Save duotones as separated PostScript DCS files, if you create them in Photoshop 3.0 or 4.0 or Corel PhotoPaint for placing into QuarkXPress software or PageMaker . These graphic software applications generate the duotone EPS files in such a way that spot colors are preserved only in separated PostScript. Saving as composite PostScript will not preserve spot colors. The image will be converted to process colors.
Resave duotones created in Photoshop 5.0 using Photoshop 5.0.2 or later. The earlier version contains a bug that prevents duotones from working correctly on PostScript 3 devices. The free upgrade to version 5.0.2 is available from http://www.adobe.com.
Duotones created in Photoshop 5.0.2, or later, saved as DCS, and placed in a page layout application such as QuarkXPress software or PageMaker should be saved as composite PostScript with OPI comments (thin PostScript). Alternatively, you can save as separated PostScript and choose to include images (fat PostScript). Prinergy Evo software can perform trapping and color handling functions on composite input files only.