Split grading combines a high contrast image with a low contrast image for a better tonal range in a black and white photo. In other words, split grading allows you to increase contrast without losing highlight or shadow details. This quick tutorial shows you how easy it is to boost the range of a flat image. This is a fun trick to know. It is extremely easy, and although you won't need to use it on every image, it can come in handy.
A lot of tutorials will begin with a color-to-black-and-white conversion that uses the "desaturate" command. I have already shown you that the channel mixer is a far better method. I mention this because if you begin with desaturate and then use split grading the difference in the final image will be more dramatic. Here, because we begin with a better conversion, the difference is more subtle.
1. Open a color image that you want to convert to black and white.
2. Change to black and white by using channel mixer as learned at the beginning of month, and flatten your image.
4. Deselect the "high contrast" layer by clicking the eye icon (layer visibility) in the layers palette. With the "low contrast" layer active, select Image-->Adjustments-->Brightness /Contrast from the top menu bar.
NOTE FOR ELEMENTS USERS: The only that changes with this tutorial is that you must select Enhance-->Adjust Lighting-->Brightness/Contrast as in the following screenshot:
In the dialog box, lower the contrast to -50 or until there is visible detail in the shadows and highlights.
6. With the "high contrast" (top layer) active, change the blending mode (in the layers palette) to "overlay."
7. Adjust the opacity of the top layer until you have detail in the highlights while still retaining contrast.
If your channel mixer conversion was good to begin with, your final image will have more detail in shadows and highlights. Here are the before and after images:
The "before" image (above) already has a good tonal range, but...
The "after" image shows better texture and highlights. Look at dirt around the window or at the bottom of the image. There is better overall contrast and the highlights haven't become too extreme.