# What is HDR??? How does it work?



## burstintoflame81 (Aug 27, 2009)

I know it stands for High Dynamic Range but is it just 3 bracketed pics and you use software to composite them? Does the software do all of the work or is it much more complicated than that?


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## musicaleCA (Aug 27, 2009)

It's fair to say that it's much more complicated than that. A good HDR can use anywhere between three to...whatever number of images. General rule of thumb is to meter the the darkest area and the lightest area, and then shoot properly exposed images of both the bottom and top of the range, and shots in one stop increments in between. (Sorry if I'm confusing; I'm on the phone too.)


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## c.cloudwalker (Aug 27, 2009)

:smileys:


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## musicaleCA (Aug 27, 2009)

Oh yeah. Too true, eh cloudwalker? I got in with useful advice before it went downhill!


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## burstintoflame81 (Aug 27, 2009)

So essentially its many variations of the same shot...all composited using software? So essentially I was correct, just that it is more than just bracketed shots. So I can adjust the stops and the exposure etc. and just take varying shots and then composite them? Is HDR usually built into most software programs like Corel and Photoshop, or is there a specific program you would recommend? Thanks.


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## c.cloudwalker (Aug 27, 2009)

Right-0-mondo and so I thought you would not mind if, this time, I was the one munching on the popcorn.


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## Ecas32 (Aug 27, 2009)

burstintoflame81 said:


> Is HDR usually built into most software programs like Corel and Photoshop, or is there a specific program you would recommend? Thanks.



i think photoshop might have a plug in that you can use for it but photomatix will be your best bet for software-  HDR photo software & plugin - Tone Mapping, Exposure Fusion & HDR Imaging for photography


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## musicaleCA (Aug 27, 2009)

Photoshop can create HDR's itself, but it's quite limited. Photomatix is alright.

It's not really variations of the same image. What you're doing is trying to capture a range greater than what your camera's sensor is capable of capturing. The HDR post-process isn't strictly compositing; it's more complex than that because it involves tone-mapping.

There are a myriad of other considerations that effect the taking of and HDR image. This includes the fact that HDR processing brings out every aberration in the image, including CA and noise, and adds problems too like ghosting. (Hint: If you don't know what one of those is, you need to learn what it is and the best methods of correcting them before you continue on and create an HDR image.) Your technique needs to be spot-on; there's no room for having any vibrations in the camera (small vibrations between shots, while they might not effect a single image, can soften the resultant HDR significantly), for example.


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## c.cloudwalker (Aug 27, 2009)

Everyone please go answer Josh's question about LDR.


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## burstintoflame81 (Aug 27, 2009)

I probably won't make one anytime soon. I am a total noob, I just like to learn as much as I can so when I do get around to it. I just keep hearing so much about it. Thanks guys.


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