Grey Step Wedge

To create a grey step-wedge in Photoshop:

open a new file in greyscale mode;
set the canvas size to approximately 6" x 4" format at 300 dpi;
fill the background with 100% black with white as the foreground colour;
select the gradation tool to create a linear gradient (foreground to background) with opacity 100% in normal mode;
click at one end of the image and drag the cursor to the other end of the frame;
using the rectangular marquee tool, draw out a rectangle to define the dimensions of the step wedge, being sure to include the whole range of the gradient;
select image - adjust - posterize to break the gradient in to steps;
enter 21 as the posterization value and click OK - this creates a step-wedge from 0% to 100% in 5% increments;
a step-wedge in 10% increments can be created by using a posterization value of 11;
the value of each step in the wedge can be checked using the eyedropper tool and the show info window;
label each value on the wedge with the type tool; and
flatten the image and save.