prince-image-resolution: dpi | normal | auto [ , normal | dpi ]?
This property determines the resolution of an image. The value normal means 96dpi, or else the current CSS DPI setting. A custom DPI value can also be specified. The value auto means to check the original resolution of the image. One can specify a second value, as for example auto, normal or auto, 300dpi in order to check the original resolution of the image first, and to fall back on the second value if the image doesn't contain resolution information.
Note that image-resolution can be used as a shorthand for this property.