

Columns: This lets you resize by the number of columns, an arbitrary unit defined in Preferences > Units & Rulers.Picas: One pica is equal to 1/6th of an inch or 12 points, and it’s used most frequently in design for print.In a 72-DPI resolution image, one point is equal to one pixel. Points: A point is a unit of measurement common in typography that is equivalent to 1/72nd of an inch.

Inches, Centimeters, Millimeters: These are standard measurement sizes that only apply when an image is printed, and they are related to the image’s DPI.Pixels: This lets you specify exact pixel dimensions for the resulting image size.For example, using 50% as the target image size makes the image half of its current size.

