I am getting back into PDN negatives and have started working on a curve for van dyke, can someone refresh my memory how to interpret data that falls below the straight line on the curve value locator. I remember using the pink rectangle to measure the values above the straight line but I have some values below the line. How do I use the rectangle to measure them? I have attached an example.
Scott B. Weber
Associate Professor of Photography
Department of Fine Arts
Miami Shores, Florida
305 899 4922