Alpha channel of images read with "read-pixels at-x at-

There seems to be a bug on the read-pixels method of the Image class: The generated PNGs have an alpha channel (it isn't necessary), and every pixel is set to 50% opacity, which causes the images to look washed out.

As a workaround, I'm setting the alpha of each pixel to full opacity (1.0) manually, using a couple of for loops, but this is kinda slow (a few seconds per image)

mylImage = new Image. 
mylImage init-with width 400 height 400. 
mylImage read-pixels at-x 0 at-y 0. 
    
for x=0,x<400,x++: 
   for y=0,y<400,y++: 
      mylImage set-alpha-pixel to 1.0 at-x x at-y y.