Exporting to PNG as CMYK

Many professional Printer drivers have both CMYK and RGB portions of their drivers. Epson is one that comes to mind.  Rips take advantage of Postscript and convert that to CMYK or RGB but mainly rasterize the vector art.   

Only printers driven by RIP software can take CMYK right through the process. The "normal" inkjet printer driver software uses the "Quickdraw pipeline" so it's purely RGB based.

IF you send a CMYK file through that process it is first converted to RGB then the driver works out how to use the multiple inks to print it. So making CMYK in this instance is a mistake.

As others have written, forget EXPORT its for web use. 

Use "save as" and make sure you check "embed profile" 

It can be preferable to send out images in the sRGB colour space to users who may know little about colourmanagement, it's safer. But if your originals are in a larger colour space, such as Adobe RGB* then save (archive) the Adobe RGB original as TIF or PSD and make a copy - convert this to sRGB, resize***, save as a JPEG** and send out to your customer. 

(*Adobe RGB is a larger volume colour space, so capable of "containing" more saturated colours)

(**Forget PNG, Jpeg is a standard compressed format for print files.)

(***I'd decide on a print size - say it's A4 and resize the image to 300ppi at A4.

(or 240 or 360 ppi [edited] if its for an Epson printer only))

72ppi is only suitable for a file to be used onscreen - it's a display screen resolution.

Read about ICC profiles and colour spaces here: 

here is some reading on ICC profiles and how they work for you to provide accurate colour through the digital workflow: https://www.colourmanagement.net/advice/about-icc-colour-profiles/

I hope this helps

if so, please "like" my reply

thanks

neil barstow, colourmanagement.net :: adobe forum volunteer

[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 the thread title and the chronological order]

And to reiterate: When providing RGB images they should have their profiles embedded. 

Hi

You have some basics to learn.

1. 1. There is no generic CMYK. There are specific CMYK profiles based on the output press. It is important to use the right one.  Converting between CMYK profiles is not a good idea. Note I said output press. If the output is to be inkjet then the document should be RGB. Inkjet drivers expect RGB data.

2. Export functions are designed for Web use. As such they strip out the PPI value, which is just that - a number held in the file. The purpose of that number is to tell a print driver how many image pixels to print in a given area and hence how big the physical print will be. For web use, displayed on a screen, that PPI value is irrelevant and is removed. When you open a document with no PPI value, Photoshop assigns 72 PPI as a default. This is only do it can show you a print size. So the change you saw from 300 PPI to 72 PPI was caused by export removing the irrelevant PPI value altogether. As you correctly say the image pixels are unchanged.

3. PNG may or may not be the best format. For graphics, it can work well and it does support transparency. For photographic images, with no transparency, jpeg is a better format and usually results in smaller file sizes.

Dave

I agree that CMYK is certainly the wrong thing for something sold for printing by ordinary customers. If you were making it for a print shop, with a known CMYK press and inks, it might be practical. But the really big thing here - and someone has mentioned it but you may not have picked this up - you cannot save a CMYK PNG file, because there is NO SUCH THING. 

I concur with Mr. Pfaffenbichler. Exporting to CMYK is useless. Such a workflow would mandate proper color management, calibrated monitors, profiled printers - none of which is relevant or known to average customers. All they may want is to print your graphics on their home printer using its default settings, which will simply assume standardized sRGB data funneled your operating system's print engine. The same applies to the resolutions stuff als already explained. Should professional commercial printers want to license and use your work, I'm sure they'll contact you and request editable source files for the right price, so no point to bother with convoluted procedures for now.

Mylenium

Providing fine data as png is not a proper choice, also as it does not support CMYK. 

And why would you provide CMYK images in the first place? Are you sure you know the actual print conditions? 

You seem to get hung up on an irrelevant factor here – the resolution is not relevant if you cannot be absolutely sure about the final print size; what matters are the pixel dimensions. Will they provide for a sufficient resolution at plausible output sizes? 

8x10 inches at 300ppi or 33,333x41,667 inches at 72ppi does not really make the image better or worse. 

And why do you not export a pixel image from Illustrator straight away?