Pixelmath equation help please

[stevek]

Hi,
If I have two images, say A and B.  What Pixelmath expression would equivalently say "If any given pixel in A is of over 0.85 in K value greyscale then replace it with the same Pixel from image B" ?
How would I do that please?

[pfile]

iif(image_a>0.85,image_b,image_a)

the syntax here is (condition), true-case, false-case

pixelmath always operates on the same pixels from the input images unless you take pains to cause it to do otherwise.

rob

[stevek]

Wow, thanks Rob!
I was expecting the equation to be very much more complex than that.