Problem saving in 150dpi or 300dpi. Photoshop just saves every file on 72dpi.

Hi

There is a difference between saving and exporting which is not a bug but by design.

PPI is just metadata, stored alongside the image and is used by a print driver to calculate an actual physical size on paper from the pixels in the image and also by the Photoshop ruler when showing dimensions in inches or centimetres. Changing the ppi does not affect the image itself, just the size at which it will print out, quite literally how many pixels are used in every inch.

When saving, the ppi metadata is saved in the file alongside the image, provided the file is saved to a format that supports such metadata.

When exporting a file, no ppi metadata is saved in the file (the exception being save for web, but only when the metadata menu is set to save all metadata). This is because the export function was designed for saving for screen use, where ppi is meaningless. If you open a file with no ppi metadata, then Photoshop allocates 72ppi just so it has a number to work with. This doesn't affect the image itself.

So, in short, no bug - just Photoshop working as designed.

Dave

DPI is just a ratio between the pixels size of the image and the printing size

Image width : 1920 pixels

DPI : 300

You can print up to 1920÷300 : 6,4 inches width image

DPI : 150

You can print up to 1920÷150 : 12,8 inches width image

So when you export for web (or anything else) you save the image at the real pixels size (and can also downsize it BTW).

For instance this image is 1920 pixel width

If you uncheck resampling and downsize it to 150 DPI you will no longer see pixels units

Its size is now twice the original width in centimeters, but if you look at dimensions the width is still 1920 pixels as it was originally

So at the end of the day the DPI are not relevant as a measuring unit.

It is just a way to know what size to expect for a good quality printing.

What reallymatters is the pixels size.

@tierisw 

You may wish to take a look at the following topic, this has come up many times in the past:

https://community.adobe.com/t5/photoshop-ecosystem-discussions/why-does-photoshop-export-300-ppi-image-as-72-ppi/td-p/8676225

If you are using export the save files Export is designed for saving Web  image size assets.  Resolution is meaningless on the web because web Display devices can not change the display's device pixel size. Display have one resolution, the resolution they are manufactured with, only the number of Pixels the document canvas has is important on the web..  So export does not set any Print Resolution.  Resolution is a printer setting. The density to print pixels at.    If you Open a Image file that has no print resolution set.  Photoshop will default the document Print resolution to 72 PPI. You can change that before you print the image to print the image the size you want the print to have. Resolution is Pixels print size.

I found a link that may help you.

https://feedback-readonly.photoshop.com/conversations/photoshop/photoshop-only-exports-300-dpi-as-72-dpi/5f5f46214b561a3d427507e8