HDR with one RAW?

[Trigger]

I read somewhere how one can make an HDR from one RAW file by increasing the exposure on one, decreasing on another, then combining the three for an HDR. I just tried this (saving them all as JPGs as well as TIFs) and it wouldn't work. Both the HDR Pro in PS and HDR Efex in NIK wouldn't do it. What am I doing wrong or missing?

 

[480sparky]

You can't increase the dynamic range captured in one image. If the range of the scene is within the range of the sensor's capabilities, there's no need to do HDR. If the scene's dynamic range exceeds the sensor's capabilities, you can't magically pull details out of pure black shadows and/or blown-out highlights in a single image.

 

[thetrue]

Thanks for that explanation sparky, I was wondering the same thing

 

[Trigger]

Are you sure? I think I read that this is possible numerous times (and hey, if it's on the internet it must be true right? - LOL).

Again, I opened the RAW file in PS Camera Raw, increased the exposure by 1, saved that file as a separate TIF (and JPG), then opened the RAW again, decreased the exposure by 1, saved it as a separate TIF (& JPG), and also saved the neutral RAW as a separate TIF (& JPG).

So those three files won't work as a foundation for creating an HDR?

 

[thetrue]

Why not try changing the exposure more, like +/-3 or something more drastic?

 

[480sparky]

Are you sure? I think I read that this is possible numerous times (and hey, if it's on the internet it must be true right? - LOL).

Again, I opened the RAW file in PS Camera Raw, increased the exposure by 1, saved that file as a separate TIF (and JPG), then opened the RAW again, decreased the exposure by 1, saved it as a separate TIF (& JPG), and also saved the neutral RAW as a separate TIF (& JPG).

So those three files won't work as a foundation for creating an HDR?

The result would certainly look like an HDR, especially if you pushed the process to the 'cartoon' level. But if the data in the shadows or highlights just isn't there, adjusting the exposure slider in post is only going to create a sick gray.

 

[Trigger]

I think I just figured it out. In NIK HDR Efex, the 3 images open up with an alert that all of the exposures are the same, but if I manually adjust the values for over exposed and under exposed ones, then it works.

 

[480sparky]

I think I just figured it out. In NIK HDR Efex, the 3 images open up with an alert that all of the exposures are the same, but if I manually adjust the values for over exposed and under exposed ones, then it works.

How about a screen shot of the histogram?

 

[thetrue]

And the result is.....?

 

[Trigger]

How about a screen shot of the histogram?

I know nothing about histograms, so I'm all ears.

 

[Trigger]

And the result is.....?

It's tough to tell as this is such a crap image to begin with. I may try another, and will report.

 

[Trigger]

It appears to work, although I don't have any RAW files that would be a good acid-test for this. Sparky may indeed be correct, but perhaps you guys might want to try it out; let us know.

 

[christop]

You cannot display or print an HDR image directly without somehow decreasing its dynamic range. This basically means you have to "compress" the brightest highlights and darkest shadows so they can both be displayed or printed on a low-dynamic range medium such as a computer monitor or paper.

One method to decrease the dynamic range is to decrease the contrast of the whole image, which generally results in a flat image. Another popular method is tonemapping, which also decreases the contrast of the whole image but attempts to maintain local contrast--that is, tones near each other maintain their relative brightnesses. Other methods attempt to mimic the way the eye sees tones in a scene, which often result in more natural images.

With only one raw image, you have only a low dynamic range, so it's not HDR. You can still tonemap it as if it were HDR using the technique you described, though.

 

[480sparky]

How about a screen shot of the histogram?

I know nothing about histograms, so I'm all ears.


View attachment 30493

You haven't even reached the dynamic range of the sensor. No HDR is needed. You just need to adjust the black and white points

 

[Trigger]

Ahh, ok, thanks christop.