Printing Grayscale images with transparent whites over a spot color background

[Lynn_T_Coakley@adobeforums.com]

Adobe Photoshop 6.0
Adobe Illustrator 8.0.1
Mac OS 9.2
Power Mac G3 (beige tower)
Printer: GCC Elite XL 616

Desired Results:
I have a grayscale image in Photoshop 6.0
I want to import it into Illustrator 8 with transparent whites
I want the grays and blacks of my photoshop image to overprint a solid pms background with the whites transparent

My Questions:
What mode should my photoshop image be in?
What file format should I save my photoshop image as?
When placed in Illustrator 6.0 how do I make sure the whites of the photoshop grayscale do not knock out the pms behind it?
Should I improt my grayscale image into Illustrator to make the whites transparent or should I try to have my grayscale image and my spot background in Photoshop and work in Channels? If so, how do I do this?

What I have attempted:
I have tried saving my photoshop files as a grayscale eps file.
When I import the file into Illustrator I see the white background of the grayscale image.
I put the grayscale image on its own layer
In the Attribute window I click on Overprint

Two problems result:
Despite clicking on Overprint for my layer when I go back and forth between my different layers I lose the overprint optiong that I clicked. (On another layer I want my black type to knock out which is the default right?)

When I print out seperations on a postscrip printer (I have the ppd selected), the white behind my grayscale photoshop image is knocking out of my spot color. I want the whites to be transparent and the blacks to overprint.

please help.
thanks

[Dee Holmes]

I think you're better off with John Kallios to handle these questions.

But in the meantime try placing a .tif

[John_Slate@adobeforums.com]

Do you have any layout software like InDesign or QuarkXpress?

The easiest way to do this is to save as a grayscale tiff then place in a layout and colorize the background of the box to your PMS.

In QXP the picture will overprint by default (in a separated workflow)

In ID you have to force the picture to overprint either by the overprint command or multiply.

Otherwise you can add a spot color channel, in Photoshop and fill with 100% tone, but that means saving as a DSC2, and if you do that you should definitely NOT place the DCS2 in Illy.

Or... you could convert to duotone from grayscale and in the ink transfer dialog for you PMS set 0% to 100%, to get a solid PMS, then save as .eps.

The duotone you can place in Illy, but it MUST be linked. If you embed it, it will convert to CMYK on output.

And there are other ways too, but not with the version of Illy that you have.

[John_Kallios@adobeforums.com]

John Slate's intructions regards colorizing the grayscale image but I am under the impression that you desire the image to remain grayscale and just overprint the background.

John Slate's advice is still accurate in that this is easier to accomplish in InDesign or Xpress. (or later versions of Illustrator will slight workarounds)

But, to accomplish this in Illustrator 8, you must first be aware that Illustrator 8 does not possess the ability to set a raster image to overprint. (even though you can select the attribute, it does NOT work and future versions of Illustrator grayed out the function)

So, to accomplish this, take the background and place it above the raster image and set the "background" to overprint.

Not a elegant solution.

[John_Slate@adobeforums.com]

John Slate's intructions regards colorizing the grayscale image but I
am under the impression that you desire the image to remain grayscale
and just overprint the background.




....I did say colorize the background of the box...

[John_Kallios@adobeforums.com]

Sorry, I missread your post John. I seem to be batting 0 today. :)

[John_Slate@adobeforums.com]

'sOk, but while we're on the subject, have you ever come across a composite workflow that does not knock-out the background tint printed from QXP? ...as opposed to printing the same thing as separations you get a flat tint in the background color.

....and did that whole issue change in IDCS or do you still have to do the multiply thing?

[John_Kallios@adobeforums.com]

The same issue resides with CS and placing into QXP.

CS still does not have the ability to set a raster image to overprint. Using multiply will work with internal elements, but when saving to eps while preserving overprints, the multiply is not preserved for external elements due to it really being a form of transparency and not a overprint.

If saved as .ai or pdf (1.4 compatibility+ ) then the multiply is retained for placement in InDesign. Not QXP though. The same tired workarounds will still need to be employed for QXP.