Converting a png to exactly two colors (black & white), not grayscale

[deltaquattro]

Hi,

 

I have an image which is a technical drawing. The original image has a white background (which I need to keep) and multiple colored lines, which must be all converted to black (think of it as the technical drawing of a machine). I can't find how to do it in Paint.NET 4.0.6. Using Adjustments\Black & White gives me back grayscale, which doesn't cut it: I need all lines to be the same (black), not some lines to be darker, and some others to be lighter (a few are so light, I can barely see them). I also tried playing with brightness & contrast, but I end up messing the background, which is white originally, and must stay so. Any suggestions? 

Edited October 22, 2015 by deltaquattro

[racerx]

After you convert ti black and white, use the curves adjustment tool. Click a point in the center and move it down. You can also use the "Threshold" plugin by Ed Harvey to do the same thing.

[deltaquattro]

Nice! It worked fine, thanks. In meantime I found another solution: Adjustments\Hue & Saturation -> maximize Hue and Saturation, then Adjustments\Black & White. I don't know what's happening exactly but they both work

[TechnoRobbo]

Curves under the adjustment menu - you can decide what shade go white or black and define multiple vertical adjustments on the graph

[Riddley]

Bruh, just use the Brightness/Contrast Adjustment; Max out the contrast, and if the white background gets messed up, raise the brightness.

Edited October 23, 2015 by Riddley