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Author Topic: raw processing & color fringes  (Read 4326 times)
CHoffman
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« on: March 25, 2019, 03:28:45 PM »

I notice my jpegs direct from camera (Nikon D200) have very little color fringing. Shooting raw, from another raw converter the problem is worse. From Qimage it's much better. Just to help my understanding, is this something there are settings for, or is the raw converter just smart enough to take care of it. I'm also assuming this is related to the Bayer filter, as the fringes are visible in the center of the frame, obviously at high magnification.
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Terry-M
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« Reply #1 on: March 25, 2019, 05:09:59 PM »

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From Qimage it's much better
Some time ago, QU raw processing was improved to reduce colour fringing. I remember noticing a significant improvement at the time.
There is no specific setting in Raw preferences although there is a tick box for "Special NR Maze Banding Chroma". That is ticked by default.
The lens quality is also significant with regard to colour fringing.
Terry
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admin
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« Reply #2 on: March 25, 2019, 10:41:13 PM »

As Terry indicated, Qimage has built-in fringing reduction.  It focuses on eliminating color fringing that can be caused by the bayer color filter array.  It stops there, however, and doesn't try to eliminate color fringing that is a result of lens chromatic aberrations so you can still see some color fringing if it is caused by the lens.  JPEG's from the camera are typically "over processed" to reduce color fringing more so JPEG's will likely show the least fringing, but it comes at a cost.  If you try to remove all color fringing, it will by definition remove some actual color detail in some areas.  For example, a thin yellow stripe on a leaf in the distance may end up showing gray if you de-fringe too much and you'll never know it was a yellow stripe.

So Qimage's raw refine is built to show you the image developed from the raw data as close as possible to how it was seen through the lens, so it is not adjustable there.  Further defringing can be done in the image editor if needed.

Regards,
Mike
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CHoffman
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« Reply #3 on: March 25, 2019, 11:34:53 PM »

Thanks! That helps a lot. I'm well aware of lens aberrations, but I'm looking at higher contrast targets in the center of the frame, so I'd expect the lens to be pretty good there. As I mentioned in another post, I'm just starting to do more with raw, and am trying to fine tune the workflow and understand what I see using different tools. Guess what tool wins again!
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