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HDRI With Adobe Photoshop CS2

Camera Raw and script make it a snap By Stephen Schleicher

For anyone doing 3D work or compositing for film, using 32-bit images for light probes and exact light interactions is vital.  The ability to create HDR images has been somewhat difficult to achieve with some other software out there, but with Adobe Photoshop CS2 its as simple as 1, 2, 3. 

Before we jump into it, you may be asking, "Hey, Photoshop CS2 has been out for a while, why are you showing this to us now?"  Well dear reader, it wasn't until the release of Adobe After Effects 7.0 with 32-bit support that this became a much needed feature for compositors, animators, and motion graphic artists.  So this is really more of a tutorial for AE users than Photoshop and photography experts.

The basic idea behind HDR images is you capture your subject across a range of f-stops or shutter speeds, then align the images and compile them into a HDRI format.    The first step then, is to find a subject to shoot.  For this exercise, I went down to the local university and took some morning shots of a fountain.  This image has very bright and very dark areas, and getting a perfect exposure across the entire image can be difficult.

TIP:  Even though Adobe Photoshop CS2 can align the images during the compiling process, it will save you time and stress to use a tripod when shooting.

Photoshop can use Camera RAW and JPG to compile a HDR image.  It depends on your style of shooting, my camera will allow me to capture both RAW and JPG in the same shot.  Most professional still photographers will probably be shooting RAW.

Before you begin make sure you download the latest Camera RAW plug-in from the Adobe website (www.adobe.com).  Im using the Canon new EOS 30D that uses the new RAW format.

Like many cameras, the Canon EOS 30D uses a numbering system that doesnt really reveal much about the image shot.  There are two ways you can use Photoshops Merge HDR script.  The first works through Photoshop (File>Automate>Merge to HDR), but only lets you work with file names.  The other, and easier method is to open Photoshops Bridge and navigate to your image directory.

Select the images that comprise the f-stop range for the subject you shot, then from the menu, select Tools>Photoshop>Merge to HDR.

Depending on the speed of your computer, it could take a few moments to several minutes for the images to open and compile.  This is so much better than many of the older applications that were used to compile HDR images that took quite a bit longer, and quite frankly, were difficult to use for many users.

Once the files have aligned themselves, Photoshop will ask you to set the white point for the preview image.  This does not effect the final file, just the initial setting for you to see the image.

Click OK, and Photoshop will begin to merge the images to the final HDR format.

If you didnt use a tripod when shooting, or if you were pressing the shutter button, you may have introduced slight camera shake, which results in a blurry image, that just doesnt cut it.  If you use the File>Automate>Merge to HDR method, there is a check box that you can turn on that allows Photoshop to attempt to align the images.

This solution works very well, but be aware it drastically increases the time it will take to compile the HDR image.

No alignment is on the left, auto align is on the right.  This results in a much better picture.

Thats all there is to it.  But where do you go from there?  With a HDR image, you can further refine and adjust the exposure of the image using many of Photoshops effects and filters.

But be aware that not all of the filters and image controls are available for this type of image because they are not 32-bit compatible.  Nor will you be able to do much image manipulation as many of the tools are not available for this format.  Still, there is more than enough control to adjust the image to your liking.  For example, if you are using a mirror ball, you can use the clone tool to remove the photographer from the shot.

You can also save the image and use it in other applications like After Effects, or as a light probe image in a 3D application like NewTeks LightWave 3D.

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Stephen Schleicher is a well known writer, visual effects artist and media guru! You can see more of Stephen at
www.majorspoilers.com and www.stephenschleicher.com
Related Keywords:hdr, hdri, high dynamic range imaging, photoshop, adobe, cs2, camera raw, after effects, 32-bit, lightwave, 3d, light probe, mirror ball

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