Author Topic: HDR?  (Read 1704 times)

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Matthew

HDR?
« on: October 16, 2015, 08:42:01 am »
Has anyone tired this? (if so, please share:))

Was chatting with a photographer friend last night about it and I'd like to try it. Never have done so before, and not sure what sort of scenes look good / bad with it.

Going to do some experiments where I can, but alas I don't own a tripod yet so images will be subject to what is available for me to rest on.


Offline Samantha C

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Re: HDR?
« Reply #1 on: October 23, 2015, 10:45:25 pm »
Mathew,

I have done a fair bit of HDR there are 2 types of HDR the in camera type and the shoot multiple exposures and combine them type. The other consideration is the software, PS, LR, ...ect there are tons of other SW available.

The in camera HDR is usually single frame, and is generated by the camera software since the dynamic range of the sensor is has far surpassed the sRGB color space used by most displays and printers.  We never see most of what the image sensor was picking up. So in single frame HDR the camera will take the full raw data from the sensors which on most DSLR's is 2 full stops (f) worth and compress it to fill shadow details and highlight details that might have been lost in normal jpeg mode.

Shooting multiple frame HDR (which I guess is what you asking about), is best like you mentioned with a tripod but not always needed if you primary subject is stationary and the shutter speed is high enough.  I just shoot in continuous high usually 3-5 shots 1 full stop apart on one set I will bracket the shutter speed, I will do a second set and bracket the F-stop I will do one at full aperture and the top one at the smallest aperture to keep the shutter speed from having shake. I often just put the camera in manual and do each shots settings myself. Doing both shutter and aperture bracketing in the HDR will let you have some interesting creative control later when you start combining the exposures.  If your camera can use raw I would recommend it as JPEG will make strange artifacts in the combining process that in most case do not work out.

Another photographer introduced me to a little standalone program called Photomatrix they have a trial you can mess with which is actually the fully functional program just leaves a watermark.  I have used it for almost all my HDR stuff that was serious I like the amount of control the software gives and the learning curve was pretty quick.  There's of course Lightroom, and Photoshop HDR filters also and tons of info online for them.

Hope this of use.  I have a ton of other jumble of HDR data rattling around in my head let me know if .....

 :)

Offline Martine A.

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Re: HDR?
« Reply #2 on: November 11, 2015, 01:16:12 pm »
HDR imaging allows capturing images at greater contrast sensitivity than with 'standard' techniques. So called LDR (low dynamic range) techniques.

It is omitting part of story when I describe it this way, but let's say that a standard display is your monitor. It would 'standardly' have three channels Red, Green, Blue, of which each can have intensity 0 - 255 (8 bits per channel). HDR image may have range far greater than that; e.g. 0 - 16383 (14 bits per channel).

HDR image as such can not be displayed on a standard screen whilst preserving all that contrast information. Thus, its contrast range is reduced first to 0 - 255, losing some details and preserving some details. This process is called tone mapping. There are many many ways to map HDR image to a LDR image and achieve from very natural looking photos to very supernatural looking photos.

Like Samantha mentioned, some cameras are capable taking HDR images in a single shot. They are usually [much] more expensive. Another technique, doable with every LDR camera that can change exposure, is:
  • take multiple shots of same subject in different exposures
  • bind those different exposures together to obtain a HDR image. Normally, one will need a tool to do that.*

Whether you are going for one or the other way to obtain HDR images, I recall a free tool named LuminanceHDR, that offers a few tone mapping operators. It can also bind differently exposed LDR photos into a HDR photo. Iirc, it was allowing manual shifting of pictures, thus allowing one to work with multiple exposure photos taken without a tripod. One weird thing about the tool, it seemed to give completely different results when ran on Windows vs Linux.

Hope this helps a bit. :)

* - Keep on mind, the more exposures, the more noise will be introduced to HDR. Thus normally three at -1, 0 +1 EV** are good. Or -2, 0, +2. Sometimes you may decide to go with two: -1, 1 EV. Or -2, +2 EV. Aim for lower (lowest) ISO value when taking photos. Or be ready for more noise, that is.
** - Exposure Value; you should find them with ease in settings! The EV 0 represents the normal setting. A positive value means overexposure (brighter result, but captures darker details of the subject), a negative value means underexposure (darker result, but captures brighter details of the subject).
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Offline Naeree

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Re: HDR?
« Reply #3 on: November 15, 2015, 02:40:56 am »
this is really interesting topic, and new knowledge for me. I use to use HDR preset in Lightroom to make the digital photo HDR. But shooting HDR with camera technique is very interesting. Thank you for sharing

Matthew

Re: HDR?
« Reply #4 on: November 15, 2015, 05:05:27 am »
I've been playing around with different HDR methods since creating the thread, and I feel the one which works best for me is through photoshop, method below a couple example images:




Method:
Shoot an image using RAW
Open the image in Adobe Photoshop
Add one image as -2 , +2 , 0 exposure
Combine the images using the HDR toning feature
Edit contrast, vibrance, clarity ect. to your taste / to suit the image.

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