Contrast masking

When the contrast in a photograph is just a little too defined you want to lighten the shadows and darken the highlights. You can work on this with the levels, but the image may not contain enough information to work with. Your histogram is pretty much at its limits and/or is very complex so masking and working on certain areas are not practical. If you shoot in RAW there is plenty of scope to recover some of these details. Creating a high dynamic range photograph being the ultimate solution. But consider a contrast mask, which is quicker and gives a very different look. It has similar characteristics to the muslin style effect from the last post. It uses Gaussian blur to add or subtract light from the image.

Start with your flattened b/w image and duplicate this as a new layer with whatever software you use. The invert the image, ie make it a negative.

Now change the blending mode to Overlayer - this will bring up the shadows and reduce the highlights, but it also flattens the image. This is pretty much what you would do with a low contrast paper so no change there then. The plus side is it does sharpen the image - you are getting effectively an unsharp mask (USM)

Next, is the applying the changes to just the light by softening the edges. We do this by applying somewhere between 10 and 60 pixels worth of Gaussian blur to the negative image. Halos can form so it may be necessary to dial back the blur to avoid this.





The resultant image should now have less contrast and have lifted some of the detail and made the highlights less harsh.