600dpi JPG printing issues

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Level 1

19 points

600dpi JPG printing issues

I'm working with a local print shop to print 5x7 blank photo note cards for sale at an upcoming studio tour. I reviewed the printer's proof cards today and was disappointed at how grainy the images were compared to the draft cards that I printed on my Canon injet printer.

The print shop uses a Xerox digital printer to print the cards. They requested at least 300 dpi images, but said 600dpi was even better. My Canon printer prints at 600dpi, so I used Preview to convert my JPEGs (exported full size from the Photos application) to 10x14 inch 600 dpi jpgs.

During our discussion it was mentioned that the Xerox printer they use converts JPGs to PDF in the printing process (he may have meant that the printer uses PostScript) and suggested that I provide my images as a PDF file.

When I convert a 600 dpi 10x14 image to PDF using the printer dialog I get a file that is the same size as my JPG, but the resolution in the get-info dialog is 720x1008, or 72 dpi.

Questions:

How can I convert the 600 dpi JPG to a 300 or 600 dpi PDF?

Is it possible that I'm getting visual artifacts in the printed cards because my 10"x14" 600dpi images are being resized to 5x7 images?

In the meantime, I'm going to ask the print shop to print proofs using 5x7 JPGs at 300 and 600 dpi as well PDF files of the JPGs and see if I get any better results.

Thanks for your help,

Mike

MacBook Pro 13", macOS 10.14

Posted on Mar 11, 2019 1:58 PM

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Answer 1

Mar 11, 2019 3:12 PM in response to mblotzer

I would just send them a 3000 x 4200 hi-quality (as little compression as possible) JPEG and let them worry about it.

A 3000 x 4200 .tif would be better.

Photos does not do dpi very well, because - as you found out- it is too easy to get twisted in your shorts.

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Answer 2

mblotzer Author

Level 1

19 points

Mar 14, 2019 11:17 AM in response to Keith Barkley

The print shop did a test print of one of my photos in various formats: JPEG at 72, 300, and 600 dpi; TIFF at 72 and 300 dpi; and copies of the files saved to PDF from the Mac's print dialog. The only noticeable difference in the prints was that the color of the TIFF versions was a slightly better match to the photo printed on my Canon 8100 printer.

My main conclusion is that dpi density makes no difference when printed by a PostScript printer. (Which makes sense to me. But why do the print shops and online printing services all ask for a minimum 300 dpi?)

The prints are fine for many of my photos. But for the photos that I want buttery smooth bokeh, I'll need to find another printer or make the note cards myself using my Canon inkjet printer.

Mike

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Answer 3

Mar 12, 2019 8:38 AM in response to mblotzer

Actually, you should just send them all the pixels you have, i.e., the size of the original minus any cropping.

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Answer 4

mblotzer Author

Level 1

19 points

Mar 12, 2019 6:15 AM in response to Keith Barkley

Thanks, I've included TIFF versions of the photo for test printing by the printer. Looking forward to the results...

Mike

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Answer 5

Mar 14, 2019 1:24 PM in response to mblotzer

"But why do the print shops and online printing services all ask for a minimum 300 dpi?"

Because that is what they know, and what they have to do to ensure a good print.

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600dpi JPG printing issues

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