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Author Topic: Changing the colour of one object in an image?  (Read 1932 times)

Dinarius

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Changing the colour of one object in an image?
« on: January 07, 2008, 10:36:45 am »

I have a night shot of the facade of a building in which all the windows are the same except for one and I need to change it.

Basically, it's a shot of the facade of a hotel and the light through all the curtains is the same colour except for one room. All the other rooms are lit by tungsten (if at all) while this room appears to be lit by fluorescent or some such.

I've tried selecting other windows (using the Polygonal Lasso Tool) and then Copy/Pasting into the window I want to change. This is OK, but not great.

Ideally, I'd simply like some way of selecting the bad window and changing the colour of the curtains so that they match one of the windows I'm happy with.

How can I do this? Or is there another way?

Thanks.

D.
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Jonathan Wienke

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Changing the colour of one object in an image?
« Reply #1 on: January 07, 2008, 10:44:06 am »

Do a separate RAW conversion of the image with an alternate WB setting to correct that window. Then paste that conversion over the main image and blend together with layer mask.
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01af

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Changing the colour of one object in an image?
« Reply #2 on: January 07, 2008, 12:21:53 pm »

Jonathan's method will work fine ... but it might be tricky to get the colour adjustment exactly right. The colour sampler tool will help, but still it might be tedious to get right.

So here's another method which may or may not work better than Jonathan's ... just give it a try.

Carefully select the offending window using your preferred method---e. g. lasso, polygonal lasso, or magic wand. Selecting a window from a building's facade should be a fairly easy job (unlike selecting a person's head with fly-away hair, for instance). Put the selected part of the image onto a separate layer through hitting Ctrl-J (Cmd-J on the Mac). Do not select much of the surrounding wall; only select the part that you actually want to have the colour adjusted.

Go back to the background layer and do the same with another window; select it in the same way you did with the first window. Now you're supposed to have the background layer, one layer with the offending window, and one layer with one of the well-coloured windows.

Now click on the layer with the offending window to make it the active layer, then select Image > Adjustments > Match Color. In the lower part of the dialog, select the layer with the single fine window as the source, hit OK, and you're done.

-- Olaf
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Dinarius

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Changing the colour of one object in an image?
« Reply #3 on: January 09, 2008, 05:02:58 am »

Guys,

Thanks for the suggestions.

Olaf's solution worked a treat! The window looks identical to the others now.

Isn't digital marvellous? A few years back, with the same problem, I would be hoping that the art director/graphic designer made the changes after scanning the film. Some chance! Digital allows you to deliver the file exactly the way you want it. I love that.

Thanks again.

D.
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