Eliminating semi-transparent pixels

[jtlapp]

How do I eliminate semi-transparent pixels from my PNG exports?

I am creating designs for T-shirts. They print on a white matte, so any semi-transparent pixels become light, which doesn't look good on a dark shirt. So I can't have any semi-transparent pixels.

I have found two approaches:

(1) Export to GIF. GIF doesn't support intermediate opacity, so this works great, except that GIFs are restricted to 256 colors. I typically only have a few colors in my images, but the anti-aliasing between colors goes through the 256 pretty fast, and my blacks end up not perfectly black. Given that T-shirt prints tend to soften over time, I want them starting perfectly black. To fix this problem, I'm then loading the GIFs into AP, flood-filling the almost-black with black, and exporting as PNG.

(2) Magic-wand select the transparent pixels, expand that path by one pixel, and monochrome dither. Unfortunately, this doesn't reach many of the pixels, particularly those adjacent to halftone dots. It also doesn't always produce the best conversion of semi-transparent to black and white. And it converts even colored pixels to black, which I then have to go through converting back to their proper color.

Is there any easy way to do this? So far (1) above is the ONLY way I've found to get the job done, and it's a bit of a pain. Thanks!

[toltec]

Apply a Curves adjustment layer. Select Alpha from the menu  then you can play around with the curve to do pretty much what you want with those elusive semis 

[jtlapp]

3 hours ago, toltec said:

Apply a Curves adjustment layer. Select Alpha from the menu  then you can play around with the curve to do pretty much what you want with those elusive semis 

Woohoo! That does it! Thank you!

I'm using a half-way stair step pattern and am getting a better rendering of text than I was relying on exports to GIF.

[tricia309]

@toltec, that was gold! Thanks so much!!!

@jtlapp, thanks so much for asking!