Adding Dust to Glass through a JPEG Texture

Okay im currently in the process of trying to make a photorealistic golden clock for a project i am working on. With the modelling and basic material set ups complete i decided that in order to improve realism i would add some dust/fingerprints to the glass part of my model, via a ‘dust texture overlay’. The only downside to this is that the overlay is in JPEG format and consequently doesnt have an alpha channel.
I was wondering if there was any way inside blender to remove the black background of this texture via the cycles nodes. I wondered if the Screen node would work (as it does in photoshop) and remove the black leaving the white dust but so far all efforts have been unsuccessul.
All help would be appreciated as i feel the answer is just so obvious and im simply missing it :confused:

You could use the b/w texture as an input for the Fac of a mix shader node…?

You might be able to do it in GIMP if you do not have P.S. GIMP is free. Has magic wand, many tuts out there on remove BG in GIMP.
I do not know if Blender has that ability, so that was a resolve

Wow, thank you for the quick replies! Attached is my node setup for the glass without the added texture. @IkariShinji i cant wrap my head around how to input the texture as the fac for the mix shader, whilst still keeping it from casting shadows (as it is currently doing so).

Simple version (uncheck ray visibility > shadow in the object tab if you don’t want shadows):

Transparent shadows instead of caustics. Transparent shader must have a color darker than white, otherwise you get the same result as unchecking shadow ray visibility (no shadow at all), but it renders slightly slower:

Its easy to add fingerprints. I made the fingerprints blue so you can see them better in this example.

I would use a particle system for the dust like I did here: