I shot the following photo with Nikon D3100 + Nikkor 50mm 1.8f G.
I shot this with the Monochrome option of the camera.

enter image description here

I use Gimp for post processing.

enter image description here

I sharpened this with the Unsharpen Mask option with:
Radius set to 6.5
Amount set to 0.65
Threshold set to 0

and I raised the Contrast till 20.

I don't like the results. It looks over processed to me. I want it to look sharp, and black and white but not over processed.

How to convert a dull monochrome photograph into a sharp black and white photograph with great contrast?

  • \$\begingroup\$ What do you mean by a "black and white" photograph as opposed to "gray"? Your final example still has multiple shades of gray in it - a truly black and white photo would have only RGB(0, 0, 0) and RGB(255, 255, 255) in it. \$\endgroup\$
    – Philip Kendall
    Jul 10, 2015 at 8:21
  • \$\begingroup\$ @PhilipKendall I don't know what are the correct words but by gray I meant "dull". \$\endgroup\$ Jul 10, 2015 at 8:26
  • 1
    \$\begingroup\$ perhaps do the black and white conversion in post processing with the original photo in color. There you change each color channel, which simulates using colored filters with a monochrome camera setting? \$\endgroup\$
    – fluf
    Jul 10, 2015 at 8:29
  • \$\begingroup\$ @fluf I said I shot this in monochrome. I have no colour version of this. \$\endgroup\$ Jul 10, 2015 at 8:29
  • \$\begingroup\$ @TheIndependentAquarius I know its not a solution to your current problem but it can be a "better" route in the future. You currently do not have enough information in the photo to do per channel changes unless you have a raw file as well \$\endgroup\$
    – fluf
    Jul 10, 2015 at 8:34

2 Answers 2


Unsharp Mask will increase contrast, but it works by exaggerating local differences. You probably do want to use Unsharp Mask in the processing of an image like this to increase the amount of contouring, but it's not the best way to go about fixing the major tonal issue.

You can't really say that there isn't enough total contrast in the image, since you have blown-out white areas and some absolute blacks. The problem is that there isn't enough contrast in the "interesting" parts of the picture — the hair isn't dark enough, and the part of the white shirt that isn't a highlight isn't quite light enough. You can use a curve to fix that (I don't have Gimp, and I figure that Gimp users are pretty tired of seeing Photoshop examples everywhere, so I'm using the Curves adjustment from Paint Shop Pro 9 just to show that it doesn't have to be Photoshop to work):

curves adjustment dialog

Note the "S" shape; that increases the amount of contrast in the mid-range of tones, making things that are not quite black darker and things that are not quite white lighter. That will make the picture "pop" quite a bit more than it does with the original tones:

Image with curve applied

The curves adjustment can go quite a bit further than I've gone here without damaging the image in any way. Honestly, the adjustment looks a lot bigger with the before and after in the same place (turning the layer with curves on and off) than it does here, so I probably should have been more extreme with the example. I was leaving room for the next step...

If the shapes aren't quite "3D" enough at that point, you can use a large-radius Unsharp Mask at a fairly low strength to boost the contours a bit, but whether you want to (I probably would) and how much/what settings is a matter of taste and personal preference. But you'll be starting with an image that has a better contrast range where you want it, so you shouldn't wind up with something that looks over-processed.


Although I use Lightroom and Photoshop, I am sure that my preferred method of sharpening can be applied in GIMP

The best way I have found to achieve that Sharp and Contrasty Black and White look is through an initial tonal adjustment and then a High Pass Filter.

First step is to gain the maximum range of tones. Can be done with Sliders or Curves.

  1. Watching the Histogram, bring highlights down as far as possible without clipping Next, increase/Decrease the shadows and increase whites to just enough to provide a little extra depth

  2. Bring the black slider slightly down (Increasing Black) to provide a little extra depth

  3. Ensure that no clipping occurs at either end of the histogram

The next stage is the sharpening

  1. Create a "duplicate layer" of the background

  2. Apply a high pass Filter Radius of between 1 and 10 pixels - go with what looks acceptable to you - Too high and you get the Unsharp Mask Look which is not what you want.

  3. Overlay it or apply Linear Light. Overlay is a softer approach and Linear is a harder approach.

  4. The next thing is to create another Duplicate Layer of the Background and move this layer to the top and make it active.

  5. Apply a Layer Mask on this Layer

  6. Choosing a very soft brush, with an opacity of around 25%, on the Mask, start to paint in Black around areas that need sharpening. The lower the opacity, the more control. If a mistake happens, just brush over in White to revert the process.

  7. Once the desired sharpness levels have been reached, bring down the Opacity levels of High Pass Filter Layer to make further adjustments.

Finally, you can adjust the Curves once more to reach your desired look

I have attached an example and paid special attention around the little girls face and the blades of grass to demo how you can control with this technique!

Edited Picture Attachment

Please do note, I have over exaggerated on all adjustments taking into consideration that the final result may be an overkill, but this is to emphasis the difference between Unsharp and High Pass Filter.


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