Sunday, July 5, 2009

Controlling dynamic range with layering. Also HDR, Stitching,

(The photo above is combination of two frames shot at radically different exposures, and then combined into one photo. The brighter frame was exposed at a 20th of a second, and the darker frame was exposed at a 200th of a second to show color and detail of the sky. That's a little over 3 stops difference between the two.)

Decided to finally try getting into using "layers" in Photoshop. I've only ever used it before to apply text to a photo. It turns out that in order to do that, Photoshop creates a transparent layer over the top of the image that you're working on, then you can type your text onto that layer. When you are done, you can "flatten" the image and save it as a JPEG or PNG or many other formats. You can also flatten an image at any point during editing and just keep adding layers, theoretically there isn't a limit to this technique. PNG is generally preferred for text, seems to give cleaner edges and it doesn't do the photo any harm either.

This time however, I wanted to merge the dramatic sky with the daylit foreground. The sky was much brighter than the foreground, so I took two exposures: one I metered for the foreground, and the sky was blown out and featureless. I held the camera as still as I could and then metered for the background (the sky). In that one the foreground was very dark, almost silhouette. I knew at the time that without using my tripod there'd be a good possibility of moving the camera just slightly, making it much more difficult to align the layers later on. For me, when I try something new I'm much more comfortable doing it kind of quick and dirty just to get the concept. So that's how I approached this. I also knew as I was shooting that the highly detailed tree against the sky would be a real problem. It was. And I did slightly move the camera which was a bigger problem. I settled for "strange" across the board in this photo, not worrying about getting it perfect. It's bizarre, and maybe even unproductive but when I set out to experiment I sometimes make sure that the final product would have been "born to lose." It's like giving yourself permission to really play around.

In the past I have had no interest in doing composites ( elements from two or more photos combined into one ) but I'm starting to loosen up. Even Ansel Adams did this, not in Photoshop but in the darkroom, manually combining two or more negatives onto the same print: not to do something silly like putting a dog's head on a pony, but to allow greater control over things like contrast, texture and sharpening of an image.

As to my "Old Technicolor" color scheme, well it could just be a phase that I'm going through. "Old Technicolor" combined three sets of film shot through filters, red, green and blue which were then laminated later. The result was a super dense negative with extremely rich and rather unrealistic color. I loved it. If you ever get a chance to see "Robin Hood" with Errol Flynn in a movie theatre, or "The Wizard of OZ" on film then you'll see what I mean. I was lucky enough to see Robin Hood on film for a Film Appreciation class and it left an indelible impression. I don't think it's the same on TV, not even in HD but it's still worth seeing.

My photo above reminds me of an HDR photo ( high dynamic range ) and that is sort of what it is, but not quite. HDR photos typically combine a whole bunch of frames of the same scene, always taken with a locked tripod and they span a much broader range of exposures in smaller increments, all the way from nearly black to almost entirely blown-out and over-exposed. The over-exposed shots are used to reveal detail only in the darkest shadows. The under exposed are to reveal color, tone and details in the very brightest areas. The end result looks dreamy and unreal in most cases. In a lot of cases it looks terrible, but some are trippy and pretty cool to look at.

If I were to make a prediction; pretty soon digital cameras will come with the ability to do HDR right in the camera with the touch of one button. Maybe not right away though. I haven't searched for an easy software solution lately, but I will some time because I think it will be a fun thing to have the ability to do. I admit that I'm hoping my next camera will come with HDR built in. Cameras today have a much shallower dynamic range than the human eye, but with HDR there is the capability of going way beyond what the human eye can see. The downside of course, is ugly, flat looking photos with no depth, no true sense of shape and form, unrealistic colors. . . they can look quite cartoonish. Light and shadow can be a delicate thing to mess with.

There are already some cameras which will stitch images in camera, but last time I checked the stitched images were not at full resolution which pretty much defeats the whole purpose of stitching. Stitching is not the same as layering. In layering images are laid over each other and combined through various means like removing areas of the top image to reveal the lower image. This can be done with varying degrees of opacity/transparency for some really great looking effects. Stitching is combining images edge to edge to create a larger picture. It's often used to shoot panoramic scenes. I haven't done that yet either but it looks way easier than utilizing layers well. There already is software which makes stitching pretty much a one button operation.

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