使用以下代码行：
##from http://abcnews.go.com/images/International/homocides_g8_countries_640x360_wmain.jpg
knitr::include_graphics("R/img/homocides_g8_countries_640x360_wmain.jpg")
我得到的不是我期望的图像：
[1] "R/img/homocides_g8_countries_640x360_wmain.jpg"
attr(,"class")
[1] "knit_image_paths" "knit_asis"
为什么会这样？