PL4, Color Efex histograms don't match?

I am very confused about the way that PL4 and Color Efex Pro render luminance values.

Before exporting a TIFF image to Color Efex Pro, I always ensure that there are no clipped highlights or shadows.

When working in Color Efex Pro, even though I am very careful to ensure that there are there are no blown highlights or shadows in my TIFF images, I find that when I save the image and return to PL4 there are blown highlight and/or shadows, sometimes huge amounts.

In Color Efex Pro, I always have the “Show Clipped Highlights”/“Show Clipped Shadows” checked, so the blown values are easy to spot in CEP. When I am looking at the processed TIFFs in PL4, I always make sure that I am looking at the “No Correction” preset. So, it seems to me that PL4 should be giving me the very same image I just finished processing in CEP.

What am I missing?

Hi @MojoGene,
when you want to work on your file (in PL, Nik …) avoid adjusting black and white point just shy of clipping, but give it some leeway instead of.

my preferences >> For RGB images …
Screen Shot 02-28-21 at 09.59 PM

have fun, Wolfgang

Wolfgang: Thanks for jumping in. I have taken your suggestion on the Correction Settings and I have been avoiding any values close to the extremes 255/0.

Seems to be odd, however, that, e.g., a 252 value in CFP would render as 255 in PL4.

I submitted a test case demonstrating a similar problem using HDR Efex Pro. The file exported was a lot darker than what I had been working with in H.E.P. So far, I haven’t had such an issue with C.E.P. - but now I think I probably just didn’t notice it.

Thanks, Greg. I remain frustrated by this. I export an image with no blown highlights to CEP4, make adjustments with meticulous attention to avoiding clipping, and then view the resulting mage in PL4 only to see wholesale clipping on both ends.

Be aware, though, that PhotoLab will show clipping at values close to 0 or 255 where there really isn’t any clipping. A way to demonstrate this is to activate FilmPack 5 within PhotoLab and select a black and white frame. The clipping indicators will engulf the frame.