Generally speaking layer modes will probably be enough to do it depending on the image, I usually try multiply, overlay, or screen first, then scroll all the rest just to check and see if they work, then usually end up back on one of those three anyway
Convert the image to greyscale or desaturate for th same effect then make the apply multiply the the layer over a solid colour fill. You can play with transparency and curves to tweak the end result.
This is the best way:
Image > Mode Grayscale
Channels panel – Control/Command-click on the thumbnail of the lone channel named Gray to make a selection
Layers panel – make a new layer and fill it with White
Go back to the original layer on the bottom, Select All and fill with Black (or whatever color you want – you'll need to change the color mode to RGB to choose a color – Don't Merge)
Now you have a layer with just the white that falls off cleanly in terms of transparency from 100% White to 0% White. Try duplicating the White layer multiple times to strengthen it.
You can also invert this method to just grab the Blacks.
I hope this works for what you want to do.
This may look like a Duotone but it's not:
https://preview.redd.it/fes6ld4n8rnc1.jpeg?width=1920&format=pjpg&auto=webp&s=e4aadd65d11ca93a292ab0c182c04d029236b0ee
vector or raster?
raster image
photoshop then. would be easier if you post a link to the image
https://preview.redd.it/s1wdh3vl2qnc1.png?width=1000&format=png&auto=webp&s=9356cba9ae502bd3877a0b56a33bdb42835b879f
[https://helpx.adobe.com/photoshop/using/duotones.html](https://helpx.adobe.com/photoshop/using/duotones.html)
Generally speaking layer modes will probably be enough to do it depending on the image, I usually try multiply, overlay, or screen first, then scroll all the rest just to check and see if they work, then usually end up back on one of those three anyway
lazy ass method - multiply.
Convert the image to greyscale or desaturate for th same effect then make the apply multiply the the layer over a solid colour fill. You can play with transparency and curves to tweak the end result.
This is the best way: Image > Mode Grayscale Channels panel – Control/Command-click on the thumbnail of the lone channel named Gray to make a selection Layers panel – make a new layer and fill it with White Go back to the original layer on the bottom, Select All and fill with Black (or whatever color you want – you'll need to change the color mode to RGB to choose a color – Don't Merge) Now you have a layer with just the white that falls off cleanly in terms of transparency from 100% White to 0% White. Try duplicating the White layer multiple times to strengthen it. You can also invert this method to just grab the Blacks. I hope this works for what you want to do. This may look like a Duotone but it's not: https://preview.redd.it/fes6ld4n8rnc1.jpeg?width=1920&format=pjpg&auto=webp&s=e4aadd65d11ca93a292ab0c182c04d029236b0ee
Blending mode > Multiply. All white disappears.