A bunch of us went out shooting Saturday night - almost 10 hours of it. I shot just about every single image planning for HDR, so I shot 7 or 8 frames of every scene, space 1 stop apart.
When I started working on this one I saw a problem for HDR that I just never thought about when shooting - the moving cars were different on every frame. I immediately knew that this was going to be an issue for HDR but I decided to proceed anyway. For one, I wanted to compare the differences between an HDR and non-HDR shot, but mainly because I hate blown-out signs in night shooting. Signs still need to be read, and I can't stand it when they get blown out past legibility in a typical night shot.
8 frames for HDR, each 1 stop apart.
A single frame, the one that I considered the best exposed for this scene, 1 stop darker than the brightest one I shot. (I don't go too bright since I still want to retain the idea that it is a night scene.
As you can see in the first image - the HDR one - the car lights look terrible. They look much better in the second. But compare the "Banknorth Garden" sign, above the billboard. In the single exposure "Banknorth" is tough to read, and "Garden" is blown out to white while the HDR version is much much truer to life and the color of "Garden" is correct. The small logo sign next to "Banknorth" is completely illegible in the single image.
Streetlights and such are fine when they get blown out - it's expected and can look cool on their on. The HDR process certainly gives the lights more definition and crispness, and I do think that even simple lights look better in an HDR version. Compare the greenish light at the bottom center. The HDR shows it quite a bit crisper. Compare the string of lights to the right - the HDR ones actually allow you to see the shape of the bulb while the single image shows just blobs of light. (Yes, it's tough to see the shapes of the light in the small web-sized shot, but they are very clear in the full-sized HDR.)
While I definitely like the clearly-defined lights in HDR I do not feel that the "blobs of light" in the single image are a problem - they're still cool in their own right. There are times when I'd want to see the shape of the bulb, and other times when I don't care so much.
The most surprising thing comparing these 2 shots is the color difference - the HDR version is much duller, while the single image has some nice tones in places. Compare the side of the building under the billboard, and the top right corner of the building above the Banknorth sign. The single image has some nice red tones to it, while the HDR version has gone bland. Checking through the images this color loss seems to happen because the HDR process must tend to average to colors, and in the darker exposures these darker areas were black. So in 8 frames most were black or close, while the brightest 3 show a tinge of red, the red you see in the single image, and some definite reds in the brightest frame.
To test this theory I did the HDR again, using only the brightest 4 frames - the three that showed some red and one darker frame that showed the Banknorth sign clearly without any blowout. This version was much better for color, so I definitely think the HDR process averaged the frames in a way which destroyed the color.
Oh well, live and learn I guess. I like the sign being clear, but I love the color tinges that really make night photography interesting. I'll either have to live with blown signs or weaker colors. We'll see about that.
There is no doubt that the car lights are simply unacceptable in the HDR version, so I won't be doing that again.
