Why is my HDR image oversaturated and look negative inverse in highlight areas?

Question

I wanted a photograph of Times Square. It was my first time using HDR. So, I took into consideration about exposure compensation for an even exposure. I set my camera with mirror lock-up, and self timer to reduce vibrations and increase sharpness of the image. I used AEB (Auto Exposure Bracket) shots in 2 stop intervals (-2,0,+2). I did a little tweaking to make the look how I wanted, but this negative and over-saturated fill in some of the highlighted areas which looks clearly fake as you can see in the full image and the close-up image. It's very clear in the lettering Ford and red back-lights on the cars.

Full Image:

Close-up 100%:

Camera Settings:
1/320 sec
ISO 800
f/11
24mm (24-105mm f/4L IS USM)

Is it due to the light flickering between shots or too bright or the processing of the three images merging together incorrectly? How do I compensate for this or what can I do the next time to prevent this from happening and result in a natural even exposure image using HDR?

Answer 1

Software have trouble when there is motion in the scene to merge into an HDR image or even perform Exposure Fusion. There are two ways to deal with this:

1. Increase your odds by shooting multiple brackets or multiple of each frame in a bracket.
2. Take longer exposures. This is particularly needed for fluorescent lighting which cycles in north america at 1/60s (60Hz). Aim for at least 1/60s in your fastest shot, so 1/250s the the metered exposure and therefore 1/1000s for the third, assuming +2 EV steps.

The result will be quite different artistically but you can take option 2 above to the extreme using a very long exposure, something like 2, 8 and 30s. There will be more motion during frames but it will blur a lot and sometimes makes the results easier to merge. For such a dynamic scene as time-square, I would try to get quite a few sets and look at the results to decide which ones are worth processing.

Answer 2

Most of it appears to be related to your shutter speed of 1/320 second. Presumably the +2 shot was at 1/80 and the -2 shot at 1/1250. At least the shorter two of these three shutter times are likely faster than the flicker rate of the lights used on the advertisements and even in the tail lights of many of the cars as LEDs become more ubiquitous. When dealing with flickering light sources the conventional wisdom is to use a shutter speed slow enough to capture one full cycle of the lights.

The "fake" look of many of the bright light sources may also be related to oversharpening of the individual images before combining them. Or it could be due to oversharpening local contrast within your HDR application. Without knowing the particular application and method used to combine the images, it is hard to say. But many times it helps to apply less sharpening to the individual images before combining them when using a method that increases local contrast to bring adjacent dark and bright areas closer together.

Answer 3

Some hdr software will have problems if even the darkest shot is overblown in some areas. In that case, increase hdr range or shoot more shots.