BitFonter 3 font point and pixel size

pthomas505
pthomas505 Posts: 57
in Type Design Software
How does one determine what to set the various values to in the BitFonter 3 "Font point and pixel size" dialog box?


Answers

  • John Hudson
    John Hudson Posts: 3,541
    I’ve not used BitFonter, but the numbers are going to control bitmap rasterisation. The three number are relative, so my guess is that as you change one or two of the numbers the third one will adjust automatically. You probably want to lock the resolution once you have determined your target resolution, e.g. 96 (this is a pixel-per-inch number, and 96 ppi is used to calculate virtual px units in CSS). Now you have a choice of deciding either the ppm bitmap size—the number of pixels assigned to the height of the body of the font at that resolution at a given point size—, or the point size.

    So, for example, you might decide you want to target a 16 ppm bitmap size, if you enter that value in the first field, the point size field should automatically update to show what that ppm size equals in points at the target resolution (there are 72 points in an inch, so: 72/(96/16)=12pt).

    Or, you might decide you want to target a 20pt type size in the lower field, in which case the ppm bitmap size should automatically update to show how many pixels are available at that point size: 96/(72/20)=27ppm (pixels are always whole units, so rounding occurs).
  • Mark Simonson
    Mark Simonson Posts: 1,765
    edited November 2
    I’ve used BitFonter in the past and what John says is correct. The numbers do change automatically when you change one of them, unless you uncheck the Lock Resolution checkbox (but I can’t think of a reason you’d want to do that). (On second thought, I can. Apple's bitmap fonts for the original Macintosh had a relatively larger PPM than the nominal point size.)
  • pthomas505
    pthomas505 Posts: 57
    Suppose I designed a bitmap font such that the highest filled in pixel is seven pixels above the baseline, the lowest filled in pixel is two pixels below the baseline, and there should be one pixel of empty space between each line. Does that mean that I should set the "Pixel size (PPM)" field to 7 + 2 + 1 = 10 pixels?
  • John Hudson
    John Hudson Posts: 3,541
    Yes, that is correct. You would be designing a 10ppm bitmap font. The point size(s) to which that would correspond would be determined by the resolution.
  • pthomas505
    pthomas505 Posts: 57
    If the largest width happened to be greater than the largest height, would one use that instead?
  • John Hudson
    John Hudson Posts: 3,541
    No. Bitmap size is always determined by height: it is a measure of how many pixels are assigned to the body (em) height. Width is arbitrary.

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