Resolution. "Real-world" image resolution, typically expressed as pixels per inch, but may also be in other units, such as pixels per meter.
Real number, larger than 0. Required for texture and decal materials, unless the image resolution is the same as attribute::Resolution. Ignored by solid color and cabinet materials.
attribute::Resolution is used if the field is not present, if the value is 0 or negative, or if the field is empty.