Canon G1X3 grey fringing in Adobe Camera Raw and how to fix it 9 February 2018

This is the scene with localised color fringing correction applied as described in the text. I used the Grad Filter on the top right of the frame and the Adjustment Brush on the walkers in the sun on the right side. This has removed most of the fringing without adverse effects elsewhere in the frame.

The Canon G1XMk3  is a good camera within its capability envelope. Many people myself included had hoped that envelope would be larger, extending to a wider aperture lens, more advanced video and a faster processor among other things.

But it is what it is. Overall picture quality is about the same as that delivered by my little Sony RX100 Mk4. The G1X3 has better ergonomics and marginally more resolution of fine subject details but you have to look very closely at matched images enlarged to 100% on screen to pick this. The RX100Mk4 is better in low light because of the wider aperture lens.

I took my G1X3 out recently and stress tested it with some scenes having high brightness range. This revealed a problem. Actually two problems, one leading to the other.

The G1X3 is prone to color fringing in RAW files at the edges of subject elements where there is considerable brightness change across the boundary between the subject and the background.

This is typically seen on tree branches and foliage in bright sun but can occur on any type of high contrast edges.

Characteristically the camera produces purple/red fringing on one side of a subject element and green fringing on the opposite side.

Enlargement of the top right of the frame showing uncorrected purple/red and green fringing.

Over several thousand images I have found that the out of camera JPGs automatically correct for most of this fringing without adverse secondary effects.

However when converting RAW files with Adobe Camera Raw I encountered the second problem which is grey fringing on subject elements distant from the corrected color fringing.

Camera Raw has dual sliders for correcting color fringing. One controls the purple spectrum, the other controls the green spectrum. These sliders are effective in removing most of the fringing.

This is what the image looks like after global defringe corrections have been applied in Camera Raw. It might seem OK until you look closely when you will see grey fringing in many locations.

However when the fringing is prominent, as it can be in some situations, this correction produces the unpleasant phenomenon of grey fringing elsewhere in the picture.

This problem is not exclusive to the G1X3 or to Canon equipment but I have not seen it present in such obvious fashion on my Sony and Panasonic cameras in recent years.

Clearly Canon’s JPG engineers are well aware of this issue as they have pretty much eliminated it from the out of camera JPGs.

This is an enlargement of the center section of the full frame showing the grey fringing more clearly. You can see it easily on the legs and other parts of the of the lady running, the neck of the girl with the apricot T shirt and in many other locations.

After some experimenting with various options I have come up with a fix for the grey fringing issue which appears to work decently well in most images.

Step 1. In Lens Corrections>Profile, I check [Remove Chromatic Aberration].  This will usually reduce the color fringing significantly.

Step 2. I identify where the color fringing is present, it will usually be around the periphery of the frame, then select either or both the Adjustment Brush or Grad Filter in Camera Raw and apply a local defringe correction using the generic Defringe slider. This does not allow fine tuning by color like that seen under the Lens  Corrections>Manual tab but it works well enough to remove most of the obvious fringing.

The point is that the defringe function is not applied to the whole image thus avoiding the grey fringing problem.

The photos and their captions illustrate the issue.

The problem only occurs in certain situations and will likely not be encountered often or at all by some users.

I have no idea whether other RAW converters including Canon DPP  have this issue. I don't like DPP and never use it in my regular photographic work flow.