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A
Simple Colour Graduated Filter using Photoshop - by
Chris Maddock
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Following on from my Neutral Density Graduated filter
article, this uses the same technique to apply a graduated
colour filter.
Here
I have an image that I shot at Bedruthan Steps where
Murphy's Law prevailed and the sun disappeared behind
a cloud bank before giving me any colour in the sky.
I'm going to use this as the example and add a simulated
warmup grad filter.
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Now, I only want to warm up the sky (and a little
of the distant sea) but a grad filter will give
a horizontal transition across the whole image -
including the rocks, which I don't want.
So
the first thing I need to do is to select the area
which I want to exclude. The quick and dirty way
to do this is to use the Magic Wand. As it happened,
with a tolerance of 32 one click selected all I
wanted, so I don't need to alter the selection at
all.
Further
detailed adjustements to the selection can be made
but this is outside the scope of this article.
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I now save this selection for use later, by choosing
Select->Save Selection. I left the destination as
the current file and the Channel as New, just entered
something in the Name - I've used "rocks"
Finally,
I clear the selection, using Select->Deselect
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Now I duplicate the layer (Layer->Duplicate) and
leave it as the offered name, before adding a new
layer (Layer->New->Layer).
I
haven't renamed this layer but I have altered the
trancparency to 25%, the reason for which will become
clear later.
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A quick glance in the Layers Palette shows that I now
have three layers - the original "Background"
image, a duplicate "Background Copy" and the
new "Layer 1"
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I
now add some colour to Layer 1, to start creating
the simulated filter. First I click on the colour
picker foreground colour and type in the colours I
require. In this case I am simulating a Wratten 85
warmup filter so I use R 228, G 137, B 0.
Other
values for different filters are given at the end
of the article.
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Having
selected the colour, I now use the Floodfill tool to
apply it to the whole of Layer 1
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I now combine the layers Layer 1 and Background copy
so that the whole of Background Copy is warmed up. This
is done in the Layers Palette by clicking on the arrow
at the head of the tab to open the menu and choosing
"Merge Down".
This
merges just the selected layer and the layer below it
in the list, leaving us with two layers - the original
image "Background" and the warmed-up duplicate
"Background Copy".
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Now,
as with the ND Grad article, I add a Layer Mask to the
"Background Copy" layer.
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Now
I apply the gradient to the masked "Background
Copy" layer. I set the colour picker foreground
colour to White, select the Gradient Fill tool and draw
a vertical line on the area that I want the graduation
to cover.
Voila!
one gradient warm-up filter
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However, if you look closely at the previous image you'll
see that the gradient has also covered the rocks. Not
what I wanted.
Never
mind, I'd already planned for that - remember the selection
I created and saved?
I
now load that selection onto the Layer Mask that included
the gradient fill, by going to Select->Load Selection,
pulling down the Channel list and choosing the entry
"rocks".
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Once
the selection is loaded, I can use it to add that area
to the Layer Mask so that the grad fill doesn't cover
the rocks.
I
switch the Colour Picker foreground to Black (to add
to the mask), select the Floodfill tool and click inside
the selection.
Now
the rocks have been excluded from the grad fill.
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Having removed the selection (Select->Deselect) I
now want to adjust the amout of the warm-up as it's
a bit more than I wanted.
In
the Layers Palette I select the Background Layer by
clicking on its thumbnail - the image thumbnail, not
the mask - before adjusting tthe Opacity slider. 76%
is about right so I'll leave it there.
I'm
now happy with the result so I flatten the image (Layer->Flatten
Image) and it's ready for finishing off.
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The RGB values I used above were for a Wratten 85 and
are those used in Photoshop CS's Photo Filter tool.
Other filter values that CS offers are as follows and
can be used in the same way when setting the colour
of the filter in this technique;
#85: R=228 G=137 B=000
#81: R=235 G=177 B=019
#80: R=000 G=066 B=255
#82: R=000 G=158 B=255
All of the above have an indicated density (transparency)
of 25%.
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All
text and photos are copyright © Chris Maddock,
2007
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