Grey Step-Wedge Creation

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.