When drawing schematics, they should always be done as "TRUE" Black & White. NOT Gray Scale
And I Recommend drawing all lines with "2 bit" width.
Now these can be Scaled up or down, Without any loss of Quality or resolution, especially good when Printing them.
However True B/W Can't be saved as JPG, as it will change to a "Gray Scale" and lose quality.
Always save them as a Tif, Gif or Png file.
But Tif Produces a VERY LARGE FILE.
Gif and Png are much smaller files.