Big Unsharp Mask

< 

This is a procedure that I apply to almost all of my images. I picked this up from Russel Croman's website. Contrary to it's name, the Big Unsharp Mask is more about increasing the contrast of an image than increasing it's sharpness. I think a Big Unsharp Mask produces a much more satisfying contrast enhancement rather than simply stretching the histogram.

Before image:

First let's bring up the Levels dialog:

The Output sliders at the bottom of the dialog control the shadows (black slider to the left) and the highlights (white slider to the right). We want to pull the highlight or white slider on the right towards the left until the Output level display above it goes from 255 to somewhere between 255 and 200. In this case we'll pull it almost all the way to 200.

You'll notice that instead of picking up more contrast, the image actually appears to have less contrast. This is normal for this procedure. Next we'll apply the Unsharp mask:

Adjust the Unsharp Mask sliders as follows: Threshold 0 and Radius 250.0 pixels. Then adjust the Amount to somewhere between 1 and 50%. In this case we'll adjust it to almost 50%:

I recommend fading back most effects applied to images:

Here I fade the image back to about 83%:

Here is the image after the procedure is finished. Move the mouse over the image to see the image as it was before the procedure: