convert -density 300 -brightness-contrast 0%x90% JGld-ReadyRefSheets.pdf readyrefsheets-contrasty.pdfThat grinds my machine to a halt for several minutes, so you might want to lower the priority level of the process with nice. If you have an older version of ImageMagick, you may be able to achieve similar results using the
-contrast-stretchoption instead of
-brightness-contrast. If you have a better way to achieve similar results, I'd like to know. Thanks.