ふーん・なるほどね

Current spec is here. Please update doc.

height: provided, width: not provided
using height
height: not provided, width: provided
using width
height: not provided, width: not provided
using original image height and width
height: provided, width: provided
If original image height > original image width then
If original image height > height then
using height
Else original image width > width then
using width
Else ( original image width == width ) AND ( original image height == height ) then
using original image height and width
Else ( original image height width then
using width
Else original image height > height then
using height
Elese original image width == width && original image height == height then
using original image height and width