Here's how you can turn a colorful image to a black & white image for offset printing where you'll need only pure BLACK channel to make a plate for printing.
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Watch video How to convert 4-color image to Black (CMYK) | Channel Mixer in Photoshop online, duration hours minute second in high quality that is uploaded to the channel My Silly Channel 21 May 2018. Share the link to the video on social media so that your subscribers and friends will also watch this video. This video clip has been viewed 17,927 times and liked it 193 visitors.