Saturday, August 14, 2010

High Dynamic Range Pictures

When someone takes a photograph, what they want is an image to remind them of what they were seeing at the time the photograph was taken. In most cases, the camera cannot begin to approximate what we see. Mama Bear struggles with pictures that involve water: the colors and hues that abound in these environs, and the ability to see beneath the water's surface, is difficult to replicate with a camera. Papa Bear also struggles - to show both the colors of the vegetation and that of the sky when the camera wants to key on one or the other and usually thereby renders the picture somehow not quite was was seen. The dilemma is not a new one: photographers for years have debated what-I-took vs. what-I-saw and how much, if any, post-processing of a photograph is appropriate and/or allowed. Ansel Adams, for example, used a number of techniques to render his images, among them dodging and burning.

As Papa Bear has been working with his camera this summer, he has been exploring post-processing mechanisms to render a photograph closer to what his eye saw when he took the picture. He does not want to paint the photos to arbitrary values, but to take multiple images of a single object and then to integrate the multiple images, pulling the blue of the sky and the green of the vegetation together in a single image that shows them both as his eye saw them (or such is my understanding of the process used). The technique for this type of rendering is called High Dynamic Range (HDR). The photos below show on of his attempts to use this technique and show both his input photographs and the resultant output photograph. The photos were taken on our Beech Mountain hike. Papa Bear uses comptuer programs to do the HDR blending - they selects what is seen as best values and uses them. In this instance, there were only two input pictures. Note that I have used a program to shrink the number of pixels in his pictures (as I always do for space reasons), and I kept them all the same size so that you could better compare them. Also note that not all pictures need this processing, and what you are seeing today, though similar to photos in previous blog posts, is new: this is the first time Papa Bear has shared an HDR picture with me.


























Input - Vegetation

Input - Sky



 

Result after HDR

 

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