Demonstration of X-Trans Under-the-hood RAW Spatial (Noise) Filtering

tradesmith45 wrote:

jm10 wrote:

Couple of things. First, do you think that this type of filtering has an effect on general photography (other than astrophotography) and secondly, could Fujifilm implement some sort of a "switch" if they wanted to?

Good questions. On the second one, don't know but they probably can implement a selection in firmware - if there's processor memory capacity available for the code. Sony changed their star-eater filter in a firmware update.

Regarding general photography, the answer broadly is the filtering will impact all RAW images w/ exposures over 5 sec. The filtering seems to impact all ISOs.

Specifically how it may effect general photography is harder to be exact about. One of the astro folks who worked on this & who has lots of experience w/ multiple camera brand filtering stated that unlike other sensors, he is unable to predict how images will be effected by Fuji's filtering based on his analysis. That is one of the big reasons I did the real astro image comparisons. Lets see what we might guess based on one of the image comparisons I posted:

The filtering is different in the 2 X-trans cameras but has the strongest impact on darker pixels in both. But even the brightest stars have been affected by smoothing in both. Whether the false color pixels in the X-T2 is the result of filtering or black points in each channel or something else is unknown.

So for general photography beyond 5 sec, we could expect filtering to slightly reduce shadow detail & for some X-trans give a color tint in deep shadows. But there could be some small reduction of all detail as would occur from increased NR adjustments in RAW conversion.

Careful testing by someone could look for this & confirm/disprove these expectations. A scene w/ a wide range of brightness w/ deep shadows, plenty of small detail, a sharp lens & several cameras would be needed.

Most RAW images will have NR applied during post. It may be that a useful strategy for dealing w/ the filtering would be to apply less NR in post for images over 5 sec. And sharpening methods & settings may need to be different if the filtering creates artifacts. I saw some evidence of artifacts but haven't tried to investigate that specifically.

Hope this helps.

Thanks for your detailed response tradesmith. Lots of food for thought here...I was not aware of the false color pixels in X-T2 - looks quite obvious in your comparison. I would venture a guess that for most Fujifilm users your study may appear purely academic. I find it quite useful - we need to know the limitations and perhaps peculiarities of the tools we are using. It the very minimum there may be situations where a known camera weakness could be avoided.

In this case a single shot >5 sec in a deep shadow scene could be replaced with a combined couple of shots with a 2 or 3 sec exposure. This is of course if you are really concerned about the results:-)

Please keep us posted if you uncover more useful info.