PNG file - RGB vs CMYK

[simonep87641696]

I have a portifolio to print. I found out all images are in good resolution (300Actual PPI). However most images are on RGB mode.

I had open the file as PNG on Photoshop and Illustrator. Both programs allow me to swap the colour mode from RGB to CMYK. The problem is when I save the file, it only allows me to save as PSD or AI. I do not have PNG option to save the new CMYK file. So I had saved in both files, PSD and AI. Then if I try to convert it as PNG, the colour mode goes back to RGB colour mode again.

This is driving me crazy... Or it is something very simple that I'm not thinking, or PNG can't be CMYK? Could anyone please help me 🙂

[Nancy OShea]

1. Open image in Photoshop.
2. Go to Edit > Image Mode and select CMYK.
3. File > SaveAs PDF with a high quality print preset.  Ask your print professional which preset they want you to use.

[simonep87641696]

Thank you so much Nancy... I'm such a beginner.

I remember my teacher saying: if you are going to print PNG are better files and resolution has to be 300 etc. So if I save on PDF, does it keep its resolution (on this present you said)? Does it keep transparencies?

[Nancy OShea]

PNG transparency is used on the web.  It has no relevance in printed material where subject and background occupy different layers in native Photoshop files.  

It sounds like you've created graphics for online viewing but now you want to print them?  Ideally, you create your printed artwork first and save to layered PSD files.  Then you export to JPG or PNG and optimize for online viewing.  So you should always have at least 2 file types, native PSDs and optimized JPG or PNGs for web.

I opened a PNG icon and SavedAs PDF with the following settings.

Give it a try.

[simonep87641696]

Thanks again Nancy. I will do it...

the files were created during my course. I am trying to put them together to be printed. Thanks again. Cheers

[PECourtejoie]

Hello, how will the files be printed? You need to convert to CYMK for press printing, NOT for digital, laser, or inkjet printing.

[simonep87641696]

Yes you are right... there is a very good answer for me bellow. Thanks for your reply

[NB, colourmanagement net · Accepted solution]

Hi,

1: PNG

I can see no reason whatsoever to choose PNG for printing images. I think it’s a bad idea.

Wikipedia agrees

"The PNG working group designed the format for transferring images on the Internet, not for professional-quality print graphics"

see: Portable Network Graphics

TIFF or flattened (no layers) PSD would be better, if you are confident on size JPEG is OK too, but not my favoured file type since it compresses data and can damage appearance if subsequently croped or resized (and, if saved as JPEG again, inevitably, recompressed).

PDF is OK for print, but its more for documents with text and graphics than simple image files.

2: CMYK? why? and what CMYK?

For general inkjet and some laser prints (printers without RIP software) RGB is the better colour format.

For offset press, digital press, some laser printers, Inkjet with RIP etc, CMYK image type is needed, BUT you should never simply use image / mode CMYK to achieve this without consdieration, since that defaults the important RGB to CMYK conversion to whatever CMYK ICC profile has been chosen in color settings.

CMYK (just like RGB) needs the right ICC profile to properly describe the colour and relate it to visual appearance. Think of it as a language, your RGB data can be translated to CMYK but first we need to know more about the "language" the printing device understands.

A CMYK ICC profile contains the "language" information needed to give correct colour balance for a specific printing condition, (machine, ink, paper).

In the profile, each required original colour has an ink recipe calculated to provide accurate colour and tone (within device capability) on a specific device type with specific ink and paper.

If a printing service just asks for "CMYK" you need to know "what CMYK" i.e what CMYK ICC profile to use (in the conversion from RGB to CMYK) - if they can't tell you its best to use another printing service.

To hit the colour dartboard you have to know where to aim the dart.

Guessing on ICC profiles for CMYK conversions or simply using whatever ICC profile happens to be set in color settings (in many cases that may be the default of SWOP) is the road to disappointment with printed image colour rendition, unless, by some coincidence, that’s just what your printer wants.. 

I hope this helps

if so, please "like" my reply and if you're OK now, please mark it as "correct", so that others who have similar issues can see the solution

thanks

neil barstow, colourmanagement.net

[please do not use the reply button on a message in the thread, only use the one at the top of the page, to maintain chronological order]

[Test Screen Name]

You are correct, by the way, that PNG is RGB only. No need for CMYK support in a graphic meant only for web use. So this limitation comes from PNG’s design, not Adobe’s software. 

[simonep87641696]

Thanks Neil and thanks everyone. The answers I've got helped a lot. Cheers