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Blending Images in Median mode...

PostPosted: Sat Nov 14, 2015 10:12 pm
by den
The following was posted on the Digital Light & Color message board for Picture Window Pro software which I frequent by another member:
Here is an article about stacking several images to eliminate the moving elements in the picture

What interests me is the simple technique: taking the median of each pixel across all aligned images, to do it.

Would this be useful for improving de-ghosting for image exposure sets in SNS-HDR?

...and for a 3 exposure image set [-1.5ev, 0ev, and +1.5ev] would it be necessary to have multiple images at each exposure for the median filter blending to be effective?

Just curious...


Re: Blending Images in Median mode...

PostPosted: Fri Nov 20, 2015 12:46 am
by Sebastian Nibisz
Thanks Den.

This works well when all the images are just as bright. Can set the same brightness for different exposures, but then the missing of details in the highlights or shadows, and it does not work well. I will analyze this yet.

Re: Blending Images in Median mode...

PostPosted: Mon Nov 23, 2015 2:38 pm
by markdfink
This would be effective if your scene has lots of moving content, but as the original article mentions, all exposures must be the same. So, you could shoot multiple exposures at +2, 0 and -2, run this process on each of the three exposures to create three images ready for HDR that don't have any movement in them.

However, things like moving leaves and branches might not turn out quite the way you want. It seems to me this would work best when the scene itself doesn't move, only elements moving through the scene. It still doesn't address our issue of movement between exposures for HDR. That is something that would be really beneficial.