HDR/CS2 help needed.

[Mcphisto]

Does anyone know why, when I put three images into CS2, all at different exposures, but taken from the same RAW photo, try merging to HDR, it goes so far as to nearly finish producing the final result before a box appears saying "There is not enough dymanic range in these photos to construct a useful HDR image"??? The picture is of a mountain, lake, stormy clouds etc. Really confusing.

Many thanks:thumbsup:

[Medley]

This is the short answer version- let me know if you have questions.

When you capture an image with a digital camera, the information in the image is not distributed evenly. 50% of the total information in the image is captured in the lightest range, 25% in the next lightest range, and so on.

It is this distribution that the computer is looking for when merging to HDR- not the lightness levels in the photo. The computer takes from each image the area with the most information, and combines them to create an image with the maximum information in EACH lightness range.

Simply adjusting the exposure on a RAW image does not change the way the information was distributed when the image was taken. As far as the computer is concerned, you're still giving it three identical images. Even if it program did merge them, you would be disappointed with the results. Essentially, you would get the same image back- possibly with a slight Levels adjustment.

Here's a thread that explains things in a little more detail. You might find it helpful: HDR questions

Hope this helps!

-Joe U.

[Mcphisto]

Thanks Joe that helps alot! I was only taking the short route (1xRAW and adjust in CS2) as I take my 15 month old with me and setting up a tripod is out of the question! I will have to find the time to do it properly somehow I am a bit confused by the tutorials Ive seen on the web saying you can do a hdr pic from one RAW image. How do they manage it?

Thanks once again for taking the time to explain this for me. :thumbsup:

[redonnemoi]

i am too poor to buy CS2 right now tho

so may i ask is there a way to do an HDR merge in Photoshop 5.5? Is there downloadable plugin or something like that.

Also, I gather from reading other people's websites that the required ingredients for an HDR image are: 3 photos at 3 different exposures, one over, one good exposure, and one over?

thank you.

[HowLowCanYaGo]

If you can't afford CS2, then download a program called photomatix. It is lik $60 and does a much better job at tone-mapping than CS2 can.

[gahspidy]

McPhisto, you may want to consider purchasing Photomatix as well as it allows you to create an HDR type image from one picture as you were trying to do.The results I've seen are not quite as good as a true HDR with multiple exposures, but the results are still quite impressive.