How do you make an image truly monochromatic, with no translucency?

[Xiard]

I have various images that need to be made monochromatic (icons for an app).  The original image has anti-aliasing, so there are lots of translucent pixels on the borders of the lines.  It is very, very difficult to tell the difference visually between a pixel that is completely transparent and one that is 99% transparent.  The only values I can use for pixels in the image are #00000000 (completely transparent) and #FFFFFFFF (fully opaque white).  Any pixels of any other value causes the image to be rejected.

 

Is there any effect I can apply or process I can go through to make all pixels that are mostly transparent become completely transparent, while pixels above a threshold become completely opaque white?

[Red ochre]

http://forums.getpaint.net/index.php?/topic/25193-alpha-threshold-new-plugin-16th-aug-2012/

 

Hope that helps

[Xiard]

Great!  Thanks!

[toe_head2001]

Edit: ...great... I didn't see the other thread...

 

Run this in CodeLab. Pixels that have an opacity of 50% or less will be made completely transparent. Pixels over 50% will be made solid (100% opacity) white.

void Render(Surface dst, Surface src, Rectangle rect)
{
    ColorBgra CurrentPixel;
    for (int y = rect.Top; y < rect.Bottom; y++)
    {
        if (IsCancelRequested) return;
        for (int x = rect.Left; x < rect.Right; x++)
        {
            CurrentPixel = src[x,y];

            if (CurrentPixel.A < 128)
            {
                CurrentPixel.A = 0;
            }
            else
            {
                CurrentPixel = Color.White;
            }
            
            dst[x,y] = CurrentPixel;
        }
    }
}

Edited January 3, 2016 by toe_head2001

[Red ochre]

AlphaThreshold doesn't change the AA'd pixels to white so your contribution may not be in vain.

[Ego Eram Reputo]

Duplicate threads merged.

[Rick Brewster]

Another way to achieve a monochromatic effect is to use Adjustments -> Black & White followed by Adjustments -> Posterize, and set the sliders to the minimum value (2).