added a little more to the readme

README.md

@@ -1,7 +1,7 @@
 # Font Helper for Karlos
 
 ## Features
-- take images containing several chars and break them down into individual images
+- take images containing several chars and break them down into individual images (splitting)
   - images containing several consecutive characters in 2D arrangement
   - images containing several arbitrary characters in 1D arrangement
   - images containing a single character
@@ -10,3 +10,29 @@
 
 ## Example
 `cargo run -- split-and-create --index example/index.json --font-dir font --encoding BitPerPix4 font.sff`
+
+## Command Line Arguments
+A font is specified by its glyph width, glyph height, and one or more _splitters_ (see below).
+
+Commands are (use `<command> --help` to get more information):
+- _Inspect_ (`inspect`): inspect a font, printing attributes and symbols.
+- _Create_ (`create`): from a set of images containing single glyphs, create an sff font file.
+  - the file name of the glyph images should be its number in base 10, so the glyph for `a` is `97.png`
+- _Split_ (`split`): parse a sequence of splitters and create individual images.
+- _SplitAndCreate_ (`split-and-create`): apply the above two commands in sequence.
+
+# Splitter
+For an example of how to specify these splitters, refer to `example/index.json`.
+
+The following variants exist:
+- _Table_: a rectangular grid of glyphs, numbered ascending left to right and top to bottom.
+  - `path: String`: file path to image
+  - `nrows: Int`: number of rows
+  - `ncols: Int`: number of columns
+  - `start_number: Int`: first glyph number
+- _Individual_: one row of glyphs, each with an individual (non-consecutive) number.
+  - `path: String`: file path to image
+  - `numbers: [Int]`: list of glyph numbers
+- _Single_: a single glyph.
+  - `path: String`: file path to image
+  - `number: Int`: the glyph number