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HDTR - high dynamic time range - tutorial set (4/4) | by Martin Krzywinski
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HDTR - high dynamic time range - tutorial set (4/4)

This is a HDTR image showing 7:20am to 5pm on 9 December 2005. It is a techically better executed composite to my first HDTR post.

 

171 images were used to create this composite. Most images were taken at 5 minute intervals, except those at the end of the capture period, when the interval was reduced to 1-2 minutes.

 

Compositing method: non-uniform sampling (left to right) using a logistic function, temporal blending using (1,2,4,2,1), spatial blending using w=0.5 and a=1.

 

The abrupt change in image brightness just past the half-way mark reflects the change in the web cam's exposure settings, which changed from 1/100s f/3.2 -1/3EV compensation to 1/160s f/4 -2/3EV compensation. Such a drastic change of about 1 1/3 f-stops should be avoided when making HDTR images! But I really should not be complaining since I don't operate a web cam and am lucky to get these images from www.katkam.ca.

 

This photo is associated with a Technique group tutorial.

 

Do you have HDTR images? Consider posting them to the HDTR Flickr group.

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Taken on February 14, 2006