software. Many HDR photos have a foreboding, impending doom, look to them. One has to learn to tame that, it seems.

An option that typically works well is to overlay the HDR image with the original and then, by varying the top layer's transparency, dampen the ominous/unnatural look. Best of both worlds, really.

IMHO, there is a different use/goal to both. Exposure blending just allows you to get the image as your eyes/brain perceived it but your camera was unable to reproduce out of the box. Tonemapping allows you to veer off and go wild - ultimately changing the image beyond what actually was there in reality.

[sniper29a]

HDR trick is modern trend of last of few years. wildly used by amateurs who still don't know what they do (and never will). Picture of beach is nice example. It is a picture from dream world, not reality. Perhaps it is some sort of art.

As newmikey says, insufficient dynamic range of SLRs, DSLRs is haunting pros for centuries. Result was was very simple. And used trick was taking as many pictures as necessary to cover whole dynamic range. Results of tone maping of HDR SWs (such as photomatic) is unrealistic dream picture.

Easier, most accurate way for me is take pictures with right exposure (exposed to right). Mask, them, adjust them as they suppose to be and then blend them. As landscape photographer. Dynamic range is very often problem for me and no HDR SW didn't give me satisfying result. Other than screwed up skies and unrealistic look.

Photomatix standalone/plugin (if anyone interested, i should sell it) is on my HDD for a year and used only in the beginning. Speed of processing seems to me same. Simply scenes are done quicker by PS, I would says. Difficult scenes are out of capabilities of HDR SWs. Generally, HDR may be good for lazy ppl with static scenes without any moving objects. Everything else looks bad (for me, maybe enough for most ppl).

[Wheatfield]

Newmikey,

Thanks for the info. I agree that the results from digiKam are generally more natural looking than those from other HDR (or HDR like) software. Many HDR photos have a foreboding, impending doom, look to them. One has to learn to tame that, it seems.

You are talking about tone mapping, not HDR.

[rm2]

I frankly do not understand the difference.

[JeffJS]

We had an office picture taken last week. We have a guy in the office who has been the "official" office photographer for a long time. He posted a preliminary print on the announcement board the next day. When I saw it I was horrified in seeing that the sky was completely washed off. The exposure was challenging but since my newly acquired HDR "skills" I have become more demanding with respects to dynamic range. So, I tactfully asked him if he had bracketed the shot. He said he did. I then asked him if he knew how to merge them into one HDR shot. His look told me that he didn't. I told him that it could be done with Photoshop, but I also told him that I had a program that could probably do a better job. He told me where to find the RAW images and told me to give it a try. The following crops give you an idea of just how much better digiKam did. I cropped out the office people that would have been right below the bottom edge of these pictures, in the shade.

Here is the Photoshop HDR result:



And here is the digiKam HDR result:



There is clearly more detail in the digiKam image. Photoshop produced a 32 bit image file with a lot of room for post processing, but it already had lost details like the ones in the clouds. Now, I know there are probably ways to use Photoshop to manually produced better HDR results. But, I was just testing the tool that most people are likely to use, the automated one.

Oh, and I did this with digiKam 1.5 on PCLinuxOS.

They both look crappy to me. Both are overblown and from what I can see lack any real detail. No one has ever claimed, or at least I haven't seen it, that Photoshop's HDR merge is anything special. You want HDR processing software, use Photomatrix.

[newmikey]

I frankly do not understand the difference.

Very simple, HDR involves making an image with a bit-depth that caqnnot be represented on screen or paper first, the HDR image, and then using a tonemapping operator to bring the bit-depth and dynamic range back to what can be represented on screen/paper. The tonemapping operator is a mathematical equasion.

With the kind of HDR you (and I) do with DigiKam, at no point do you have an image with a bit-depth greater than 8 or 16 and the result is merely a combination of snippets from all blended images with the seams disguised by a clever routine. We'd typically rather call this "exposure-blending" or "pseudo-HDR" while the tonmapping version is called HDR and arrived at by using a program like QTPFSGUI (LuminanceHDR).

[rm2]

Very simple, HDR involves making an image with a bit-depth that caqnnot be represented on screen or paper first, the HDR image, and then using a tonemapping operator to bring the bit-depth and dynamic range back to what can be represented on screen/paper. The tonemapping operator is a mathematical equasion.

