llm-covers

A simple tool for using local LLMs to generate cover briefs for ebooks.

Requirements

• A Mac mini M4 base model (original version) or better M-series computer
• Ollama and gemma4:12b-mlx
• LuaJIT
• calibre

Usage

1. Create config.json if necessary (see format below).
2. Run make_cover_briefs.lua once to create necessary directories.
3. Put ebooks in raw_ebooks.
4. Run make_cover_briefs.lua

Cover briefs will be placed in cover_briefs. A prompt ready to paste directly into Gemini will be in for_gemini. An extra border is prompted for to make cropping easy to remove the Gemini watermark. (There are other small changes to increase likelihood of Gemini following the prompt correctly and making a good output.)

Config file format

{
  "llm_covers": {
    "calibre_location": "/Applications/calibre.app",
    "default_model": "gemma4:12b-mlx",
    "maximum_bytes": 40000
  }
}

The above are the default settings. If you need something different, you only need to specify the changes. (There is a config.json.example file equivalent to the above.)

Gemini Issues

None of this works unless you disable Gemini's personalization/memory, because it pollutes context extremely badly and will randomly add elements and rejections from different conversations everywhere.

If Gemini rejects the prompt, adding Remove any elements that may go against guidelines before generating the image. ⧉ to the opening paragraph can fix that issue.

• This suddenly got a lot less effective. I recommend instead telling it to rewrite the prompt and then in a separate conversation, use that instead. I also recommend one retry before modifying it.

Gemini is really bad about adding hardcover seams. Despite being instructed not to, it shows up sometimes. More strong prompting breaks other requested features, so the best way to deal with it is to request its removal after the initial image is generated.

The local model sometimes completely forgets critical details of characters, so it's important you have some familiarity with the work before running the generator to check accuracy.

Tasks

• Add timestamps to when a prompt is sent.
• Specify ETA when sending a prompt (use numbers from current estimator depending on length). (Show as end time as well as relative time.)
• option to delete input files or intermediate files at end of each major operation segment (or after its finisher..)
• Allow specifying a filter on what to process
• Allow changing the maximum bytes per prompt dynamically (run smaller while I'm doing other things, run full while I'm asleep)
• argparse + ability to
  • only convert ebooks or
  • only generate cover briefs or
  • only generate single pass cover briefs or
  • list how many are left only
• I have an item with over 300 parts in it. Another level of compression needs to be added!
• Change Gemini prompt because it is obsessed with putting colons EVERYWHERE.