I'm sure you're right, Geoff, but I know very few photographers that venture into Lab these days.  Using curves layers in luminosity mode may alter the color balance but the effect is imperceptible in most cases.  At least to my eye.  I use LR but frankly find it a miasma of complication that I don't have in Photoshop.  LR is supposed to be the be all for photographers, but I often just use it just to convert raw images, then go to Pshop which is easier to use.  Of course, I haven't spent that much time trying to understand LR other than the download and catalog functions, so the fault there is mine.  If I had done so I could probably use LR to apply watermarks much more easily than doing batches in Pshop :).

Thanks,
Bruce


On Tue, Mar 11, 2014 at 11:00 PM, Geoff Thompson <[log in to unmask]> wrote:
Hi Bruce,
            I think the difference in Lightroom is that it resets the colour balance, although it can't generally do that on pure white. It needs a neutral grey. There is some way of doing that (i.e. reset the colour balance with an eyedropper) in Photoshop but it's complicated.
Photoshop always changes the colour balance when you alter contrast whether you use curves or not. It's a myth that curves solve all these problems in PS. You can set up an action to copy the background layer twice, fill the middle layer with 50% grey in "color" mode, fill the top layer with 50% grey in 'luminosity" mode, then set the blending mode of that top layer to "Color". You then have the tone layer separated from the colour layer and can adjust tone without major changes to colour. I know there are now LAB(?) settings that might make this possible without doing this but I'm not sure they really do.
Cheers,
Geoff

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