calibre friday preview releases

[kovidgoyal]

A new preview build of calibre is available, and it adds a big new feature to the
ebook editor (Edit book): grammar checking and suggestions for rewriting sentences.
Please try it out and report any problems you find, so they can be fixed before
the next release. Note that it runs completely on your computer and does not use LLMs,
it uses rules based grammar checkers and also seq2seq models.


Grammar checking
------------------

As you edit HTML files, grammar, style and typography issues are underlined in
the code view, just like spelling mistakes. Right click an underlined issue to:

* Replace it with one of the suggested corrections
* Ignore it for the current session
* Stop checking for that kind of issue altogether
* See an explanation of the issue

Hovering the mouse over an issue describes it, and Shift+F8 jumps to the next
issue in the current file. Corrections change only the text, so formatting such
as bold and italics is preserved, and each correction can be undone in one step.

To review the whole book at once, use Tools->Check grammar (Shift+F7). It lists
every issue in the book along with explanations and suggested replacements.
You can correct issues, jump to them in the editor, filter the list by text and
type of issue, ignore issues, and disable (and later re-enable) rules you are
not interested in. Turn on the "Picky" option to also flag stylistic issues
that are not errors, such as wordiness.

Grammar checking works for many languages. As with spell checking, the
language comes from the book's metadata and from lang attributes in the HTML,
so books containing text in several languages are checked correctly. Only
paragraphs that have changed are checked again, and the checking runs in the
background so it does not slow down editing.

For English, there is also a "Deep check" option, which checks every sentence
with a neural network as well. It finds errors that the rules miss, but it is
slower. Once its neural network has been downloaded, it is also used to rank
the suggested corrections for English text, putting the best ones first.


Sentence rewrite suggestions
------------------------------

For English text, a neural network can suggest rewrites of sentences. You
choose the kinds of suggestions you want: fixing grammar, making a sentence
more fluent or clearer, simpler or more formal, or paraphrasing it.

* Right click a sentence and choose "Suggest rewrites for the sentence"
(Ctrl+Shift+F8) to see suggestions for it in a popup
* Open the View->Rewrite suggestions panel, which follows the sentence your
cursor is in as you move through the text
* In the Check grammar tool, suggestions are shown for the sentence
containing the selected issue

Each suggestion shows the changes it makes to the sentence. Click "Apply" to
rewrite the sentence. Its formatting is kept, and you can undo the rewrite in
one step. Suggestions that would change text that must not change, such as
code, are not shown, and neither are suggestions that would add new grammar
issues.


What you need to do to use them
---------------------------------

Grammar checking and rewrite suggestions are turned on in the editor, but they
need data that is not included with calibre. calibre asks before downloading
anything. Once the data is downloaded, all checking and suggestions run
entirely on your computer and no text is ever sent anywhere.

1. Language data for grammar checking: the data for each language is
downloaded the first time it is needed. Right click in the editor and
choose to download it, or download it from the Tools->Check grammar
tool. Until it is downloaded, that language is not checked.

2. Neural network for Deep check (English only): downloaded when you first
turn on Deep check in the Check grammar tool. It is about 150 MB.

3. Neural network for rewrite suggestions (English only): downloaded the
first time you ask for suggestions. It is large, about 1.2 GB.

Generating suggestions is much faster on a GPU. By default calibre uses the
GPU if it is supported and turns out to be faster than the CPU. When the GPU
might be used, versions of the neural network for both the CPU and the GPU are
downloaded, so the download is considerably larger (around 4 GB in total for
the rewrite suggestions). If you do not want this, set "Use the GPU for grammar
neural networks" to "Never" in Preferences->Editor settings, and only the CPU
version is downloaded.

Underlining of grammar issues can be turned off in Preferences->Editor
settings, and its color can be changed with the new GrammarError entry in the
editor themes.


Limitations
-------------

* Sentence rewrite suggestions and the Deep check are English only. Grammar
checking with the rules works for many other languages, but text in other
languages gets neither rewrite suggestions nor neural network checks.
* Grammar checking is done only in the ebook editor, in HTML files.
* The neural network downloads are large, and generating suggestions on a
CPU can be slow, especially on older computers.
* Like any automated tool, grammar checks and rewrites are suggestions, not
infallible. They can miss errors, flag correct text, or suggest rewrites
that change the meaning of a sentence, particularly in fiction, dialogue
and deliberately unconventional prose. Read every suggestion before
applying it.

[Comfy.n]

Paraphrase option is cool idea. I use it all the time by asking Google AI Overview for quick alternatives, and I wish this forum had such a tool available in the advanced posting editor, lol.