Color shift when flattening layers. Huh?

First time this has happened to me.

I have a monochrome layer created in Nik Silver Efex which is set to "Luminosity" (Image 1)

When I flatten the image, the color is shifted, most noticeably in the magenta dress, but also in the golden soil and somewhat in the green dots, the faces, and the sky.

I always assumed that flattening gives you exactly what you see, just all in one layer. I have never seen such a change in the look brought about by flattening?

Any thoughts on how to maintain the color when flattening the layers?

For what it's worth the EXIF data says that the colorspace for the original image is sRBG

Rad

Can you zoom in to 100%, then see if the colour shift occurs when flattening?

Well, well well.

THAT was unexpected.

At 100% it shows no change between the flattened and unflattened images, and the result is much more like the flattened image rather than the layered one.

I can only assume that it has something to do with the rendering engine in Photoshop. When an image in not at native resolution, then it has to interpolate, and perhaps the interpolator's handling of color information is different than it's handling of luminosity? Maybe?

At 100% I am toggling back and forth between the flattening step and one step before. The image at 100% does not change, BUT, the thumbnail in the Navigator palate bounces back and forth between more and less saturated.

Weird.

Thanks for (surprising) suggestion.

Rad

Ok. So, start with the image filling your screen (the layered image, not the flattened one) then use Ctrl + to zoom in step by step. Tell me at which step the colour changes.

67% is the same as 100%

50% appears more highly saturated than 67% or 100%

33% appears slightly less saturated that 50%, but slightly more saturated than 67% or 100%

25% presents the most highly saturated appearance, which is the same as the 16.7% that I put in my screen-caps.

That level of saturated appearance remains constant with further minifying.

Rad

In Edit>Preferences>Performance, how many Cache Levels do you have set?

Assuming that these may be interrelated, here is all the info.

Cache levels are fine. I'd be fascinated to know if there was a change to the situation if you turned off "Enable OpenGL Drawing" (and restarted PS).

The color issue remains the same. Admittedly, the only thing I did was zoom in and out, but the most obvious difference is that with zooming it instantly clicks from one magnification to the next. Previously is would "slide" from one magnification to the next.

Oh well.

Rad

Excellent. So in that case, this is simply a problem with visual interpolation of the greater-than-usual noise/grain detail in the Efex edit. Not an actual problem with your system.