rasterImage adjusting to zero distortion

Description

Call rasterImage to plot image from (xleft, ybottom) to either xright or ytop, shrinking one toward the center to avoid distortion.

angle specifies a rotation around the midpoint ((xleft+xright)/2, (ybottom+ytop)/2). This is different from rasterImage, which rotates around (xleft, ybottom).

NOTE: The code may change in the future. The visual image with rotation looks a little off in the examples below, but the code seems correct. If you find an example where this is obviously off, please report to the maintainer – especially if you find a fix for this.

Usage

rasterImageAdj(image, xleft=par('usr')[1], ybottom=par('usr')[3],
     xright=par('usr')[2], ytop=par('usr')[4], angle = 0,
     interpolate = TRUE, xsub=NULL, ysub=NULL, ...)

Arguments

Details

1. imagePixels = number of (x, y) pixels in image. Do this using dim(as.raster(image))[2:1], because the first dimension of image can be either x or y depending on class(image). For example link[EBImage]{Image} returns dim with x first then y and an optional third dimension for color. A simple 3-dimensional array is assumed by rasterImage to have the y dimension first. as.raster puts all these in a standard format with y first, then x.

2. imageUnits <- c(x=xright-xleft, ytop-ybottom)

3. xyinches = (x, y) units per inch in the current plot, obtained from xyinch.

4. Compute pixel density (pixels per inch) in both x and y dimension: pixelsPerInch <- imagePixels * xyinches / imageUnits.

5. Compute imageUnitsAdj solving 4 for imageUnits and replacing pixelsPerInch by the max pixel density: imageUnitsAdj <- imagePixels * xyinches / max(pixelsPerInch).

6. (dX, dY) = imageUnitsAdj/2 = half of the (width, height) in plotting units.

7. cntr = (xleft, ybottom) + (dX, dY).

xleft0 = cntr[1]+sin((angle-90)*pi/180)*dX*sqrt(2); ybottom0= cntr[2]-cos((angle-90)*pi/180)*dY*sqrt(2);

(xright0, ytop0) = (upper right without rotation about lower left) xright0 = xleft0+imageUnitsAdj[2] ytop0 = ybottom0+imageUnitsAdj[2]

8. rasterImage(image, xleft0, ybottom0, xright0, ytop0, angle, interpolate, ...)

Value

a named vector giving the values of xleft, ybottom, xright, and ytop passed to rasterImage. (rasterImage returns NULL, at least for some inputs.) This shows the adjustment, shrinking toward the center and rotating as desired.

Author(s)

Spencer Graves

See Also

rasterImage

Examples

# something to plot 
logo.jpg <- paste(R.home(), "doc", "html", "logo.jpg",
                  sep = .Platform$file.sep)
if(require(jpeg)){
##
## 1.  Shrink as required
##
  Rlogo <- readJPEG(logo.jpg)
  
  all.equal(dim(Rlogo), c(76, 100, 3))
  

  plot(1:2)
# default
  rasterImageAdj(Rlogo)

  plot(1:2, type='n', asp=0.75)
# Tall and thin
  rasterImage(Rlogo, 1, 1, 1.2, 2)
# Fix
  rasterImageAdj(Rlogo, 1.2, 1, 1.4, 2)

# short and wide
  rasterImage(Rlogo, 1.4, 1, 2, 1.2)
# Fix
  rasterImage(Rlogo, 1.4, 1.2, 2, 1.4)
##
## 2.  rotate 
##
#  2.1.  angle=90:  rasterImage left of rasterImageAdj
  plot(0:1, 0:1, type='n', asp=1)
  rasterImageAdj(Rlogo, .5, .5, 1, 1, 90)
  rasterImage(Rlogo, .5, .5, 1, 1, 90)
#  2.2.  angle=180:  rasterImage left and below 
  plot(0:1, 0:1, type='n', asp=1)
  rasterImageAdj(Rlogo, .5, .5, 1, 1, 180)
  rasterImage(Rlogo, .5, .5, 1, 1, 180)
#  2.3.  angle=270:  rasterImage below 
  plot(0:1, 0:1, type='n', asp=1)
  rasterImageAdj(Rlogo, .5, .5, 1, 1, 270)
  rasterImage(Rlogo, .5, .5, 1, 1, 270)
## 
## 3.  subset 
##
dim(Rlogo)
# 76 100 3
Rraster <- as.raster(Rlogo)
dim(Rraster)
# 76 100:  
# x=1:100, left to right 
# y=1:76, top to bottom 
rasterImageAdj(Rlogo, 0, 0, .5, .5, xsub=40:94)
}

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(Ecfun)

Attaching package: 'Ecfun'

The following object is masked from 'package:base':

    sign

> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/Ecfun/rasterImageAdj.Rd_%03d_medium.png", width=480, height=480)
> ### Name: rasterImageAdj
> ### Title: rasterImage adjusting to zero distortion
> ### Aliases: rasterImageAdj
> ### Keywords: hplot
> 
> ### ** Examples
> 
> # something to plot 
> logo.jpg <- paste(R.home(), "doc", "html", "logo.jpg",
+                   sep = .Platform$file.sep)
> if(require(jpeg)){
+ ##
+ ## 1.  Shrink as required
+ ##
+   Rlogo <- readJPEG(logo.jpg)
+   ## Don't show: 
+ stopifnot(
+ ## End(Don't show)
+   all.equal(dim(Rlogo), c(76, 100, 3))
+   ## Don't show: 
+ )
+ ## End(Don't show)
+ 
+   plot(1:2)
+ # default
+   rasterImageAdj(Rlogo)
+ 
+   plot(1:2, type='n', asp=0.75)
+ # Tall and thin
+   rasterImage(Rlogo, 1, 1, 1.2, 2)
+ # Fix
+   rasterImageAdj(Rlogo, 1.2, 1, 1.4, 2)
+ 
+ # short and wide
+   rasterImage(Rlogo, 1.4, 1, 2, 1.2)
+ # Fix
+   rasterImage(Rlogo, 1.4, 1.2, 2, 1.4)
+ ##
+ ## 2.  rotate 
+ ##
+ #  2.1.  angle=90:  rasterImage left of rasterImageAdj
+   plot(0:1, 0:1, type='n', asp=1)
+   rasterImageAdj(Rlogo, .5, .5, 1, 1, 90)
+   rasterImage(Rlogo, .5, .5, 1, 1, 90)
+ #  2.2.  angle=180:  rasterImage left and below 
+   plot(0:1, 0:1, type='n', asp=1)
+   rasterImageAdj(Rlogo, .5, .5, 1, 1, 180)
+   rasterImage(Rlogo, .5, .5, 1, 1, 180)
+ #  2.3.  angle=270:  rasterImage below 
+   plot(0:1, 0:1, type='n', asp=1)
+   rasterImageAdj(Rlogo, .5, .5, 1, 1, 270)
+   rasterImage(Rlogo, .5, .5, 1, 1, 270)
+ ## 
+ ## 3.  subset 
+ ##
+ dim(Rlogo)
+ # 76 100 3
+ Rraster <- as.raster(Rlogo)
+ dim(Rraster)
+ # 76 100:  
+ # x=1:100, left to right 
+ # y=1:76, top to bottom 
+ rasterImageAdj(Rlogo, 0, 0, .5, .5, xsub=40:94)
+ }
Loading required package: jpeg
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>