On 02/17/2011 11:24 PM, Suntot wrote
>> On 02/17/2011 03:00 AM, Suntot wrote:
>>> Well, I am new at this. Not even sure if what I am attempting is possible. 
>>> I am trying to change a specific color in an image. If I use 'color 
>>> selection' the edges don't change color. So I am trying to use color to 
>>> alpha... But, when I select by color, it seems to select all similar color 
>>> in the area, thus when I add a new layer it does the change the color I 
>>> wanted to change, but it also changes the rest of the image with a similar 
>>> color tone. What can I do to precisely select a specific color or portion 
>>> of an image with color to alpha?
>> Color-to-alpha only applies to the selection, so you can restrict its
>> effects by doing a selection first. For instance to remove a background,
>> use the wand to get a rough selection of the background, grow the
>> selection by  a couple of pixels so that it includes the edges of the
>> foreground, and perform color-to-alpha.
> I tried doing a selection but since both colors are similar it selects all. 
> Changed selection thresholds and it still doesn't work. Here is what I am 
> trying to change: 
> http://www.weddingclipart.com/wca/edittemplate.do?template=218069
> I am trying to change the colors of the scrolls on the wedding invitation. 
> The dark blue into a red, the lighter into a black. Yet I can't seem to get 
> it to work flawlessly. Please help. thanks

Some more thoughts on this... in my humble opinion, you cannot achieve a 
good-looking result if you change the anti-aliasing, and unfortunately 
all methods suggested so far alter it to some extent.

1) both parts of the clip art use the same hue, so they cannot be 
distinguished, in particular:

2) the anti-aliasing of the dark part on the white background uses 
colors found in the light one, and colors also used for the 
anti-aliasing of the light one

3) the anti-aliasing where light and dark intersect creates some 
intermediate colors very difficult to sort out

So a perfect cut will not be achieved without a lot of manual intervention.

However, the color of the whole clipart can be changed without adding 
aliasing by painting it over with a brush in "color" or "hue" mode 
(these modes won't affect the background) so you can change it to red 
tones fairly easily. Making the light one black will not work, because 
this will also affect the anti-aliasing pixels.Your best bet is to 
darken the dark one using the levels or curves tools, but you can't push 
it very far because this creates a light border around it (those $£à# 
pixels that are in the tone ranges of the light part...) (in other words 
you'll have to darken both parts if you want a very dark dark).

Conceal the trickery by flipping the clipart vertically :-)

Unless someone has a better solution?


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