[cocasana]

Hi there,
I was wondering if the color definition I loose converting from Pro Photo Rgb to Lab mode to apply Lightness channel sharpening is worth while on your opinion. At that point isn't it useless to convert back to ProPhoto Rgb? Why not printing directly in Lab mode?
Thank you very much,
Carlo

[Duv]

Originally Posted by cocasana

Hi there,
I was wondering if the color definition I loose converting from Pro Photo Rgb to Lab mode to apply Lightness channel sharpening is worth while on your opinion. At that point isn't it useless to convert back to ProPhoto Rgb? Why not printing directly in Lab mode?
Thank you very much,
Carlo

Hi Carlo.

Welcome aboard!!
I don't believe you loose color definition converting any profile to LAB. LAB sharpening is one of my most frequently used methods. I don't believe you can print in LAB mode so you have to convert back to RGB or CMYK for prepress.

Cheers

Dave

[goose443]

If there's any loss it'll be from LAB to RGB though that should be small. The reason is that RGB's color gamut is smaller than LAB which really has none. The big loss will be converting to CMYK which, depending on the profile used will have a very restricted gamut. Still, if the photo warrants it, it is well worth the effort of correcting in LAB, especially L channel since you avoid color shifts.

[chromaticstyle]

you can lose color information converting from RGB to LAB and back, but it probably won't be much. but, there is a better technique for sharpening just the luminance of a photo, that will cost no loss at all!

once your ready to sharpen, make sure everything is flattened. run unsharp mask just like normal. with the following technique, i will actually oversharpen a bit more than normal. like .2-.3 more on the radius, and 50%-100% more on the amount.

after your run unsharp mask, go to edit > fade (unsharp mask).

change the blend mode to 'Luminosity' and fade it back a little bit, usually to 70%-80%.

spladink! just like that. same as sharpening in LAB. hope this helps. good luck!

[Duv]

LAB vs RGB Luminosity. Something to consider. (Compliments of Dan Margulis: Photoshop LAB Color) To me the color looks better in LAB plus you don't see the white fringing. While I do most of my sharpening in LAB, most oftern I don't see a difference but when I do it almost always favors LAB.

Cheers

Dave

[cocasana]

for your very interesting and usefull replys!
Carlo