Painting a digital image based on data inside a matrix

I need to paint an image with size 6x6 based on a matrix with the same size. Each component of the matrix is a color number between 0-255 in the gray scale. The problem is this matrix is located in an external text file (.txt). How can i read that file, use the matrix and then, paint the 6x6 image?

Here im leaving an image of one example of what i need to do In the example, the images size is 8x9