我也是有遇到同样的问题, 有写信去问OM了, 得到以下这个建议.

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It seems to us that the difference might be due to the processing engine.

We did not recognize this E-1's phenomenon with E-410 at RAW.

It might be due to the difference of the compression rate of RAW files
of each camera.

In order to improve this problem, please try the following setting
when you develop RAW to JPEG with OLYMPUS Studio 2:

- Noise Filter "ON" on basic2 tab.
- Adjust on "False Color Suppression" and "Isolated Point Removal
on advanced settings tab.

It is recommendable to save images in high quality.

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p/s: 这个情况好像在410的RAW上没有那么明显.