Because printing an entire book in color is more expensive, I am trying to deliver greyscale PDFs to the printer, without success:
- I convert image to greyscale in Paint.net or Photoshop Elements. Save image as JPEG. (I also tried IrfanView.)
- Mount the image on a page in Scribus.
- Export as PDF from Scribus.
Test ink coverage with Ghostscript. For a file where the First page contains an image, and the second page does not, this results in something like:
c:\>C:\"Program Files"\gs\gs9.27\bin\gswin64c.exe -q -o - -sDEVICE=inkcov Bwtest.pdf 0.09917 0.09917 0.09917 0.10612 CMYK OK 0.00000 0.00000 0.00000 0.05997 CMYK OK
The color channels are still there, thus making it a color image although it appears as greyscale. How do I make an image true greyscale without color channels? Can the JPEG format even contain an image with only greyscale, or should I use some other format?