README.md

FONS
====
A tool to make fonts out of bitmap images.

Tools needed
------------
- Gimp
- Gimp G'MIC plugin
- Autotrace
- Fontforge with Autotrace



Process
-------

### Preparing the image


#### Get a bitmap image of characters (crop unnecessary white parts for a faster process, you can use Gimp's automatic crop for that).

![](http://osp.kitchen/api/osp.tools.fons/raw/input/scan_bitmap.jpg)
:    A scan in bitmap

![](http://osp.kitchen/api/osp.tools.fons/raw/input/scan_gray_1200dpi.jpg)
:    A scan in gray levels

![](http://osp.kitchen/api/osp.tools.fons/raw/input/rasterized_ospDIN.png)
:    A rasterized font





#### Levels (have a white background, black characters but still shades of gray)

![](http://osp.kitchen/api/osp.tools.fons/raw/documentation/01-bitmap_levels.png)



#### Small boost 

Scale up the image to something like 254% with the "Sinc (Lanczos 3)" algorithm. We choose on purpose a non-round number of scaling to break the bitmap patterns.

![](http://osp.kitchen/api/osp.tools.fons/raw/documentation/02-scale-254percent.png)



#### Sharpen with "Unsharp mask"

Put the amount to the maximum and then search for the point where you don't see 

![bad](http://osp.kitchen/api/osp.tools.fons/raw/documentation/03-sharpen-too_few.png)
:    Radius too small

![ok](http://osp.kitchen/api/osp.tools.fons/raw/documentation/03-sharpen-ok.png)

![bad](http://osp.kitchen/api/osp.tools.fons/raw/documentation/03-sharpen-too_much.png)



#### Big boost

Scale up to 403% (check on notebook or with PierreH if it's enough)

![](http://osp.kitchen/api/osp.tools.fons/raw/documentation/04-big_boost.png)



#### Threshold


![bad](http://osp.kitchen/api/osp.tools.fons/raw/documentation/05-threshold-bad.png)


![ok](http://osp.kitchen/api/osp.tools.fons/raw/documentation/05-threshold-ok.png)


#### Baseline

When importing a bitmap, Fontforge scales up/down the bitmap so that it fits into the glyph box. If we use GlyphTracer 1.4, this ends up with different scales of glyphs. In order to prevent this, we can put a black rectangle of the height of the maximum ascendant and maximum descendant.

![baseline](http://osp.kitchen/api/osp.tools.fons/raw/documentation/06-baseline.png)


#### Bitmap

- Change the color mode to Indexed mode with 1 black/white bit.
- Save as a .bmp file.


### GlyphTracer

- Launch GlyphTracer and feed in the .bmp image (otherwise it will complain).
- For each given glyph, click on the letter you want to use.
- Change the characters subset in the bottom left dropdown menu to select more glyphs.



IMPORTANT: If you zoom out to select the letters, don't forget to go back to zoom 1 before generating the font file. Don't close GlyphTracer before checking the .sfd file, then you can export again if you forgot to zoom back in.


### Merging fonts

In case you want to complete an existing font, you can use the script `mergeFonts.py`.

    python mergeFonts.py fonte1.ufo fonte2.ufo ...  fonte17.ufo fonte-out.ufo


### Metrics and kernings

A big part of type design is about managing the white space around the letters (metrics) and exceptions for specific couples of letters (kernings).

- For the metrics, we make an auto-spacing while generating the .sfd file with GlyphTracer.
- For the kernings, you can try the tool (Kernagic)[https://github.com/hodefoting/kernagic].

But if you want to get back metric and kerning data from an existing font, you can use the script `mergeSpacing.py`. It can be any font format than `.otf`.

   python mergeSpacing.py font.otf original-font.otf spaced-font.otf



Troubleshooting
---------------

### My image is too big to manipulate it.
Split it into several images and generate several .sfd files. Then you can merge the fonts with the script `mergeFonts.py`.


### I have empty and very small width when I open a glyph in Fontforge.
You probably generated the .sfd with a zoom level different than 1.


### I see several letters in ony glyph.
You probably generated the .sfd with a zoom level different than 1.