I'm working on a product packing design, so I need to have a barcode on the packaging. But when I attached the barcode PNG in Illustrator and exported the file to PDF format to print. The barcode turns out Gray color! I tried to "Unembed" the PNG and export it to PDF again; the barcode turns out normal. I don't understand why this is happening, and I'm not sure if it's ok that I do not embed the PNG and just send the file to the printer. So, questions: When I print the PDF file, will the "Unembed" PNG barcode still turns out normal?