In this example, the tone curve information has been applied to the raster data (RIPed data).
If you change any settings that require RIP processing to be performed again such as simplex/duplex settings, re-processing causes the raster data to be discarded and recreated, and therefore the tone curve information applied to that raster data is also discarded.
15 minutes or less
If using ImageViewer to operate the tone curve, do so just before printing. When changing settings that require RIP processing to be performed again, do so before adjusting the tone curve.
To change the tone curve just before printing, use ImageViewer to apply a previously edited tone curve (stored as dsv data).