Have you tried using Image size with resample NOT check set 300 DPI print resolution click OK. The number of pixels will not change if yoy do not resample. Record an action set 300 dpi.
Just normal rounding. Ppi isn’t exact in PNG because it’s metric. Try not to worry.
Good advice from Test Screen Name.
PNG can only store resolution in dots per meter (dpm)
It's an Imperial (dpi) to metric (dpm) conversion that takes place. PNG format resolution is captured as dots per meter. When dpi is converted to dpm floating point math is done by Photoshop. This is not 100% accurate.
300 dpi is approx 11811 dpm
11811 dpm translates299.9994 dpi
You can try this yourself at Convert dot/meter [dot/m] <—> dot/inch [dpi] • Photometry — Light • Digital Image Resolution • Compact Calculator
There is a minuscule difference between 300 and 299.99 dpi. Practically indiscernible.
Don't lose sleep over it.
Yes, i did try to uncheck the resample, did not help.
this issue happen suddenly and my guess is that something what wrong with photoshop. i read that scripting may be changed
My problem is that i post my work to a service that reject anything that is not 300 ppi.
Thank you, i already read all about the ppi dpi metric inches conversion but the thing is that a week ago i did not have any problem saving PNG with 300 ppi and now i have a problem.
somehow Photoshop is messed up and i don't know how to correct it
Have you actually tried your service?
No, nothing is messed up. I asked, did you actually try your service (that supposedly will reject your PNG)?
Quite honestly this makes little sense and these people can't know what they're asking for. What they should be asking for is minimum pixel dimensions. That's the only meaningful parameter.
That a print has to be 300 ppi is just a myth, maintained by people who don't know what it means. 300 ppi is a theoretical upper limit for offset print, beyond which no improvement is technically possible (if printed with a standard 150LPI screen). But that doesn't mean you can see any difference between 300 and 290.
It doesn't apply for inkjet. Each inkjet printer has its own optimal resolution - in Epson it's usually 360 ppi.
Anyway - PNG being metric means they will probably never get a PNG that is exactly 300.