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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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Tue, 11 Mar 2014 19:45:40 -0400
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Re: [SCIART] Getting white backgrounds white. Sigh.


Geoff,

You can do the same thing in Photoshop by using the white dropper on a curves adjustment layer.  Clicking that dropper on any value sets that value to 255.  Karen Ackoff mentioned this earlier in this thread.

Some use white and black and midtone droppers to set the general range and contrast slope in photos.  I've always felt that trying to estimate the "midtone" gray is haphazard at best.  Too, looking at the histogram in a curves layer, one can easily find the black and white limits of the image just by sliding either end of the curves line up to that particular limit.  A move that may or may not be advantageous to the appearance of the image in question.  I have, however, occasionally used the black and white droppers when converting RGB images to B/W.  For the most part I like to keep as many options open when processing any image, photo or artwork, because they're all different to begin with.

b


On Tue, Mar 11, 2014 at 6:15 PM, Geoff Thompson <[log in to unmask]> wrote:
In Lightroom you can also click on a background paper to make it white. I
had to do this when photographing watercolours for a kids' book illustration
that had been done on very yellow paper. The designer wanted pure colours.
So I was able to deliver rich depth of colour with a pure white background.
http://www.shop.qm.qld.gov.au/default/happy-birthday-muttaburrasaurus.html
http://www.shop.qm.qld.gov.au/default/where-s-your-teddy-muttaburrasaurus.ht
ml

Cheers,
Geoff

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--
Bruce Bartrug
Nobleboro, Maine, USA
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www.brucebartrug.com

The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.  - Albert Einstein

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