Binary FX: Photoshop Tech Vault 3.0

Binary FX: Photoshop Tech Vault 3.0 | < | >

Create a "Bell Curve" Mask

How To:

Mask the shadow and highlight tonal values of an image while fully revealing the midtone values.

"Bell Curve" layer masks are useful in a number of situations - including adding noise and enhancing colour and tone with duped layers and blending modes such as soft light or overlay at reduced opacity settings. As I am from a prepress background, I prefer to work with curves in % values which will display the curve interface "upside down" compared to the standard 8 bpc 256 level reading. In the illustration below, the "bell" is upside down and resembles a "U" shape.

Creating a "Bell Curve" Mask:

1. The layer mask is often created from a Grayscale Image Mask. A simple solarizing curve is applied to the mask channel to create the required positive/negative effect on the masks tonal levels.

2. The white highlight 0% endpoint is raised to the same tonal level as the shadow endpoint 100% (0%>100%, 255>0).

3. The midtone point is then taken down to fully reveal the midtones (50%>0%, 128>255). This technique will burn out the endpoints and fade to full opacity in the midtones.

Simply invert the curve in steps 2 and 3 or invert the tonal levels of the final mask to reverse the masking effect.

Tip:

Layer Style Blending Options Blend If sliders are a useful addition, or sometimes a viable alternative to layer masks. Alt/opt click on the blend if slider triangle to split the tonal range to provide a smooth blending transition.

Related Links:

How To: Create a Grayscale Image Mask

< | > | ^ | How To Home | Home