Photoshop CS2 HDR Feature

[kipper]

Has anybody managed to get this to work with one RAW file but adjusting the EV? Everytime I do mine it keeps saying "There is
not enough dynamic range in these photos to construct a useful HDR image". Any help would be appreciated. I know Adobe says you can't do HDR images this way, but that's bollocks as I've seen other packages do it.

[sirhc55]

Has anybody managed to get this to work with one RAW file but adjusting the EV? Everytime I do mine it keeps saying "There is
not enough dynamic range in these photos to construct a useful HDR image". Any help would be appreciated. I know Adobe says you can't do HDR images this way, but that's bollocks as I've seen other packages do it.

Yes I have done it and posted the results on this forum but have since removed the image. Basically, if you are shooting an image there must be a large dynamic range differential in the first place for it to work.

For example - shoot a sunset every 1/4 hour for approx 8 shots and then try it - that is one method. The other is to shoot a night scene with + and - bracketing and then combine. Essential to this exercise is the need for a tripod.

To make your system work I would suggest duplicating the image 8 times and then do 4 in the + range and then 4 in the - range with the one shot. But, there has to a a large dynamic range difference within the pic for it to work. Also, I would suggest you try multiple shots rather than one shot duplicated.

[sirhc55]

Actually your system won’t work - try reading this:

http://www.luminous-landscape.com/tutorials/hdr.shtml

I knew there was something bugging me about what you were doing -

[kipper]

Actually Photomatix software says while it's not the correct method it is viable and they have an option to do image combining to produce a HDR. For instance bracketed exposure isn't viable for moving images.

[MattC]

Kipper,

Try it with converted jpegs (yeah, I know) and manually entering the exposure values. What is messing up the whole show is HDR's reading of the exif data for those images. There is also no way to over-ride HDR automatically determining exposures. If you can find a way of stripping exif out of your tiff, psd or raw files and manually assigning exposures you would have better luck. The way that I read it (and I have tried) is that there is no benefit in using HDR for various adjustments to a single file. All data that is in the raw file will fit into 16 bits no matter what you do to it (exposure wise) in software.

There are better techniques for what you are trying to do with a single exposure which would probably offer more control. eg a greyscale layer mask with high and low exposures and adjust the brightness/contrast of the mask to suite... or shadow/highlight tool.


Cheers

Matt PS I get what you are trying to do and why.

[sirhc55]

It would appear that Photomatix were not aware of the 32 bit HDR in CS2 as they state that their program does not use masking techniques for HDR - neither does PSCS2.

They also say re a single RAW pic the following:

Can't I just create the exposures from one RAW file?

Not really. That's almost the reverse actually. A RAW file can hold a larger dynamic range than a JPEG output. If you have used only one exposure to capture the scene, your RAW file is already your HDR image.

Converting the RAW file to JPEG images with different exposure levels is like taking several chunks of the dynamic range of the RAW image. Combining back the chunks into an HDR image will at best re-produce the dynamic range of the initial RAW file.

This is what Bigpond has to say re HDR and Lost Coast:

We're getting much closer to having Lost Coast ready to release. Originally planned as a section of the Highway 17 chapter of Half-Life 2, Lost Coast is a playable technology showcase that introduces High Dynamic Range lighting to the Source engine.

Once Lost Coast is released, we will include HDR in our future product releases. For instance, Day of Defeat: Source will feature HDR lighting for all of its levels the day it is released.

One of the fundamental pieces of HDR rendering lies in "dynamic tonemapping." In the Source engine, by varying the exposure of a scene based on how much light is visible, we can accurately simulate a range of brightness that is beyond what a computer monitor is physically capable of displaying. A real-world example of this effect happens every time you walk from a very dark room to an outdoor area with very bright sunlight -- your eye takes a few moments to adjust to the variance in the amount of light hitting the retina. If you have a video card that supports HDR, you'll be able to see this in the engine when Lost Coast is released.

[MattC]

Here is a link to a discussion on the subject: http://www.adobeforums.com/cgi-bin/webx ... @.3bba1306 If the link does not take you straight there search for "HDR Challenge" started by Zane Paxton in the Photoshop forum.

Cheers