Whites and Blacks
In many cases the Exposure, Contrast, Highlights, and Shadows adjustments may be all that’s needed to make a good tone correction. Meanwhile, the Whites and Blacks sliders should be regarded as fine-tuning adjustments that are always adjusted last. Here, it can definitely be useful to hold down the key to reveal a Threshold analysis view, as this will allow you to set the white and black clipping points more precisely.
It should be noted that Blacks slider adjustments in Process 2012 are reversed from Process 2003/2010. With Process 2012 you drag the slider to the left when you want to crush the blacks and you drag it to the right when you wish to lighten. The default Blacks setting is now zero and the old Process 2003/2010 zero setting is now equivalent to a +25 adjustment. The other thing to note is that Blacks adjustments are also auto-calculated based on the contrast range of each individual image. Previously, with Process 2003/2010 if you attempted to crush the blacks in a bright, low-contrast image by raising the Blacks slider, you couldn’t always successfully clip the blacks. This was because with Process 2010, the Blacks slider had a fixed range and when dealing with foggy or distant hazy images it wasn’t always possible to clip the blacks successfully. With Process 2012, the Blacks range is adaptive and auto-calculated based on the image content. Where you have a low contrast image, the Blacks adjustment will become increasingly aggressive as you drag the Blacks slider towards a –100 value. This does mean though that you’ll end up with more range at the expense of some precision as you attempt to crush the darkest tones.