Dear Sir or Madam,

my name is Tjaša and I am studying at the university of Natural
Sciences and Engeneering in Ljubljana (Slovenia). I am allready
writing a degree in Graphic technology about PDF/X standards and
differences between them. I made my own test form to compare different
PDF/X standards and different print devices. I have exported differend
PDF/X standards from Adobe Indesign CS3 and then I have printed them
on different printers (digital printers). Although I was looking for
many answers on the internet I didn't find out why there are
differences between standards in LAB (differences between PDF/X-3 and
PDF/X-4, as I traved an information which mentioned that PDF/X-3 and
PDF/X-4 interpret LAB colors in the same way). I also find out that
PDF/X-1a and PDF/X-3 are smilar and PDF/X-4 and other presets in Adobe
Indesign (such as press quality and high qualilty print) are similar
too in interpreting the LAB colors. I just didn't find out why. The
same problem happened with overpint. Only PDF/X-4 and high quality
preset were printed suitable. The PDF/X-3 and PDF/X-1a didn't
recognize the overprint. Similar happened with pictures (one in CMYK
and the other in RGB color space).. PDF/X-3 made them really similar
while PDF/X-4 made RGB printed pictures much more bright instead they
have the same setting about converting colors during export.

Is it possible to explain this with differences between standards or
it depends on the settings of the RIP?

I will really apreciate any answer you could give me. It wiil be very helpful.

Best regards

Tjaša Uršič