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rstringmatrixgrayscale

Obtain rendered grayscale image of text as a matrix

I want to render a given string as a grayscale image and subsequently perform some simple manipulations on it. I am aware of the text() function. Unfortunately this requires opening a graphical device. For my purpose it would be a lot more convenient and efficient to directly store the grayscale image in a matrix instead.

What is an efficient way of obtaining a matrix representation of the rendered grayscale image of a given string?

Solution

  • The magick package as suggested by Richard Telford was key to solving the question:

    # 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]]))