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I have some images that have some transparent grey pixels, and when I make the picture larger, thoose pixels are visible a little bit.

Is there a way to do this with Photoshop?

In GIMP you can select when you export 'clear color data from transparent pixels'.

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This is one of those things, the pixels can not be noncolored. They have 3 color values and alpha. Allways! thats how it works. What you wabt is to either defringe or recolor those pixels. Ofcourse different engines attack those pixels differently, yet they still have color. Thats the way pixel graphics work be it gimp photoshop, incidenttally 3d artists see this most often. –  joojaa Jul 24 at 22:00
    
maybe just make the pixels white –  user1452079 Jul 25 at 4:16
    
@jooja: what the GIMP option does is to fill the color information of the 100% transparent pixels with the current background color. Otherwise, the retain information that will be visible if one does change the alpha information on that pixels. –  jsbueno Jul 26 at 2:06

2 Answers 2

I would have to see said pixels to tell you for sure, and know whether you're trying to save to .gif format - if you are, just save your frames as .PNGs and import into GIMP, Photoshop's indexing/GIF features are annoying.

Assuming you're saving to .png:

If they're not along an edge, just use the eraser tool at max opacity on the final .PNG image. Alternately, if they're over something opaque, zoom in on each spot and blink the visibility of each layer until you find the layer they're on.

Incidentally, there's no reason under the ever-loving sun to use that GIMP function except to save file space. It only works on 0% opaque pixels, so your semi-transparent ones won't even get touched! Photoshop treats the alpha channel differently. In GIMP, erasing effects only the alpha (transparency) channel, while in Photoshop... let's just say transparency-lock a layer and using the smear tool in the 0% opacity -> 1%+ opacity direction does something pretty dang interesting.

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"except to save file space" is not such an edge use case - doubly so if you are preparing an image for the web. But besides that use case, it may be used as a privacy feature as well. Both cases make it far from "no reason under the ever-loving sun" - and the OP may be wanting one of those, if not others. –  jsbueno Jul 26 at 2:08

The GIMP option does not make what you want - they delete the RGB information on pixels that are already 100% transparent. If your pixels are visible, they are not 100% transparent. GIMP has another feature to deal with that, that I don't know if exists in Photoshop: Layer->Transparency->Threshold Alpha.

Otherwise, you could use the Curves tool, set it affect the Alpha Channel, and flatline the left part of the curve.

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