"Pseudo" HDR?

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Dieter Mayr
Posts: 453
Joined: April 24th, 2009, 11:47 am
What is the make/model of your primary camera?: Nikon D700
Location: Salzburg / Austria

"Pseudo" HDR?

Post by Dieter Mayr »

HDR seems to be "in" those days, everyone seems to make HDR...
There are also articles of people creating a "HDR"-Image from a single RAW-file, converting it to 3 different exposure levels.
I put the HDR in quotations because I dont think its real HDR.
The RAW file contains the full dynamic range of the sensor, and so would a 16-Bit image converted from the raw file.
So there is no new information introduced if one converts to 3 different images and "HDR's" them.
The same result can be achieved from the 16-bit image with Brightness curve and Masks to protect dark/bright areas of the image (The masks are needed in the HDR process, too).

Am I right with this ? Any comments about it ?
Dieter Mayr

kkopchynski
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Re: "Pseudo" HDR?

Post by kkopchynski »

Hello Dieter,
In all of my reading on HDR I also see the use of a single RAW referred to as "pseudo". A comment is then made that a set of exposures is better. Usually comments similar to the ones you made are given, that is, that no new information is really added. I am often using HDR to capture a sky and a landscape with different brightnesses. If the one exposure has rendered the sky as a featureless white expanse, then underexposing the RAW will not bring back the color and texture that was really there. Also, even when a sky is not involved, I feel that the color and saturation of brighter colors is too easily lost when they end up in the upper portion of the histogram. So I have rarely found rendering an HDR from a single exposure to be satisfying. I think in a couple of cases I fed SNS-HDR a single image and it provided a good base image for some 3-tone adjusting with PWP.

Best regards,
Kevin

JvdW
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Re: "Pseudo" HDR?

Post by JvdW »

Hello Dieter,

I use ACDsee Pro for RAW conversion. This program has a module called 'lighting' wich has a very intuitive interface to recover shadows and highlights to an extend that exeeds the normal recover functions because you can apply it to a limited tonal range. The result can be quite similar to a HDR image, I often get questions if I used multiple exposures and HDR software to get certain pictures. Off course the image doesn't contain more information than the dynamic range of the sensor, but somehow the image does create the illusion of a larger dynamic range.
The function is said to use a local contrast algorithm, but ACDSystems is very vague about it. It might be similar to what you describe; brightness curves and masks, but applied to the RAW data.

Off topic: In my opinion ACDSee ist great for RAW conversion and DAM but its editor is very limited

John

aloomens
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Joined: April 25th, 2009, 4:50 pm

Re: "Pseudo" HDR?

Post by aloomens »

I think with a single RAW file, you are not so much using HDR techniques as you are just Tone Mapping (either automatically or manually as you mentioned). A RAW file can contain more dynamic range than a JPG, so tone mapping a single RAW file can work well in some cases. I have used SNS-HDR Lite to process single RAW files and have been pretty pleased with the results in some cases. SNS-HDR seems to be much more leaning toward the realistic side of HDR rather than the exaggerated, painting type effects. Since SNS-HDR Lite is free, why not give it a try.

To use it, I just created a shortcut to the program with the following parameters "-dd -da -srgb -default" Which basically says don't do de-ghosting, don't align images (since theres only one), use srgb, and default tone mapping. Drag and drop a RAW file on the shortcut and it will create a tone-mapped jpeg file.

I know there are some other posts on this forum about using SNS-HDR with PWP (which is where I first heard of SNS). Try searching, or if some one knows, perhaps they can proved a link here.

kkopchynski
Posts: 16
Joined: April 26th, 2009, 2:46 pm
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Re: "Pseudo" HDR?

Post by kkopchynski »

You might also want to add -tiff16 to that command to get a 16 bit image if you want this. It used to default to jpegs but I have not checked the behavior in the latest version.

-Kevin

Dieter Mayr
Posts: 453
Joined: April 24th, 2009, 11:47 am
What is the make/model of your primary camera?: Nikon D700
Location: Salzburg / Austria

Re: "Pseudo" HDR?

Post by Dieter Mayr »

Kevin, John, aloomens, thanks for your contributions.

I will give SNS-HDR a try when dealing with multi exposure HDRs.
For a single exposure, converted to a 16-bit image, I find all tools to tickle out all information abailable in the image in PWP.
Im not a big fan of having a special tool for this and that, if i can achive the same with a single program, and i like doing things "by hand", to know what to do, to turn a little here, turn a little there till it looks like i want to, and not leave it all to a automatic, but this is of course my very personal workflow.
Dieter Mayr

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