default, when this happens, the program will stop with a fatal error
and refer you to this document.
-It is possible to fix this by editing the character set database used
+It is possible to fix this by editing the character set dictionary used
by the OCR algorithm. But, it is important to get these inputs right
or your client may misrecognise text in future. You *must* read the
documentation here first.
table. We match from left to right.
We do not insist that each glyph is followed by whitespace, and nor do
-we insist that glyphs do not contain whitespace. Our glyph database
+we insist that glyphs do not contain whitespace. Our glyph dictionary
can contain entries which are strict prefixes of other entries - that
is, a glyph for (say) `v' which is the leftmost part of another glyph
for (say) `w'. We resolve these ambiguities by taking the longest
left-hand half of some letter and thinks it is a different letter. If
the part that it did recognise does look like the letter in question,
that isn't wrong. All you need to do is insert the whole of the
-actual letter in the database - move the LH cursor to the start of the
+actual letter in the dictionary - move the LH cursor to the start of the
letter, and the RH cursor to its end, and hit `return' and enter the
correct character. The longest match rule will mean it will prefer
the entry you have just made.
Upper vs lower case - important note regarding `l' and `I'
----------------------------------------------------------
-We maintain separate databases for upper and lower case. At the
+We maintain separate dictionaries for upper case (Upper), lower case
+(Lower), and (initial portions of) mid-phrase words (Word). At the
beginning of each cell in the table, we expect uppercase; in the
middle of a word we expect lowercase; and, unfortunately, after an
inter-word gap, we are not sure.
So any time we see a word starting with `l' or `I', the program has to
ask about it.
-*Do not* make an entry in the character set database mapping `vertical
+After an interword gap, we first search for a Word entry in the
+dictionary. If there is a match we use it. Otherwise we search both
+the uppercase and lowercase dictionaries; if one matches and the other
+doesn't, or one matches a wider character than the other, we use it.
+If that fails to resolve the ambiguity we must ask.
+
+*Do not* make an entry in the character set dictionary mapping `vertical
stick' to `l' or `I'. Instead, select enough of the whole word in
question that no word would start with the other letter, and enter the
-whole word or part of it as a new glyph.
+whole word or part of it as a new glyph as a new Word.
-For example, in the supplied database there is already a glyph for
+For example, in the supplied dictionary there is already a glyph for
`Iron'; this is OK because there are no words which start `lron'.
-Do not make an entry for a string more than 7 characters long;
-currently we cannot cope (and you'll have to remove it manually from
-the charset-15.txt file).
-
Short inter-word gaps
---------------------
*You should check the alleged context before entering a character*.
If it is wrong, you should fix it, rather that just making an entry
-for the uppercase letter in the lowercase database.
+for the uppercase letter in the lowercase dictionary.
Instead, make a new glyph for the last letter of the previous word
plus the (unusually narrow) inter-word space, and end that entry with
-\x20 (yes, type \ x 20).
+a literal space ` '.
For example, you might find that `y<space>G' is treated as
`y<??lowercase>' and the G doesn't get matched. Select the `y<space>'
-region of the bitmap and type `y\x20' into the string box.
-Sorry for this rather poor UI!
+region of the bitmap and type `y ' into the string box.
Overlapping characters - ligatures
Fixing mistakes
---------------
-The OCR query UI allows you to delete things from the glyph database.
-However since you are not guaranteed to actually get an OCR query at
-all if the database contains errors, you shouldn't rely on this.
+The OCR query UI allows you to delete things from the glyph
+dictionary. However since you are not guaranteed to actually get an
+OCR query at all (and since it is not possible to override the
+presence of an entry in the master database with the absence of one in
+the local database), if the dictionary contains errors, you shouldn't
+rely on this.
If you think you have made mistakes answering OCR queries (for
-example, the recognised data is wrong), you should download a fresh
-copy of charset-15.txt from
- http://www.chiark.greenend.org.uk/~ijackson/ypp-sc-tools/master/pctb/charset-15.txt
+example, the recognised data is wrong), you should delete the file
+#local-char*#.txt, which contains your local updates. It will then
+only use the centrally provided (and vetted) master file (which is
+automatically updated when you run the PCTB client, by default).
Enabling interactive character set update
With --edit-charset, when the OCR finds characters it does not
understand, it will put up an OCR resolution query window. This will
display the part of the text it is having trouble with, showing where
-it has got to, and allow you to edit the character set database it
+it has got to, and allow you to edit the character set dictionary it
uses for recognising the text.
*This is subtle* and it is important to understand the way the
answering the program. *Please read this documentation*, which
explains the meaning of the entries you make.
+Also, the character set updates you make will by default be submitted
+to my server so that they can be checked by me and shared with other
+users. See README.privacy.
+
If you need help please ask me (ijackson@chiark.greenend.org.uk, or
Aristarchus on Midnight in game if I'm on line, or ask any pirate of
the crew Special Circumstances if they happen to know where I am
and/or can get in touch).
-
-
-Send me your updates
---------------------
-
-The character set is in the file `charset-15.txt'. When you enter new
-characters, they are added there. If you do this, please email me
-your charset file (ijackson@chiark.greenend.org.uk) so that I can
-include your contributions in future versions. This will also let me
-check that they seem right :-).
-
-In future I may have the program phone home automatically so that I
-can double-check your answers and distribute them in the next version.
~yarrgweb / ypp-sc-tools.db-live.git / blobdiff