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Hola, no se si es un bug o desconocía este comportamineto. Recientemente me he encontrado con un problema de impresión. Un logotipo con una tinta directa, con un color de 15% de negro. Para evitar problemas al expotar a PDF para que el cliente lo previsualice como debe quedar, le pongo el efecto multiplicar, ya que en algunas versiones de PDF la opcion de sobreimprimir no queda bien. Mi sorpresa ha sido que al mandarlo a imprimir con el perfil PDF/X-1a:2001 ese matiz de 15% se ha convertido en una cuatricromía que ha salido en todas las planchas.
Como digo no se si es un bug, pero para mi un color directo debe ser siempre directo y no convertirse en un CMYK porque tenga el efecto multiplicar
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Hi mastres,
in this case you cannot avoid overprint.
If done right technically for a printer that uses 1 spot color plus Black your applied effect will also work with overprint.
If you want to simulate overprinting or the transparency effect you will either end up with a CMYK or RGB result for all colors. You cannot have a PDF for all PDF reading applications that does the visual appearance and the technical aspect ( spot color + Black ) right at the same time.
Regards,
Uwe Laubender
( ACP )
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Overprint in a PDF should not be a problem, some non-Adobe PDF viewers might not correctly display overprinting and the Acrobat & Adobe Reader page display preference to use oveprint preview should be set to "Always". Use the Acrobat Output Preview tool to check separations before sending a PDF to your printer.
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If your customer has a PDF reader that cannot simulate overprint right, I suggest you export two PDF files.
One for offset printing only and one for viewing only. This export settings will get you the PDF for viewing only in all PDF viewing applications:
It converts all colors to sRGB, because there are PDF viewers that have also trouble viewing CMYK colors right.
Regards,
Uwe Laubender
( ACP )
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Gracias por las respuestas, he hecho alguna pruebas y no existe el problema que comentaba, no se por qué me pasado en el trabajo, pero no he sabido reproducir el error.
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Multiplying black or a percentage of black should create the equivalent of an overprint, and it would stay unchanged no matter what the Acobat overprint prefs are.
The black and the multiplied area might convert to 4-color in a few cases. If the PDF/X-1a Output Destination is set to something other than Document CMYK, or the document’s Transparency Blend Space is set to RGB.
Here the Overprint for the 15% Black fill is unchecked, but it is overprinting because of the Multiply blending mode
An Export to default PDF/X-1a:
Here the Output Intent conflicts with the InDesign document’s assigned profile. This would also happen with a RGB Transparency Blend Space