resolution showing in px per inch and not px per cm in action item

i am all confused on the options to select in recording & saving an action with different results...

if i do this manually (one file at a time) in setting the resolution with 72 px per cm, i will get the resolution with 72 px per cm on my jpg file with no problem ... the issue happened if i recorded as action and run a batch of files to save time ... this is why i do not understand and confused ... do i have to do it one file at a time in order to avoid this issue? ... it will take me months to finish all the files....

cheers,

I first set my ruler units to CM, then recorded changing the PPCM value without resampling:

However if you then go into prefs and change the ruler units to Inches, you can see the PPCM value in the action panel dynamically change to reflect the new ruler units of PPI.

I saved the action file and then used xtools to convert the action to both a .jsx and .xml file and the actual resolution was reported as 304.800003051758 ppi – which lines up with D Fosse’s statement in post #3.

So it looks to be just how things work, just as points is the internal unit used for PDF, independent of whether one uses inches or metric.

why photoshop provided the options to pick and its internal calculations are ppi only? ... why give users option? ... is it something strange? why not just have ONLY unit measurement in inch ... NO OPTION? ... why?...

I'd recommend using pixels per inch even if you're in a "metric" country (like me). It's the universal standard used everywhere, and introducing pixels per cm will most likely just cause confusion.