Exporting to PNG as CMYK

[jughead77a]

I have been trying to save my images to print so I can sell them on my Etsy shop.

First I copy and paste from Illustrator into Photoshop onto the canvas (8x10 inches / 2400x3000 pixels at 300ppi) as a vector smart object. Then I flatten or merge all the layers then go to Layer > Export as > PNG.

After I saved it I open the document again. I check the ppi which is now at 72ppi and the inches have changed to 33 x 41 inches but the pixels remain the same!! wtf?

This is so confusing to me. Can someone tell me what I'm doing wrong?

[davescm]

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

Just for clarity ( I realise you know this Neil but for other users reading through the thread), the document ppi is irrelevant for screen use. It is used for calculating the size the document will print.. What matters for on screen use is the dimensions in pixels - that is it.

One place the display screen resolution can be entered is in Photoshop's preferences, where it is used along with the document ppi to calculate the on screen size when using "View >Print Size", but in reality there are few screens these days which only have 72ppi. Most are higher and some much higher.

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

(or 240 or 260 ppi if its for an Epson printer only))

The Epson drivers do not scale at 360 ppi - so if you want to control the scaling algorithm in Photoshop and avoid the driver scaling then use 360 ppi (or 720 ppi) on Epsons. You can prove this through testing, as I have done with test patterns on my Epsons, although with real world images you would be hard pressed to see a difference.

Dave

[NB, colourmanagement]

Dave,

You're right - thanks for explaining further about screen rez. Mine was oversimplified. 

Also for spotting my Epson printer ideal resolution typo error, I meant 240 or 360 (not 260!)

I did some rather extensive testing with tech head Joseph Holmes https://www.josephholmes.com many years ago which settled the argument for me about Epson driver scaling once and for all, you're right that an integer of the native resolution: 720 is superior

SO - 360, 240 and even 180 gave far sharper thin lines than 300ppi

I love Joseph's work on ICC working space profiles: https://www.josephholmes.com/profiles/about-my-profiles - so enabling once grasped

Neil B

[Bob_Hallam]

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.   

Even printers with both CMYK and RGB in their drivers are subject to how any software sends files.  For example, Acrobat by default will send as RGB to Epson and not use the CMYK side of The Epson Driver 

To test which one you have, make two patches in the same image. One 100% CMY the next 100% CMYK 

If they both print black you probably have an RGB driver

Bob

[NB, colourmanagement]

Hi Bob,

Just to be clear, the OP is looking for advice on format for selling images online to the general public to print at home.

I don't think that sending CMYK files is relevant for him. 

I personally have never seen and Epson driver that will print, say 50%K with just black ink. 

thanks

neil barstow, colourmanagement.net :: adobe forum volunteer