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Gradient maps

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  #1  
Old 07-18-2010, 07:27 PM
atholg atholg is offline
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Gradient maps

I have been restoring images for OPR for some time. My efforts at replacing damaged color leave something to be desired, particularly when the area is high contrast and there have to be subtle hue and saturation variations to achieve a natural result.

A search located http://www.retouchpro.com/forums/sea...earchid=912971 and I have so far found the method Ed describes to be useful. I have progressed to using gradient maps using 3 or 4 different hues. However, unlike a normal gradient the opacity stops in a gradient map show up in the tool but not on the image. A normal gradient is modified by the stops but is not appropriate in this case.

At this stage I am using the sponge tool to de-saturate the flattened image where necessary. Has anyone had any experience with gradient maps and had success with opacity stops?

I am using CS3 with Windows

Thanks
Athol
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Old 07-18-2010, 08:30 PM
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mistermonday mistermonday is offline
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Re: Gradient maps

Athlog, welcome to RetouchPro. You need to have data in the image whose luminosity is approx the same as the luminosity at which you set the stop. So for example, if you set the 0 stop to be green, the black stop to be red, and the mid point (~128) to be blue and you apply that Gradient Map to an image which is all gray or midtone with no highlights or shadows, the entire image will be blue with no red or green. So a Gradient Map may not provide the best results for that image unless you redistribute the tones of it with curves or other adjustments.
Regards, Murray
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Old 07-18-2010, 10:53 PM
atholg atholg is offline
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Re: Gradient maps

Hi Murray,
Thanks for the reply.
I have been working on an OPR image but have attached a grey scale which I have applied two green to red gradient maps. I have included the editor display for each, as you can see they are very different but the applied maps are identical.
The reduction in saturation towards maximum and minimum brightness is a function of the Ed's saturation mask applied to a luminosity mask as per his documentation.
I have done a bit of searching on the web, there are some mentions of issues with the gradient editor display using normal gradients in CS3 but I haven't been able to find anything useful about gradient masks.
Cheers

Athol
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Old 07-19-2010, 11:56 AM
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mistermonday mistermonday is offline
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Re: Gradient maps

Athol, there are thousands of tuitorials available on the Gradient Map - just goole Gradient Map Tutorial. Many are in video format as well if you prefer to learn that way.
Gradient Masks usually refer to a black to white (or reverse) or Black / White to transparency gradient that are applied to a layer mask. These gradient masks effectively allow whatever effect has been done to a layer to be applied in a graduated way across the image. For example if you have a landscape scene where the sky is too bright and the foreground is normally exposed, you can apply a curve adj layer which darkens the entire image. You then apply a black to white gradient on the layer mask so that the darkening effect is strongest in the sky and very gradially has less and less an effect the lower down it gets in the image.
Regards, Murray
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