HDR - how to fail

[wossname]

My first attempt - this is my back yard generated from three exposures, (-4, 0, +3).

Conclusion: HDR is hard to do.

Although this is probably attributable to poor choice of subject. Apologies for any feelings of nausea brought on by looking at this...

Arrrgh! the green it burns... it burrrrrrnnnnsssss!

(the original 0 exposure is attached second ,for comparison)

[wossname]

But it's fun to play with and it does salvage areas of a scene that would otherwise be lost to the dark side (see the plants in the top left).

I did try photomatix but that didn't give me much better results, supporting the theory that the scene wasn't ideal for HDR.

[Arrow_Raider]

I tried to do HDR once. I was confused in the attempt and failed. My first issue was that I am not sure if I was even adjusting the exposure level. I had to hold a button and scroll a wheel to change a number from 0 to +something or -something. The range was limited to -2 to 2. Is that normal?

[wossname]

-2,0,+2 is normal yeah. I supersized mine though .

[schoolbusdriver]

I had to hold a button and scroll a wheel.....

Check the manual to see if your camera has AEB (Automatic Exposure Bracketing). You can pre-define the exposure limits then "point and shoot" 3 exposures.

(One thing I've learned recently, don't put a polarising filter on the end of a telephoto lens.)

[mendhak]

D40s don't do auto bracketing unfortunately. This might be a trend - maybe developers just suck at HDR. But from all my failed attempts, here's what I've noticed

1) Landscapes are the easiest - things nearby are going to be tougher.
2) High contrast scenes work - so if there are clouds in the sky, that'll help. Shadows in the area too.
3) I usually take -3,-2,-1,0,1,2,3... 7 shots.

Take this advice with a bucketload of salt, because I've only had one semi-successful photo in HDR.

[penagate]

I think it is a trend — my attempts have all failed miserably.

[penagate]

(One thing I've learned recently, don't put a polarising filter on the end of a telephoto lens.)

Why not?

[schoolbusdriver]

It messes up the auto focus at anything much over 30 feet. I've tried with linear and circular types.

I suppose I could resort to manual focusing...

I'll have to try it while using "Live View". Other than that it's PSP.

Any tips would be much appreciated.

[penagate]

Linear polarisers will not cooperate with phase-detection AF but you should be fine with a circular one.

[EntityX]

I don't have much of a camera now, just a Samsung Digimax 530. It probably doesn't have the feature you guys are talking about but what is HDR. If you use mutiple exposures do you have to keep the camera in the exact same place and shoot at the exact same angle?

[penagate]

In short:

Dynamic range is the range of luminance values in a scene: the contrast between the darkest and brightest points of the scene. A scene of uniform lighting and a bland subject will tend to have a low dynamic range whereas a typical outdoor scene lit by the sun will have a higher dynamic range.

A camera cannot capture anywhere near the same dynamic range as the human eye and neither can print or digital display mediums display it — meaning that information in the scene is usually lost. (Like that last disappointing photo of a beautiful sunset that you took.)

A high dynamic range (HDR) image is produced by taking multiple exposures of differing lengths and combining them to produce a composite image with effectively an expanded dynamic range more similar to that of eyesight.

Since this image cannot be rendered in digital or print mediums, its dynamic range is compressed to fit the luminance range of a standard image. The compression must be controlled manually in order to both preserve luminance information in the scene and maintain a realistic tone (else you end up with freaky results).

Although the resulting image is often termed 'HDR', this is not technically correct since compression results in an image of normal dynamic range.

[wossname]

It is HDR if you use RAW files (I convert mine to non-compressed TIFFs before I start working on them) and then only convert to jpeg after the final result is achieved.

But yeah if you work on jpegs throughout then as pena says, it's not proper HDR, nor would the results be worth a damn.

[Arrow_Raider]

else you end up with freaky results

This, boys and girls, is your mind on acid.

[wossname]

Yeah, hydrochloric.

[EntityX]

The picture in the freaky results link(post #12) doesn't look like a photo at all. The buildings look like they were painted. If that's a photograph of that scene then that really is a freaky result.

[wossname]

True - but there are actually no real defects in the image itself. It has a fairly continuous effect. Some (exaggerated) HDR techniques have unpleasant contrast deficit effects that can leave strange areas of black or white in the middle of noisy contrast regions.

HDR can be overdone well (see post 12) or overdone badly (see the OP).

[penagate]

It is HDR if you use RAW files (I convert mine to non-compressed TIFFs before I start working on them) and then only convert to jpeg after the final result is achieved.

You can make a HDR image from JPEGs. RAWs do have more luminance information but not enough to be called "HDR".

Photoshop stores HDR images in a specific format which can't actually be rendered as is. You do get to open it and view it at different points in the exposure range though using a slider.

Making a HDR image is the simple part; compressing it is where you can get the interesting results.