standart overprint mode

[a-pap]

Hello everybody,
I am wondering if there is a real diference between seting an object standard overprint mode and seting to knockout. For example, if i have a 4 color backround and foreground text C30, Black100. I can't find any defference between those two, so where the standard overpint mode can be used?
Also does anybody know how i can change the overprint mode in applications (AI, ID etc)

 

[kyle]

For a spot object, either mode should have the same result. For a CMYK object, the Illustrator overprint mode yields the familiar result, whereas "standard" overprint mode will knock out other CMYK but overprint spot inks. I don't think any current or recent Adobe applications discriminate between the modes and always use the Illustrator mode. Opening a PDF containing a standard mode object with Illustrator CS4 and resaving changes it to Illustrator overprint mode.

 

[Lukas Engqvist]

Many RIP's are configured so that CMYK objects that are not 100% black will knock out. Where and how are you viewing the result? Are you viewing it with overprint preview? A 30% cyan with over print will give you flat 30% in Cyan in the RIP and 100K will give you 100K but Magenta and yellow should be constant in your RIP. If you use digital printing usually all overprints are ignored, and your option is to "simulate overprint".

 

[a-pap]

I am viewing the results in output preview in acrobat 7 and in RIP (apogee).
For editing pdfs i use pitstop7 (changes overprint mode), and i recently read the user manual about different modes of overprinting.
I am confused about the difference between overprint OPM 0 and Knockout.
In the previous example i gave, even if i set font to overprint OPM 0 or knockout it i get the same result. Anyway thanks for reply.

 

[kyle]

Knocking out just means the overprint attribute is not applied. If the object is CMYK and everything underneath is CMYK, then overprinting with "standard" mode would be the same as knocking out. One of the elements involved must be a spot color for the standard mode to make any difference.