Curves
The Curves window plots the positive image against the actual negative.
The X axis is the logarithm of the positive image file in 16-bit mode. Each gridline corresponds to a step in the stepwedge and test strip shown below the plot figure.
The Y axis is the 16-bit logarithm of the negative between the RGB values that print just black and just white.
The unprofiled negative is plotted as a straight dashed blue line. The yellow line plots the corrections made to the toe and shoulder of the print made by the profile and any other modifications made by the user.
The curve can be overwritten and amended by clicking on the plot to build a new curve. Clicking below the preset curve darkens the print; clicking above lightens it. Points can be added anywhere, between existing points, dragged by holding down the left mouse button and dragging, and can be removed by right-clicking. The only limitation is that they cannot be closer than approximately half a grid space to each other.
The new preset is saved by clicking on or just below the line marked “Clear Film,” which corresponds to the negative pixel value RGB 255.
Note that the negative scale is inverted, so that clear film is at the bottom of the plot and the curve slopes up from left to right as the negative gets darker in order to match the traditional DlogE curve.