With the kind of HDR you (and I) do with DigiKam, at no point do you have an image with a bit-depth greater than 8 or 16 and the result is merely a combination of snippets from all blended images with the seams disguised by a clever routine. We'd typically rather call this "exposure-blending" or "pseudo-HDR" while the tonmapping version is called HDR and arrived at by using a program like QTPFSGUI (LuminanceHDR).

Thanks newmikey. So, let me see if I get this straight. Is the Blending of bracketed images that digiKam does more akin to what one would do in Photoshop by importing a series of images as layers and blending them together using masks? Is there any advantage in using RAW images over straight JPEGs?

[newmikey]

Thanks newmikey. So, let me see if I get this straight. Is the Blending of bracketed images that digiKam does more akin to what one would do in Photoshop by importing a series of images as layers and blending them together using masks? Is there any advantage in using RAW images over straight JPEGs?

Not having used PS I can only translate your question to:
"Is the Blending of bracketed images that digiKam does more akin to what one would do in GIMP by importing a series of images as layers and blending them together using masks?"

You're spot-on. If you look at this GIMP plugin Exposure Blend | GIMP Plugin Registry things will become clearer, I think. PS will supposedly have similar (or even better) plugins.
"exposure-blend makes quick work of blending 3 bracketed exposures into a detailed, realistic, extended contrast image. It has many features to save you the drudgery of assembling contrast blended stacks yourself:

* Set masks from among any of the three images (normal, dark, bright).
* Several smoothing options, including edge protection for halo suppression.
* Stores smoothed versions of all masks used for quick automatic recovery, so you can feel free to experiment with different versions, quickly switching among the mask source and smoothing choices. These are saved along with the file, so you can pick up where you left off.
* Optionally pre-trim the masks' histograms to deliver the most contrast.
* Differencing alignment mode to enable easy manual alignment of the images. This also moves all the associated cached mask to keep things in sync.
* Trim the image to the area of overlap of all three layers.
* Save custom edited image masks for later recovery.

Compared to an automated contrast blending tool like PhotoMatix, exposure-blend has the following advantages:

* Similar "mostly-automatic" mode produces reasonable results (see example below).
* Infinitely tweakable final image, with good real-time feedback.
* Easily change the blend weights in certain regions of the image by directly editing the masks.

Unlike PhotoMatix, the differencing image alignment mode is not automatic, but is very quick, and gives good feedback on the quality of alignment (e.g. residual rotations, etc.).
"

What DigiKam's new plugin adds to the mixture is 2 specialized programs that, simply said, do the aligning and blending much better: align_image_stack and enfuse/enblend, both run from a single GUI interface (the DigiKam plugin).

From their respective webhomes:
"align_image_stack is a command-line tool available in the development version of hugin to align overlapping images to facilitate HDR creation, Exposure blending and extended Depth of Field images. "

"Enfuse is a command-line program used to merge different exposures of the same scene to produce an image that looks very much like a tonemapped image (without the halos) but requires no creation of an HDR image. Therefore it is much simpler to use and allows the creation of very large multiple exposure panoramas.

Enfuse is based on a paper by Tom Mertens, Jan Kautz and Frank Van Reeth: "Exposure fusion" The implementation was done by Andrew Mihal (developer of Enblend) and the hugin team around Pablo d'Angelo

An extended documentation could be found on Enfuse reference manual"

The advantage of using RAW over JPEG is the usual suspect: more bitdepth leads to less noise, banding and artifarcts and eventually to a 16-bit image that can be further tweaked in DigiKam (or similar) to apply some levels, curves and sharpening after the blend. Simply put, higher quality output.

[rm2]

newmikey,

Thanks for that detailed explanation. Sounds good. A lot of it is, at least for me, at this point, more technical that I care to understand. What I do see clearly is what my own eyes tell me. And that is that digiKam gives me some very nice results. I did a test of shooting from inside a very dark room through a window.



This is obviously a very extreme case of contrast. I took a series of 8 shots at different exposure settings. The lightest one is a 3 second exposure.


3 second exposure. by Eye2See, on Flickr

I then blended them all with digiKam's "blend bracketed images" tool.


Exposure blend by Eye2See, on Flickr

I would say that it did a very nice job. It took about 10 minutes (5 minutes to preview and 5 minutes to save). I am happy with the results. And that is, I guess, all that really matters.

For more examples of the results of this tool see this thread in which all the shots are exposure blended with digiKam:

Again in my favorite autumn place