Photomatix Makes HDR and Blending Easy
Photomatix is a stand-along program that creates an
HDR (High Dynamic Range) version of multiple exposures of the same
im
age.
It also automates conventional blending of multiple versions of the same
image, something we have heretofore handled by stacking them and
using a layer mask to blend in variations exposures to create a smooth
image.
Photomatix also has a tool called Tone Mapping that allows you to allocate the tones created from an HDR. This is also available as a plug-in for Adobe Photoshop CS2. It won't work with previous versions because only CS2 creates an HDR.
Why would we even want to do this? Consider the image of the John Day Fossil Beds to the right. A storm was moving in and the clouds roiling over the sunlit beds made for a dramatic photo opportunity. Unfortunately, the limited dynamic range of the camera's sensor gave me three choices. I could shoot for the sky and leave the fossil beds in shadows, properly expose for the earth and blow out the detail in the sky, or struggle for something in between and have both deep shadows and moderately blown-out highlights.
Another solution was to do all three—shoot multiple exposures of the same image and use the best of each. The image you see resulted from five shots, each one stop apart, taken by varying the shutter speed. Thus is important, because varying the f/stop causes a slight shift in image size and the varying exposures won't match.
The usual way of combining these images was to put each on a layer and mask portions to blend the exposures into one final image. This can be laborious, though there is a technique described in this tutorial on Michael Reichmann's Luminous Landscape that eases the process considerably.
Instead, I made an HDR—a high dynamic range version of the image. Photomatix (or PS CS2) combines all five images into one 32 bit image that contains the full dynamic range.
But
there's a problem. As this screenshot shows, the unadjusted HDR image has
such a range between light and dark that the monitor can't display it.
As it is, it's useless. It needs to be squeezed into a
16-bit per channel space or even into 8-bits per channel.
Photoshop CS2 has rather minimal tools to help you through this conversion. As one reviewer put it rather kindly, "It's a Version 1.0 tool." There are four conversion options—Exposure and Gamma, Highlight Compression, Equalize Histogram, and Local Adaptation. Some of these options have no user controls. Those that do are not particularly helpful. I tend to use Local Adaptation, since it gives me the greatest control.
Photomatix uses a special approach that is intuitive, fast, and gives you instant feedback. If you use Photoshop CS2, you are left with a 16-bit image in which the distribution of tonal values still isn't quite right. You must tweak it using a curves adjustment.
This is where Photomatix shines. Its Tone Mapping tool distributes the range of tones automatically with interactive help from you, while converting the image to either 16-bits per channel or even to 8-bits. The results are astonishing and far better than anything available in Photoshop.
Tone Mapping is available as a Photoshop
CS2 plug-in, allowing you to use it with that program's HDR tool.
However, I recommend springing for the entire stand-alone program,
Photomatix Pro. If you don't own CS2, this is a no-brainer. Photomatix
Pro makes the benefit of HDR
available to users of every version of Photoshop, to those using
Photoshop Elements, and to non-Adobe imaging products.
Even for those of us who do use CS2, however, the full Photomatix package offers great advantages. For one thing, the HDR creation and 16-bit conversion tools are more straightforward. I still haven't been able to get the results using Photoshop CS2's HDR in combination with the Photomatix Tone Mapping plug-in that I have with Photomatix Pro.
In addition, Photomatix Pro offers a bonus that is worth the added price and the slight inconvenience of working outside Photoshop. It has a straightforward digital blending tool that is superior to the technique referenced above or to any of the commercial actions floating around the marketplace.
The image of the Oneonta Gorge to the right was blended from two exposures. So far, a straightforward case for blending. However, I was using a lightweight tripod while perched precariously atop a rock. As a result, the two exposures were not in perfect registration. I have used Photoshop's Move tool to try to align them, but the results have never been satisfactory. The alignment option in Photomatix made quick work of the task. The results probably aren't worth it. The gorge has so much sunlight streaming in from above that it was a better candidate for HDR than the John Day Fossil beds. But the blending tool offers so much flexibility that I predict you'll seldom revert to layers and masking.
There are three blending options, 2 Images, Auto, and Adjust, with the latter offering the greatest flexibility. The blending process seems to be more than just the layer masking techniques available in Photoshop. The alignment option alone makes this a very special tool.
Photomatix Pro is available from HDRSoft. You can download the program and test it before purchase, although the finished image will leave a watermark. This handy tool is highly recommended. For a 15% discount, enter the coupon code "atncentral" (without the quotes) at checkout.
—Jim Lewis, Action Central