从字符数组中生成基于像素的图像R

Question

我有一个非常长的字符数组。我想通过将每个字符编码为图像中的某种颜色来生成基于像素的图像（光栅图像）。例如，'A'为红色像素，'B'为紫色，...和'Z'为其他颜色。我正在使用R。

请帮我我如何生成这样的基于像素的图像。我在R中搜索并找到了光栅和像素图包，但我是R新手，不确定如何将它们用于我的情况。任何帮助表示赞赏。由于

Answer 1

这里是一个可能的解决方案：

library(png) 
library(tiff) 
library(abind) 

# function which plots the image 
createImage <- function(txt,charToColorMap,destinationFile,format=c('png','tiff'),debugPlot=FALSE){ 

    # helper function which finds all the divisors of a number 
    divisors <- function(x){ 
    y <- seq_len(x) 
    y[ x%%y == 0 ] 
    } 

    # split the string in charaters 
    chars <- strsplit(txt,'')[[1]] 

    # find the most "squared" rectangle that contains all the characters without padding 
    d <- divisors(length(chars)) 
    y <- d[length(d) %/% 2] 
    x <- length(chars)/y 

    # create an array with 4 matrices (or planes) one for each RGBA channel 
    RGBAmx <- col2rgb(charToColorMap,alpha=TRUE)/255 
    colorIndexes <- match(chars,names(charToColorMap)) 

    colorIndexesR <- matrix(RGBAmx['red',colorIndexes],nrow=y,ncol=x,byrow = TRUE) 
    colorIndexesG <- matrix(RGBAmx['green',colorIndexes],nrow=y,ncol=x,byrow = TRUE) 
    colorIndexesB <- matrix(RGBAmx['blue',colorIndexes],nrow=y,ncol=x,byrow = TRUE) 
    colorIndexesA <- matrix(RGBAmx['alpha',colorIndexes],nrow=y,ncol=x,byrow = TRUE) 

    planes <- abind(colorIndexesR,colorIndexesG,colorIndexesB,colorIndexesA,along=3) 

    # write the PNG image 
    if(format[1] == 'png'){ 
    writePNG(planes,destinationFile) 
    }else if(format[1] == 'tiff'){ 
    writeTIFF(planes,destinationFile) 
    }else{ 
    stop('usupported format') 
    } 

    # for debug purpose only we plot the image... 
    if(debugPlot){ 
    mx <- matrix(colorIndexes,nrow=y,ncol=x,byrow = TRUE) 
    image(z=t(mx[nrow(mx):1,]),col=charToColorMap) 
    } 

    invisible() 
} 

用法：

# arbitrary and incomplete LETTER -> COLOR map 
charToColorMap <- c(A='red',B='blue',C='green',D='black',E='yellow',F='orange') 

txt <- "ABACDAAFFEDDADFAFAED" 

createImage(txt,charToColorMap,destinationFile = "test.png",debugPlot=TRUE) 

得到的PNG图像（800％缩放看到像素）：