Using Enfuse for Multi-Exposure Noise Reduction

This is a discussion on Using Enfuse for Multi-Exposure Noise Reduction within the Post-Processing forums, part of the Photography Tips category; Noise reduction always bothered me on principle. While in college, I was always taught to always avoid removing data, once it is gone from an ...


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  1. #1
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    Noise reduction always bothered me on principle. While in college, I was always taught to always avoid removing data, once it is gone from an image it cannot be recovered. Most noise reduction methods aim at removing noise, unfortunately, noise is what makes up an image, it's only how noticeable and whether the amount of noise is greater or less than the resolution of the image. Most noise reduction techniques are clever ways to soften noisy gradients while keeping sharp detail un-blurred.

    Unfortunately, these techniques are usually at the expense of resolution to some extent, and the greater the noise in the image, the more resolution must be lost in order to achieve a noiseless image.

    There are some methods which preserve detail very well. Unfortunately, these methods are often times costly - and in the end you're still removing data from the image even though this data might not have a significant effect on overall image quality. The best of these methods utilize specific noise profiles for the camera.

    Another method is to use multiple exposures (an image stack) to average noise while keeping detail. This method compiles data into one image, rather than removing data from the image. The result, if done right, is an image just as sharp as the data set it was given.

    The technology I used to sample this technique is a GPL program called Enfuse. It was originally designed to create a "best exposure" by combining multiple exposures into one 16-bit image (this differs technically from HDRI) but has since been used to remove moving objects, noise, create HDR images and probably a million other things too.

    While testing, the technique works best with very large stacks, producing nearly noiseless results using 26 images (nearly, is key here). But in reality, you don't likely need to use this many images since noise is often less noticeable in finished products. There is some very minute blurring though this I think is due to camera shake.

    In the included sample, the low IQ is due to the camera I chose, an inexpensive Samsung Point and Shoot taken at ISO 800 to maximize noise.

    Of course, this method cannot be used with moving subjects, and often this is when you want higher ISO's in order to get faster shutter speeds. So it's practical application may be somewhat limited. Nevertheless, the technique is very effective.

    At the bottom you will find links to various GUI options. I used Image Fuser for OS X, and used the basic settings.
    Attached Images Attached Images     
    bear with me. i don't have an escape button...


  • #2
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    Thanks for the demo.

    I have read, but have not tested, that similar results are possible using Photomatix' "exposure fusing" option, using the averaging method.


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  • #3
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    Quote Originally Posted by Grandpa View Post
    Thanks for the demo.

    I have read, but have not tested, that similar results are possible using Photomatix' "exposure fusing" option, using the averaging method.

    I am guessing that this is similar to (or maybe even is a proprietary GUI to) enfuse with more advanced processing settings. One nice thing about Image Fuser is that the finished HDR results look like what you'd expect from exposure fusion, though I need to do more testing to see if this is a good for HDRI.
    bear with me. i don't have an escape button...


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