What is HDR?

[GeraldTheMouse]

I've heard people talk about it, and Google didn't really help answer what it is, so I ask you all.

[mjs1973]

HDR = High Dynamic Range. Basically HDR is combining several differently exposed images to get the best parts out of each photo.

Here is a short video that should help explain it a little better. If you do a search on www.youtube.com for HDR, you will find more videos showing you how to create and HDR image.

[another view]

I'm not sure of your experience level, but back in the "old days" with slide film we'd use something called a graduated neutral density (GND) filter if, for example, the sky was a lot brighter than the other areas of the shot. Basically this is a filter that's gray and two stops of density on the top half, clear on the bottom and gradually fades over about 1/2" from one to the other, depending on the filter - plenty of variations out there. This filter plus a polarizer and possibly a warming filter with Velvia was a classic landscape setup.

And it was great until you realized that you didn't have the GND adjusted just right - maybe the gray covered the ground a little bit so there was a dark line, or a small area of the sky wasn't held back by the gray so there was a strangely light colored area near the horizon. Of course this was a week later when you were looking at your film... Go back, wait for more incredible light and shoot again - sigh. (there are tricks to setting the filter properly and it usually isn't much of a problem - usually...)

Version 2.0 was shooting two shots without the GND filter. One was properly exposed for the sky and the other for the ground. Both were scanned and blended in Photoshop - this way you have complete control later with what areas are from which exposure. This is handy if that area isn't a straight line as you'd get with the filter. And in the real world a horizon line is rarely a straight line (other than at an ocean or here in the midwest...). With the GND you'd have to compromise to put that straight line in the best spot but those days were over.

Version 3.0 is HDR, essentially software that takes digital images (two or several) and blends them automatically. Tweak as needed and you're all set.

[fx101]

I'm not sure of your experience level, but back in the "old days" with slide film we'd use something called a graduated neutral density (GND) filter if, for example, the sky was a lot brighter than the other areas of the shot. Basically this is a filter that's gray and two stops of density on the top half, clear on the bottom and gradually fades over about 1/2" from one to the other, depending on the filter - plenty of variations out there. This filter plus a polarizer and possibly a warming filter with Velvia was a classic landscape setup.

And it was great until you realized that you didn't have the GND adjusted just right - maybe the gray covered the ground a little bit so there was a dark line, or a small area of the sky wasn't held back by the gray so there was a strangely light colored area near the horizon. Of course this was a week later when you were looking at your film... Go back, wait for more incredible light and shoot again - sigh. (there are tricks to setting the filter properly and it usually isn't much of a problem - usually...)

Version 2.0 was shooting two shots without the GND filter. One was properly exposed for the sky and the other for the ground. Both were scanned and blended in Photoshop - this way you have complete control later with what areas are from which exposure. This is handy if that area isn't a straight line as you'd get with the filter. And in the real world a horizon line is rarely a straight line (other than at an ocean or here in the midwest...). With the GND you'd have to compromise to put that straight line in the best spot but those days were over.

Version 3.0 is HDR, essentially software that takes digital images (two or several) and blends them automatically. Tweak as needed and you're all set.

Well, I have to say that the GND is not dead. You can combine HDR photography with a GND filter to get a nice detailed sky and emphasize shadow detail. Also, HDR with moving objects isn't a great idea (blurring). Thus, a GND can reduce the dynamic range while still capturing everything in one shot.

[another view]

True and good point - plenty of people still use GND filters with DSLR's and have the shot they want without a bunch of extra steps. This is a good way to work, and a great way to think when shooting. The only problem is that with the GND, you're setting the held-back area at time of exposure. With HDR, you're setting all of that later and can change it as many times as you want.

It's along the lines of shooting in a b&w mode on a digital camera or converting later (or RAW vs JPEG, really) - generally the best results come from the one that takes the most time, but the results may not be worth the extra time. Case by case basis IME.

[GeraldTheMouse]

HDR = High Dynamic Range. Basically HDR is combining several differently exposed images to get the best parts out of each photo.

Here is a short video that should help explain it a little better. If you do a search on www.youtube.com for HDR, you will find more videos showing you how to create and HDR image.

Thanks for the video, it was really helpful.

Fx101/another view - I'll have to think about getting a GND filter; it seems like it would be good for some of the pictures I take.

[Frog]

You can download a free trial of photomatix which I believe is the most used hdr program though it can be done with photoshop if you know what you're doing.
Worth trying the free trial to see if you want/like it. Remember you'll need at least 3 shots; one underexposed, one with correct exposure, and one over exposed. 1 or 2 stops should do it.
free trial at: http://www.hdrsoft.com/

[mjs1973]

The newest episode of Photoshop TV has a pretty good tutorial about using Photoshop to create an HDR image. You can watch it here.

[Mr Yuck]

Here's my how-to on it.

[fx101]

Photomatix generally yields better results, but you can do some great stuff in photoshop though, especially with the more flexible 32bit image processing tools in photoshop. You can generate an HDR with either program, process in photoshop (edit it, that is), then tone map in photomatix.


As for GND filters, they are to be used only in specific circumstances. For example, a sunset shot with a GND filter, HDR or not, will deliver a nice balance of sky detail, a bright sun, and waves. HDR requires too many shots and will blur the ocean and yield a rather odd tonal rendition if the contrast is too much. Also, HDR with a GND filter allows you to view the high dynamic range within the unfiltered portion of the image. This is useful when you have a really bright sky, then have another portion of your scene where you have a variety of shadows for example. Just make sure that it is not a complex scene where the GND would draw "dark" lines where they're not appropriate.

[GeraldTheMouse]

You can download a free trial of photomatix which I believe is the most used hdr program though it can be done with photoshop if you know what you're doing.
Worth trying the free trial to see if you want/like it. Remember you'll need at least 3 shots; one underexposed, one with correct exposure, and one over exposed. 1 or 2 stops should do it.
free trial at: http://www.hdrsoft.com/

Thanks for the link. I just downloaded it, and maybe in the next week or so I'll play around with it.

Mr. Yuck - Great guide, very helpful.