获取呈现的文本的灰度图像作为矩阵

Question

我想呈现给定的字符串作为灰度图像，随后对其执行一些简单的操作。我知道text()函数。不幸的是，这需要打开图形设备。为了我的目的，将灰度图像直接存储在矩阵中会更加方便和高效。

获得给定字符串渲染灰度图像矩阵表示的有效方法是什么？

Answer 1

的magick包为理查德·德福建议是关键，解决这个问题：

# Load the package 
require(magick) 

# Create white canvas initializing magick graphical device 
img <- image_graph(width = 140, height = 40, bg = "white", pointsize = 20, 
        res = 120, clip = TRUE, antialias = TRUE) 
# Set margins to 0 
par(mar = c(0,0,0,0)) 

# Initialize plot & print text 
plot(c(0,1), axes = FALSE, main = "", xlab = "", ylab = "", col = "white") 
text(0.95, 0.42, "Test", pos = 4, family = "mono", font = 2) 

# Close the magick image device 
dev.off() 

# Convert to grayscale & extract pixelmatrix as integers 
img <- image_convert(img, colorspace = "gray") 
target <- drop(as.integer(img[[1]]))