Script for color space conversion RGB to CMYK - URGENT Help Wanted

[Adareimages2]

Excuse my ignorance with the basic nature of this question, I don't use InDesign, but I do have a pressing problem regarding it.

My book publisher has just emailed to say that my photography book has been set for the printers in InDesign and the photographs have AdobeRGB color space (which was what I was aksed to send.) The printer needs the images to be in CMYK. The publisher said that he was "pretty sure Adobe Acrobat converts the InDesign files to CMYK" and that he has sent the printer RGB images in the past and they "came out OK". He said that if this will not work, he needs to convert all of the images separately to CMYK.

Can you help with the following:

1. Is he right about the above - can Adobe Acrobat convert the files?

2. Can anyone offer me a script that will convert all of the images in InDesign to CMYK? or will he need to change them individually?

Thanks for any suggestions with this urgent request.

Stephen

[Harbs.]

1. Acrobat can convert.

2. No need for a script, if the printer needs CMYK, you can export a CMYK pdf.

3. To get the highest quality conversions, you might want to do it in Photoshop.

4. If the images are color managed and the printer has a modern work-flow a color managed RGB PDFX-4 pdf is probably the best way to go...

Harbs

[Adareimages2]

Harbs, thank you very much for the information, which I am sure will come a s great relief to my publisher. I have emailed it on to him.

Best wishes,

Stephen

[LeoMari-eL6mBl]

app.activeDocument.colors.everyItem().properties = {space:ColorSpace.CMYK};

Hug.

[Gavin Anderson]

For any who don't know how to write their own scripts, here is LeoMari's script in a form that you can drop directly into your InDesign Scripts folder.

Dropbox - RGB-2-CMYK.jsx

[Laubender]

Hi Gavin,

if you are using vector objects with RGB fills where you are using tints of RGB colors from your Swatches panel and convert from CMYK to RGB using the UI or Leo's script the result will be wrong separated CMYK colors as compared to an exported PDF/X-1a.

See the screenshot below where I used 4 rectangular shapes with RGB fills.
All should separate to the same CMYK value. But this will not happen.

Especially compare row 1 with row 3.

Row 1: RGB fill with different tints separated with Leo's script to CMYK before PDF export.
Row 2: RGB fill, no different tints, but reduced opacity not separated to CMYK before PDF export.

Row 3: RGB fill with different tints not separated to CMYK before PDF export.

Row 4: Placed PhotoShop image with layers of RGB fill set to different opacity values.

Separation results with Row 1 and 2 will be different from row 3 and 4.

In my opinion separation should follow the image that is placed. Row 1 and 2 will not.

FWIW: Leo's script is not the answer to the OP's question here.
It would not convert placed RGB pixel images to CMYK.

Regards,
Uwe

[Gavin Anderson]

Good point, and thanks.

Back to the drawing board.

[JessJoy]

A fast way to convert your images in InDesign from RGB to CMYK is to run through an automated Batch process using Photoshop. I have an action created to change the color from RGB and CMYK. You can call on the action in the Batch menu and then run your entire image folder at once. All you have to worry about in InDesign is updating the links at that point.

[Gavin Anderson]

For me, LeoMari​'s script accomplished what I needed. I didn't have any RGB images in the file supplied by our Marketing Dept, but they had created a lot (1,000's) of fills in RGB warm grays. None of them were actually swatches, just eyedropper readings of the surrounding image. I just needed to get them over to a close CMYK approximate, so they weren't tripping of 1'000's of preflight warnings.

So, my issue wasn't the same as the OP.