Copying: Issue with transparency

Forum|Forum|8 years ago
April 7, 2017
3 replies
861 views

Hello guys,

this is a very basic problem that I just happen to never have been taught to deal with, so sorry for asking such an elementary question.

In short, when you select and copy/paste (or cut/paste) an element from one background to another, how do you deal with the original background shining through?

In the below example (taken from a much larger file) I had used color range selection to find all the black text on the page (which had a mostly white background, though some of it was within colored images, too) and pasted it onto a background of withered paper.

Of course, now I got the original white background shining through at the letters' edges (indicated by the arrows). What are the standard methods to avoid this?

This topic has been closed for replies.

rayek.elfin

Legend

The best approach is to 'unmultiply" white. Surprisingly enough, Photoshop lacks a function like that, however. There used to be a plugin to handle this (ayato@web ), but it is no longer compatible, I believe, with the current version. The FilterForge plugin works, though. (Although the issue is that it only works with black - see below for alternatives)

The trick is to invert the white page with black text first (negative), then apply the unmultiply black plugin, and invert back. This will remove the white from the anti-aliased pixels, resulting in perfect edges that are true to the original.

Of course, D Fosse's solution will work just as well since the text is pure black only. But what if colors are present? Or it's not pure black or white?

Gimp, Krita, and PhotoLine all have a built-in 'unmultiply' ('Color to Alpha/Transparency') function, though. You could download Krita (open source and free!), open the image(s), and use the simple "Color to Alpha" filter to remove the white (or any other background colour), and retain the exact anti-aliased quality of the lettering - in particular when any coloured areas are included, multiply blend mode will prove to be less helpful.

Check out the example in Krita: removing the black without a "color to alpha/transparency" option takes much more time, gets technical, and is generally less effective. With Krita it is super simple and effective. The command is found in Filters-->Colors-->Color to Alpha menu. https://krita.org/en/

D Fosse

Community Expert

rayek.elfin wrote
Of course, D Fosse's solution will work just as well since the text is pure black only. But what if colors are present? Or it's not pure black or white?

It's an interesting point, and this is a potentially very useful function that isn't too difficult to implement. I thought it was, but then a simple action came up in a thread here some time ago. I recorded the action and it works perfectly.

Let's see if I can find it...

...ah, here it is: https://forums.adobe.com/thread/1395311

D Fosse

Community Expert

I'd just set the text to Multiply blend mode.

Chuck Uebele

Community Expert

You can try making the selection, moving just the selection, then filling the selection with black. Or copy paste the selection, then lock the transparency on the pasted layer, and fill with black.

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