Ответ Дэна Маргулиса в оригинале.
[quot]Dear Natalia,
You are right that Lighten mode does not always work in LAB, but fortunately
we can avoid the problem provided we agree to make one extra step.
Since you are creating a mask, you need one separate channel only--we do not
need to change the entire image yet. Let us say you are making it from the B
channel and you wish to do a blur and fade to Lighten, but Photoshop does not
permit this.
Instead,
1) Layer: Duplicate Layer
2) Choose the B channel (top layer) and apply the Gaussian Blur as previously.
3) Image: Calculations. Choose for Source 1, Layer=Merged, Channel=B. Choose
for Source 2, Layer=Background, Channel=B. Choose for Blending, Lighten. Now
Photoshop makes as a separate channel the mask that you need.
If instead you just wish to apply the Lighten-Blur directly to the image,
then instead of Image: Calculations use Image: Apply Image. The B channel on the
top layer must be active.
Dan Margulis[/quot]