Get pixel array of a Char

General Usage
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1

I am doing image processing work where I need to be able to manipulate images as arrays. I would like to make an array with values 0 or 1 such that the 1’s make the shape of a given letter. It is proving surprisingly difficult to find an elegant way to do this.

An example of what I would like:

function makeLetter(c::Char,nPixels::Int)
    # code....
end

makeLetter('o',10) 

 0  0  0  0  0  0  0  0  0  0
 0  0  0  0  0  0  0  0  0  0
 0  0  0  1  1  1  1  0  0  0
 0  0  1  1  0  0  1  1  0  0
 0  0  1  1  0  0  1  1  0  0
 0  0  1  1  0  0  1  1  0  0
 0  0  1  1  0  0  1  1  0  0
 0  0  0  1  1  1  1  0  0  0
 0  0  0  0  0  0  0  0  0  0
 0  0  0  0  0  0  0  0  0  0

I can imagine some clunky ways to do this, like saving .pngs of all the letters and then importing them and converting to arrays. Is there a better way using some handy Julia package? Preferably it would not involve saving auxiliary files.

(Remark: Having the array values be 0 or 1 is just for simplicity. If they are e.g. Floats or UInts in some other range, that’s fine.)

2

You could use GitHub - JuliaGraphics/FreeTypeAbstraction.jl: A Julian abstraction layer over FreeType.jl for that

2 Likes
3

The suggestion of ericphanson worked with some modifications, which I’m recording here for posterity (the package linked has no documentation, but works wonderfully once you figure it out). I followed the description in the package readme, but got an error when I ran the line face = FTFont("hack_regular.ttf"). There was no such file. I downloaded the required file from this link. Then I replaced the above call with face = FTFont("path\\to\\file").

The next line of the readme, img, metric = renderface(face, 'C'), also errored. It turns out it requires a third argument which is an integer. This has something to do with the image size, though it’s not exactly the size in pixels. Anyhow, with something like img, metric = renderface(face, 'C',100), I got a result.

1 Like
4

I have suggested this improvement to the readme based on your feedback, hopefully that will help clarify it for the next person!

5

Thanks! However, FYI part of your suggested change also does not work for me. findfont("juliamono") returns nothing, and it is unclear to me how to remedy this.

6

ah ok, in that case you need to choose the name of a font installed on your system. I’ll update my PR to add a comment. juliamono is just an example