To see how big or at what resolution your picture is, do the following:
- Open the image in Photoshop.
- Select Image>Image Size
To change the resolution of the image, do the following:
- Deselect (uncheck) the Resample Image check box (this will also deselect Constrain Proportions).
- Change the Resolution. This will automatically change the Width & Height.
To change the size of the image, do the following:
- Be sure that Resample Image and Constrain Proportions are checked.
- Change either the Width or Height measurement. This will automatically change the other measurement to keep the image in proportion.