HDR

[Stutterbug]

I'm still very new and this picture is by no means pro but it's I feel it's a steep in the right direction. Don't mind the text as this was used for my Geography class. Let me know what you think good or bad. It was done in Photomatix

[Stutterbug]

wow that looks terrible after the resize...

[tonydee]

Was the sky really that much bright that you needed to use HDR? If so, I guess you've done ok, because it the sky/ground balance doesn't look that unnatural, making it look like the dynamic range didn't require HDR at all. I fancy I can see a little lightening of the sky right beside the land... (sometimes the eye can play tricks though, and I haven't checked using a colour sampling tool). Perhaps post a couple originals so we can see what you've achieved...? Cheers, Tony

[Bill Boehme]

Was this done using a single image to create a faux HDR? It looks like it might be a single image HDR because the foreground details are very noisy. I agree with Tony about the prominent halo in the sky.

[Stutterbug]

It was done using AEB to take 5 different stops. This is not the exact original but the same settings were used on this one. 28mm, f6.7, 1/1000. I'm curious since my focal was 28 does that mean I should have been at a shutter of 1/280 as per the rule? Then adjust my F/iso accordingly?

Tony-
Was the sky really that much bright that you needed to use HDR? No, I wanted to make an HDR image, but as it was the foreground seamed very dull so I wanted to bring up the color there.

Thanks for the input.

[Stutterbug]

and yes the lens was dirty lol

[Bill Boehme]

I'm curious since my focal was 28 does that mean I should have been at a shutter of 1/280 as per the rule? Then adjust my F/iso accordingly?

I think that you might be misinterpreting the "rule". It is not really a "rule", but just a guideline on avoiding blur due to camera shake -- and going by that guideline, any shutter speed of 1/30 second or faster is normally sufficient if you have a reasonably steady hand. Since you used 1/1000 second, you would not have a problem with camera shake even if you had a dozen cups of coffee beforehand. The time to be concerned about the rule is when the light is very low and results in a very slow shutter speed -- for instance if your shutter speed had been around 1/10 second, then it is very likely that you would have had some camera shake.

[CJinAustin]

I don't think the original image was outside of your cameras dynamic range... meaning the same image probably could have been produced with a single image and some contrast adjustments.

[tonydee]

As CJ and Bill mention, you don't need HDR for this. HDR - High Dynamic Range - refers to scenes where the brightest and darkest points can't be adequately captured by the camera in a single shot. This is the histogram of the photo in post #5 above:

359737

The curve here represents the area in the photo that has the level of exposure shown in the black-grey-white gradation bar at the bottom. Clearly, the darkest parts of the picture are still far above black, and the brightest parts nowhere near white. So, your scene simply isn't a high dynamic range scene. Taking multiple exposures and making an HDR image buys you very little: it's like using a suitcase for a wallet when you've only got a few yen on you anyway.

You should either expose to the desired target level for viewing or printing (for convenience), or expose to the right (bright but not quite overexposed/blown/clipped) and reduce brightness in post-processing (for optimal quality). Then you can apply local contrast enhancement - as CJ points out - to get a punchier look.

FWIW, true HDR requires some mapping from the larger dynamic range captured back to the dynamic range (aka contast ratio) of the display device... this is called "tone mapping". It's this look you seem to want, but it's only associated with HDR due to the necessity of its use for rendering such images.

Tone mapping is weird: for pixel data that is too bright to display, it starts by trying to display the brightest pixel of that colour that it can, but then if there's an even brighter pixel nearby, it darkens the former pixel so the viewer can see some gradation between them. This kind of logic flows organically around the image (many variations on the algorithm exist), trying to keep areas that had distinct intensities distinct, but trying not to change the intensity further from the display devices best representation than necessary. I wish I could think of a good analogy to make it easier to understand... will think about it.

Cheers, Tony

[stathunter]

wow that looks terrible after the resize...

whoa.....yes it does. dunno what happened with it.

[Walkingmanblues]

Hope you don't mind, just tweaked the levels and curves a bit for practice.

[Stutterbug]

No I don't mind at all and that helps me understand a lot. Your image looks a lot better than mine without the HDR stacking which ties in exactly to what Tony and CJ were saying. So then a good time to use HDR would maybe be if I had a picture that if I took it with correct exposure either the white or blacks would be blown out? Therefore requiring that I take many pictures to capture the blown out spots then stack them all. Am I on the right track here? Example maybe a Black crow against a very bright sky?

The very little bit of HDR's that I have seen have always looked great with saturation and different highlights of color which is what made me want to give it a shot.

Thanks for the clarification on the rule there Bill. And thank you everyone else for taking the time to CandC this. You have no idea how helpful this is to me and I appreciate it.

[tonydee]

So then a good time to use HDR would maybe be if I had a picture that if I took it with correct exposure either the white or blacks would be blown out? Therefore requiring that I take many pictures to capture the blown out spots then stack them all. Am I on the right track here? Example maybe a Black crow against a very bright sky?

That's the idea :-). The camera doesn't actually sample colours directly, it samples red, green and blue components, so actually any of these primary colours can be blown out independently or in combination. All that means is that overexposure can sometimes be in coloured area of the photo, and not only a white or off-white one. And just an FYI - the term "blown out" is used for over-exposure, but not under-exposure.

The very little bit of HDR's that I have seen have always looked great with saturation and different highlights of color which is what made me want to give it a shot.

There's a dedicated HDR forum here on POTN... if you want to see lots more and the types of scenes it's applied to, could be a good place to start. The tone-mapping can certainly produce a very impressive result, and I certainly remember being gobsmacked the first couple times I saw good HDR images, though it lost its novelty value a bit like my 8mm fisheye did ;-).

Cheers, Tony

[Bill Boehme]

So then a good time to use HDR would maybe be if I had a picture that if I took it with correct exposure either the white or blacks would be blown out?

Almost correct. The ideal situation for using HDR would be if BOTH highlights and dark areas are clipped with a single exposure AND there is useful detail in either that requires a wider dynamic range to capture.

Strictly speaking, dark areas aren't "blown" (that only happens when highlights overload the sensor), but the number of luminance levels available to convey details in the darkest areas are insufficient to reveal fine details.

There is normally not a great deal to be gained by making a large number of exposures. About three to five exposures at 1 to 2 stop increments is more than sufficient. Capturing a wider than necessary dynamic range is counterproductive since it means that the desired segment of dynamic range is just getting squeezed into a smaller segment of the overall captured dynamic range.

[tonydee]

The ideal situation for using HDR would be if BOTH highlights and dark areas are clipped with a single exposure AND there is useful detail in either that requires a wider dynamic range to capture.

I think I know what you mean, and it's right, but I think that's a confusing statement. If the scene has a wide dynamic range you want to capture, and you simply centre the camera's exposure level to capture the middle of that range, then both highlights and dark areas would be clipped and compromised.

But, an intermediate photographer is likely to start by exposing to the right, so highlights are not blown, then looking at the histogram and seeing clipping at left, realise:
- in darker parts of the image where only a little "signal" is captured, the camera's noise will compromise the quality
- even darker parts won't record a signal at all... only noise

So, seeing that "exposure to the right" isn't capturing shadow detail adequately is also a good litmus test of a need for HDR, even though blown highlights were never an issue.

And an advanced photographer, or one who's read about scenes needing HDR, often looks at a scene and correctly concludes "this needs / would benefit from HDR", without needing to see a histogram first.

Regards,
Tony

[Bill Boehme]

Thanks, Tony. When I reread my statement this morning, I immediately decided that was not quite what I intended. I appreciate your effort in keeping me honest.