Transparency Dithering/Screen-Door Effect

[destdehat]

Hello! This is my first post here, so I apologize if it's in the wrong category or a badly explained question, but I wanted to know;

 

How would I make an effect like this, where instead of alpha transparency, the pixels start to gradually get more spaced out, simulating transparency?

I'd like to specifically apply this effect around the image, like in this image, but with the dithering effect:

 

 

 

[frio]

A couple options come to mind.

 

Easy but chaotic and not very configurable: Alpha to Dots

Less easy but configurable: extract the alpha mask, dither that with one of the several b/w dithering plugins, then replace the original alpha mask.

• Alpha extraction: Alpha to Gray from BoltBait's plugin pack
• Dither: BoltBait's pack has Floyd-Steinberg dithering, Halftone dithering from Ed Harvey's pack, QuantDith can do several styles of dithering, including ordered ones.
• Reapply alpha: BoltBait's pack has Apply Alpha Mask. There's this other Alpha Mask if you want to paste the mask from clipboard.

 

Top left: original, top right: alpha to dots, bottom left: halftone, bottom right: QuantDith.

Edited November 26, 2023 by frio

[Rick Brewster]

3 hours ago, frio said:

it can result in color deterioration at low opacities*

 

Are you referring to transparent colors, where A=0 and the RGB channels are thus flattened to zero?

[frio]

24 minutes ago, Rick Brewster said:

Are you referring to transparent colors, where A=0 and the RGB channels are thus flattened to zero?

 

That, and back the last time I checked after the plugin was updated to better preserve colors, it still would oversaturate low-alpha pixels sometimes, but I've long forgotten how/deleted the files I got those results on. I just reinstalled the plugin to double check and am not seeing any of the above problems anymore (even colors in zero-alpha pixels are preserved) so I'll revise my post accordingly.

 

Edit: looks like the file date on the apply mask plugin was shortly after I last checked in early-mid summer so I missed an update, my bad.

Edited November 26, 2023 by frio

[destdehat]

On 11/26/2023 at 2:54 PM, frio said:

A couple options come to mind.

 

Easy but chaotic and not very configurable: Alpha to Dots

Less easy but configurable: extract the alpha mask, dither that with one of the several b/w dithering plugins, then replace the original alpha mask.

• Alpha extraction: Alpha to Gray from BoltBait's plugin pack
• Dither: BoltBait's pack has Floyd-Steinberg dithering, Halftone dithering from Ed Harvey's pack, QuantDith can do several styles of dithering, including ordered ones.
• Reapply alpha: BoltBait's pack has Apply Alpha Mask. There's this other Alpha Mask if you want to paste the mask from clipboard.

 

Top left: original, top right: alpha to dots, bottom left: halftone, bottom right: QuantDith.

 

How'd you achieve that effect with QuantDith (bottom right)?

[destdehat]

Nevermind, I figured it out, thanks!

[frio]

7 minutes ago, destdehat said:

How'd you achieve that effect with QuantDith (bottom right)?

 

Set palette to BW, adjust the brightness/contrast to get desired coverage of the gradient.

Post-contrast is a bit weird and can't honestly figure out what it's doing, but pre/post-brightness both do about the same, and pre-contrast acts like contrast would usually. 

 

Also try the different dither patterns, ordered 2x2 might produce something very similar to what you had in your original images.

 

Edit: Okay I guess I was late by a couple seconds for this, heh!

Edited November 27, 2023 by frio

[lynxster4]

Thanks @frio! This would be great for making various brushes. 🙂