Photoshop Grayscale conversion showing up as CMYK in Acrobat

[prepress cindy]

Why is it when I have a color pdf, open in Photoshop, convert to grayscale then open in Acrobat it shows as CMYK? I've tried several settings when saving and it all comes out the same.

 

[Greg_Firestone]

Hi Cindy,

I apologize for not answering your question and asking another one instead but I have to ask why are you opening the PDF in Photoshop? It's not a good idea and can hurt the overall quality of the file.

When you say it shows up as CMYK in Acrobat, do you see this in "Output Preview"? Is there actually data on the plates?

Regards,
Greg

 

[gordo]

When you say it shows up as CMYK in Acrobat, do you see this in "Output Preview"? Is there actually data on the plates?

I just tried this in CS3 and the greyscale PDF out of PShop is CMYK in Acrobat and has image data in all 4 channels.
Open the greyscale PDF back with PShop and it opens as a greyscale image.

Figured out the problem. The options for creating the PDF in PShop had "Include destination profile" checked. That makes it CMYK. Uncheck that option and it stays greyscale.

best, gordo

 

[prepress cindy]

thank you!!!!!
Yes I know this is not the best way to go about converting but I am not the one actually doing it.

 

[Greg_Firestone]

Hi Cindy,

Glad to hear you have a workaround. As an alternative solution for the person with Photoshop, they can use FixMyPrintFile to perform the conversion. It keeps keep the file object-based. There's a free trial when anyone signs up so they can essentially fix it for free.

Regards,
Greg

 

[Lukas Engqvist]

I find it easiest to use the colour converter built into Arobat. If you just need to change one image you can select it with the touch up tool and then choose "properties…" from the contextual flyout. In the "Color" tab you can assign or convert to ICC profile. Converting to a grey profile and NOT checking embed profile will convert to the grey profile but tagg it as Device Grey