## ----fig.width=7, fig.height = 4.7,echo=FALSE---------------------------------
library(png)
library(grid)
img <- readPNG("./img/figure_MTA1.png")
grid.raster(img)

## ----fig.width=7, fig.height = 4.8,echo=FALSE---------------------------------
img <- readPNG("./img/figure_MTA2.png")
grid.raster(img)

## ----fig.width=7, fig.height = 6,echo=FALSE-----------------------------------
img <- readPNG("./img/figure_MTA3.png")
grid.raster(img)