HDR photos

[epicstruggle]

Nice set of photos taken around/in manhattan. Quite nice:

http://www.flickr.com/photos/automatt/sets/72057594091674928

 

[London Geezer]

HDR photos?

I thought all pictures already had a pretty high dynamic range?

Oh god, i have to buy a new camera don't i....

 

[epicstruggle]

HDR photos?

I thought all pictures already had a pretty high dynamic range?

Oh god, i have to buy a new camera don't i....

I think the trick has to do with exposure settings (et al), although im not a photographer so i could be talking out my wazzoo!
sample:

 

[[maven]]

More here. HDR is all his fault!

 

[London Geezer]

Mmm that's more to do with photoshop than exposure.... All in my very humble opinion.

 

[Jabbah]

Yeah, my dad is getting into this digital photography lark and one of his books goes into this type of photography where you take multiple pictures with different settings and filters and then compose them together in photoshop to produce a "HDR" image.

 

[zsouthboy]

HDR photographs are 2 or more pictures with different shutter speeds, combined so that the image data is compressed across the dynamic range, enabling you to essentially "see" two or more pictures at once.

I've taken my fair share of HDR pictures. (Use your bracketing feature on your camera, set a stop or so apart, then merge in photoshop)

 

[KimB]

Actually:
http://www.flickr.com/photos/automatt/sets/72057594079498133/

Gah, zsouthboy beat me to it.

 

[LeGreg]

I thought all pictures already had a pretty high dynamic range?

Sure, the entire world is displayed through your eyes with no limitation in range, and a granularity of a few photons. But your camera typically has a limited range and precision (they don't make cheap HDR cameras.. yet).

Oh god, i have to buy a new camera don't i....

The idea of the photomanipulation is to take several photos with traditional cameras : usually they are limited to 8 bits per channel fixed range jpeg output, some higher end models have a 12 bits RAW output (not strictly equivalent to a HDR image though). But if you've got time on your hand (non moving subject like a landscape) then you can take several pictures with a different exposure range. Then you recombine them with photoshop or some more clever program like photomatix.
http://www.hdrsoft.com/

Note that those pictures shown above are not very subtile in the effect (color saturation overblown) and they show some strong haloing artifacts. (well once everyone will know how they are done, people will get tired with the effect )

LeGreg

 

[KimB]

Sure, the entire world is displayed through your eyes with no limitation in range, and a granularity of a few photons.

Neither of those statements is close to correct. Granularity is small, yes, but your receptors are still cells, which are vastly larger than photons. And the dynamic range of the human visual system is most certainly limited.

 

[zsouthboy]

Our eyes and brain resample the world around us in amazing ways.

Did you know that you can't see color, other than in your peripheral vision? You brain "fills in" that data for you.

EDIT: Duh, that's wrong. Thanks Chalnoth. I didn't get much sleep. Wee! Coffee!

 

[KimB]

Er, that's not true. The greatest color sensitivity is in the center of your vision.

What you're probably thinking of is the blind spot where the optic nerve connects with the back of the eyeball which our brain fills in so that we hardly ever notice it.

 

[Captain Chickenpants]

Luminous landscapes has quite a good explanation of the technique, and when you would use it.

http://www.luminous-landscape.com/tutorials/digital-blending.shtml

Here is one of my shots using the technique a little differently.

 

[DOGMA1138]

in photographs HDR is achived basicly by photographing the same sence in diffrent exposure settings i.e -4 -2 0 +2 +4 when 0 is you're default exposure settings. and then you blend those pictures using a tone mapping algorithem. the more exposure levels you caputre the "better" effect you get.

 

[KimB]

Er, that's not true. The greatest color sensitivity is in the center of your vision.

Just thought I'd dig up a source for my statement above:
http://en.wikipedia.org/wiki/Visual_system#Retina

Rods are found primarily in the periphery of the retina and are used to see at low levels of light. Cones are found primarily in the center (or fovea) of the retina. There are three types of cones that differ in the wavelengths of light they absorb; they are usually called short or blue, middle or green, and long or red. Cones are used primarily to distinguish color and other features of the visual world at normal levels of light.

(emphasis mine)

 

[nutball]

I've taken quite a few of these HDR shots (I started back when I was shooting film and it was a PITA, digital makes it much easier of course). It's a very clever technique and all but I can't help feeling that the results can be a bit "flat" if not done properly.

Fundamentally what we're doing is HDR capature and LDR display. So until someone invents high dynamic range printer paper the results are going to remain difficult to access.

Interestingly there was a CCD design which used two different sizes of pixel to achieve essentially the same result in normal use with a single exposuse (though less dynamic range than is possible with multiple exposures of course).

 

[Mariner]

Interestingly there was a CCD design which used two different sizes of pixel to achieve essentially the same result in normal use with a single exposuse (though less dynamic range than is possible with multiple exposures of course).

I seem to remember reading about that somewhere a year or two back - a Fuji design IIRC?

I like the look of these HDR images - some of the Manhattan shots look almost like some images I've seen generated in Bryce!

The only thing stopping me trying something similar is the lack of a decent digital camera and the lack of a tripod!

 

[chavvdarrr]

Guys, why don't you buy a real camera and get "hdr" photos immediately?
You know these crappy, shitty, analog things ... like "Leika" ...

 

[Jabbah]

Guys, why don't you buy a real camera and get "hdr" photos immediately?
You know these crappy, shitty, analog things ... like "Leika" ...

And take multiple pictures, then wait to get them processed and printed and cut them out with a craft knife and stick them back together But seriously, one picture would give you a Higher DR image than a digital one but not the effect desired.*

Essentially there is no HDR in any step of this technique. You take a bunch of LDR photos with different exposures and then stitch them together into another LDR image. You end up with an image that has different exposure settings for different regions, not a HDR image. You could do the same with a HDR scanner and a good photograph by scanning it in and then masking regions and changing the brightness / contrast / gamma of certain regions to bring the whole image into a lower DR.

*[Edit] Nutball metnioned doing these types of images with film so it must be possible, but how?

 

[KimB]

Er, this technique applies to "classic" cameras just as well as digital ones. It's just harder to do on an older-style camera.