PDA

View Full Version : Issues creating HDR images


4 low
03-17-2006, 06:37 AM
I'm trying to take a series of RAW images of a reflective sphere, and merge them into one HDR image using photoshop, but have come across a problem.

When in photoshop, using the Automate > Merge to HDR command, and then after merging the selected images, I get the following image:
http://img93.imageshack.us/img93/848/bmwhdrtest010cb.jpg (http://imageshack.us/)

That's the final output after merging files. This image is then saved out as a .HDR. The image mode is set at32 Bits/Channel. But if I try to open the file I just created, I get something that looks like this:
http://img93.imageshack.us/img93/3770/bmwhdrtest025rq.jpg (http://imageshack.us/)

I'm very new to creating HDRIs from bracketed photos, but with my limited experience in this process, I've never had this problem before. Does anyone have any suggestions as to what might be causing this to happen? What is causing the magenta to fill up the image, and how do I fix this? I've tried three seperate image sequences and all have had similar results. Is there a setting in Photoshop I'm missing? Like I said, I've created these types of images before with no problems, this is the first time I've seen anything like this.

Thanks in advance.

SoLiTuDe
03-18-2006, 06:05 AM
I've had no experience doing it with photoshop, but how many exposures do you have? I'd suggest getting HDR Shop (http://www.debevec.org) (free) and using that... i've had good experiences with it.

4 low
03-18-2006, 04:25 PM
There are 6 exposures. I've tried HDRshop and get the same results.

4 low
03-21-2006, 03:07 PM
After messing around with it for a while, I was able to come up with something that seems to have worked, or at least helped.

What I did was take the raw files from the camera, and open them in Photoshop. I increased the temperature of each raw file, then saved each image out as a .dng file. Then using Photoshop's Merge to HDR, put each image together to produce a result with no magenta or other artifacting. That seemed to work, if anyone ever comes across this in the future, hopefully it'll be of some help...

lehthanis
03-21-2006, 03:16 PM
I always thought that color anomalies in HDR formation came from registration issues...whereas the image sequences don't line up properly and confuse the HDR calculation process.

4 low
03-21-2006, 04:20 PM
If that's true, that would be some great information. I really want to know why these color variations are occurring so I can prevent them in the future, and that would definitely be a huge help if true...



In Photoshop CS, there's an aligning option that you can check to allow Photoshop to automatically align each image when merging to HDR, which I have always used. Even with the camera on a tripod, I've noticed very sublte movements in the images before, and Photoshop has generally been very good at aligning everything, so it's difficult to say that the images were misaligned. But at least now I have something to test... when I get a chance, I'll take a series of images that I know works, and purposely misalign them and see what happens....

lehthanis
03-21-2006, 04:39 PM
I know that aligning the images is very important...whether or not that was your particular problem is a different story, but its something to think about anyways.

CGTalk Moderation
03-21-2006, 04:39 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.