Entering Numbers

After you've created a point, it will appear as a solid square. This represents the point that's currently being edited. The Input and Output numbers at the bottom of the dialog box indicate the change this point will make to an image. The Input number represents the shade of gray that's being changed. The Output number indicates what's happening to the shade of gray—the value that you're changing it to. As long as the point appears as a solid square, you can type numbers into the Input and Output fields to change the location of the point (Figure 6.59).

Those numbers can be very useful. We'll end up depending on them once we get into the chapter on color correction (Chapter 8). But for now, let's see how they can be useful when attempting to change the brightness of an image. Remember that you can click on your image and a circle will appear in the Curves dialog box that indicates what part of the curve would affect the shade in that area? Well, you can also Command-click (Mac) or Ctrl-click (Windows) on your image and Photoshop will add a point where that circle would show up. So, what if you'd like two areas of your image to have the same brightness level? Command-click or Ctrl-click one of them to lock in its brightness level. Then, before you release the mouse button, glance at the numbers at the bottom of the Curves dialog box to see exactly how bright that area is. Command-click or Ctrl-click the second area, and change the Output number to match that of the first object (Figure 6.60). The bar chart will be the same height in both areas, which means that both areas will end up with the same brightness. But you have to be careful when doing this, because the bar chart will flatten out between those two points. When that happens, there won't be any detail in those shades, so other parts of your image might seem to disappear (Figures 6.61 and 6.62).

You can hold down Option (Mac) or Alt (Windows) to set options such as the Blending mode when you are creating an adjustment layer.