Both PDF2IMG and Adobe Acrobat offer an Overprint Preview (OPP) option. Sometimes in printing a color in a graphic or image is printed directly on top of another color. The color on top can be opaque, and completely cover, or “knock out,” the color beneath. Or it can be a partially transparent, and blend with the color underneath. In this case the color is said to be over printing, and the OverPrint Preview feature in Adobe Acrobat allows you to see the result of the overprinting in the PDF document.
By default, Overprint Preview is turned off in Adobe Acrobat and Adobe Reader and disabled in PDF2IMG. To avoid seeing a difference between your input PDF document and your output graphic files, make sure that OPP is either turned on or turned off for both the Adobe Acrobat software where you review the original PDF document and for PDF2IMG. The OPP setting needs to match for both software products.
To turn OPP on in Adobe Acrobat, from the Edit menu select Preferences and Page Display. For the dropdown menu that appears for “Use Print Preview,” choose Always.
To enable OPP in PDF2IMG, use the pdf2img_set_OPP API call or the -OPP command line statement.
Visit this page on our Developer’s site to learn more.
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