Not a RawTherapee issue, just curious

I have been using RawTherapee on Linux for several years. Thanks to all who contribute.

I was on vacation in Europe this summer, my last stop was Kinderjidk Netherlands where they have all the wind mills. I took a bunch of pictures, lovely place, then got home and processed them. I noticed something very odd, to me at least. Some, probably most, wind mills came out brown, but in some pictures the same wind mill came out gray. See the attached photos. I promise I am not playing a trick. :slight_smile: In the two photos I show I used the same “Daylight” white balance to see if that mattered. I do know at some point in my picture taking I used a circular polarizer, not sure which pictures have it and which don’t. I have other photos not included here that do the same thing, usually the same wind mill comes out brown but sometimes its gray. I am curious as to why. Any ideas?

Is one windmill under the shadow of a cloud in one frame, but not in the next frame?


Yes, it’s a cloud shadow, the grasses are also in the shade. You can also see that the shadow on the darker Mill is a bit more diffuse and less deep than the other one.

In the first photo the windmills that are not in the shadow are brown. Only the one in the foreground is bluish grey. I think that when in shadow, the building material is reflecting the blue sky.

Cloud shadow seems likely. If you look carefully, the grass around the gray windmill and lily pads(?) in the foreground are also darker but he the other foliage retains the same shade.

I can understand that the lightness or darkness would change depending on the cloud cover, but I am not seeing how the color changes? The green grass is either lighter or darker, but its still green. Maybe something in the materials used in the building “polarizes” (for lack of a better term) the light differently depending on direct light (no clouds) versus diffuse light (clouds)???

In general, parts in the shade in an image have a different color temperature, that’s why every digital camera with white balance presets have different presets for sun and shade.
If you look at the second image, there’s a blade shadow at the top of the mill which has the same blueish tint as in the first image.


Objects in the shade are lit by the light coming from the blue sky.
The graph here shows the different spectrum between the blue sky and direct sunlight

Additionally, objects in the shade are lit by light reflecting off nearby objects. This can be a real pain for wedding photographers who get a green tint in the shadows from the light reflecting from the grass on a white wedding dress.

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