How do I write a matrix as a raw bitmap in R - r

Question

Not the problem:
There are lots of folks who ask variations on "how do I save a figure" where the figure has borders, annotations, and style; I'm not looking for any of that because I can do it in base, lattice, or ggsave. If you need me to, then I can make a list of 20 SO questions this isn't the same as.
tl;dr
I want to have a bitmap file where my matrix is the values. In python, using OpenCV I can read a matrix, and the pixel [1,1] is going to have a particular value. If I change it, and save it, then that intensity value has changed. How do I get that?
Details:
When I run this code:
set.seed(1)
img_data <- matrix(sample(x = 0:255, size = 228*228,replace = T),nrow = 228,ncol = 228)
image(img_data)
I get this image:
You can see the default annotation. Annotation can be removed.
set.seed(1)
img_data <- matrix(sample(x = 0:255, size = 228*228,replace = T),nrow = 228,ncol = 228)
image(img_data, xaxt='n',yaxt='n')
And this looks less bad.
but opened in mspaint, it shows the problem.
Problems:
White border around actual information
image size is 789x503
I want an image that is 228x228, and the value [1,1] of the image is value [1,1] of the matrix.
How in base, lattice, ggplot, or something else R, does one make that?
Update:
This almost works.
set.seed(1)
img_data <- matrix(sample(x = 0:255, size = 228*228,replace = T),nrow = 228,ncol = 228)
mar_old <- par("mar") #lets not permanently change values
xpd_old <- par("xpd") #lets not permanently change values
bmp(filename = "mytest.bmp", width = 227, height = 228, units = "px")
par(mar=rep(0, 4), xpd = NA)
image(img_data, bty ="n",axes=F,frame.plot=F, xaxt='n', ann=FALSE, yaxt='n', asp=1)
dev.off()
par(mar=mar_old, xpd=xpd_old)
It makes this image
It still leaves a white line on the right and lower edges when viewed in mspaint.
Perhaps bitmaps start their counting at zero??
Update2:
This almost works, and might be what I have to go with.
library(magick)
set.seed(1)
img_data <- array(sample(x = 0:255, size = 228*228*3,replace = T),dim = c(228,228,3))
img <- magick::image_read(img_data/255)
image_write(img, path = "mystes3.bmp", format = "bmp")
It gives this:
And in mspaint:
It has to have 3 layers, RGB (rgba?), to get converted. This means it is a 3d array and not a 2d matrix. It gets the size right in that it doesn't add padding.

Answer 1

You need to set the useRaster parameter to TRUE in image():
set.seed(1)
img_data <- matrix(sample(x = 0:255, size = 228*228,replace = T),nrow = 228,ncol = 228)
mar_old <- par("mar") #lets not permanently change values
xpd_old <- par("xpd") #lets not permanently change values
bmp(filename = "mytest.bmp", width = 228, height = 228, units = "px")
par(mar=rep(0, 4), xpd = NA)
image(img_data, bty ="n",axes=F,frame.plot=F, xaxt='n', ann=FALSE, yaxt='n', asp=1, useRaster = T)
dev.off()
par(mar=mar_old, xpd=xpd_old)
I also corrected the height to 228 instead of 227.
Did a smaller image:
With useRaster = T
Without useRaster:
Without useRaster you even lose a row and a column.