I also added a pre-processing step to the palettes being used right before they're converted to LAB: It now runs a deduplication step, which has a large performance improvement whenever multiple styles of the same theme are used at the same time.

Finished the rewrite. The user can now provide their own themes. The generation of the LAB version of the image is now parallelized. It now reuses the original image allocation, only mutating its pixels. Added support for providing the theme as a JSON string. Reorganized the CLI. Added batch processing support. Added output folder parameter.

Compiling after merging PR #1 causes this error at src/main.rs:93:10 use of unstable library feature 'is_some_and'

// Print palettes
let color = supports_color::on_cached(supports_color::Stream::Stdout)
    .is_some_and(|level| level.has_16m);

  Compiling dipc v0.5.0 (/home/rochalaj/dipc)
warning: unused imports: `fs::File`, `io::BufReader`
 --> src/cli.rs:1:11
  |
1 | use std::{fs::File, io::BufReader, path::PathBuf, str::FromStr};
  |           ^^^^^^^^  ^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused import: `serde_json::Value`
 --> src/cli.rs:4:5
  |
4 | use serde_json::Value;
  |     ^^^^^^^^^^^^^^^^^

error[E0599]: no variant named `RawJSON` found for enum `ColorPalette`
   --> src/config.rs:151:23
    |
151 |         ColorPalette::RawJSON { .. } => String::new(),
    |                       ^^^^^^^ variant not found in `ColorPalette`
    |
   ::: src/cli.rs:107:1
    |
107 | pub enum ColorPalette {
    | --------------------- variant `RawJSON` not found here

error[E0277]: `ColorPaletteArgGroup` doesn't implement `std::fmt::Display`
  --> src/main.rs:53:13
   |
53 |             cli.color_palette, cli.styles
   |             ^^^^^^^^^^^^^^^^^ `ColorPaletteArgGroup` cannot be formatted with the default formatter
   |
   = help: the trait `std::fmt::Display` is not implemented for `ColorPaletteArgGroup`
   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `writeln` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0599]: no method named `clone` found for struct `ColorPaletteArgGroup` in the current scope
  --> src/main.rs:60:58
   |
60 |     let palettes = match parse_palette(cli.color_palette.clone().get_json(), &cli.styles) {
   |                                                          ^^^^^ method not found in `ColorPaletteArgGroup`
   |
  ::: src/cli.rs:45:1
   |
45 | struct ColorPaletteArgGroup {
   | --------------------------- method `clone` not found for this struct
   |
   = help: items from traits can only be used if the trait is implemented and in scope
   = note: the following trait defines an item `clone`, perhaps you need to implement it:
           candidate #1: `Clone`

error[E0308]: mismatched types
   --> src/main.rs:162:50
    |
162 |             let new_rgb = lab.to_nearest_palette(&palettes).to_rgb();
    |                               ------------------ ^^^^^^^^^ expected `&[Lab]`, found `&Vec<Palette>`
    |                               |
    |                               arguments to this method are incorrect
    |
    = note: expected reference `&[delta::Lab]`
               found reference `&Vec<Palette>`
note: method defined here
   --> src/delta.rs:35:12
    |
35  |     pub fn to_nearest_palette(self, palette: &[Lab]) -> Self {
    |            ^^^^^^^^^^^^^^^^^^       ---------------

error[E0308]: mismatched types
   --> src/main.rs:166:56
    |
166 |         let output_file_name = output_file_name(&path, &cli.color_palette, &palettes);
    |                                ----------------        ^^^^^^^^^^^^^^^^^^ expected `&ColorPalette`, found `&ColorPaletteArgGroup`
    |                                |
    |                                arguments to this function are incorrect
    |
    = note: expected reference `&ColorPalette`
               found reference `&ColorPaletteArgGroup`
note: function defined here
   --> src/config.rs:137:8
    |
137 | pub fn output_file_name(
    |        ^^^^^^^^^^^^^^^^
138 |     input_file_path: &PathBuf,
139 |     color_palette: &ColorPalette,
    |     ----------------------------

Some errors have detailed explanations: E0277, E0308, E0599.
For more information about an error, try `rustc --explain E0277`.
warning: `dipc` (bin "dipc") generated 2 warnings
error: could not compile `dipc` due to 5 previous errors; 2 warnings emitted
error: failed to compile `dipc v0.5.0 (/home/rochalaj/dipc)`, intermediate artifacts can be found at `/home/rochalaj/dipc/target`

cargo v1.69.0 OpenSuse Tumbleweed

how to reproduce

1. git clone https://github.com/doprz/dipc.git
2. cd dipc
3. cargo install --path .

I did not obtain any kind of error installing directly from cargo with: cargo install dipc

• Fixed #10
• Fix .to_nearest_palette() incorrect args
  • expected reference &[delta::Lab]
  • found reference &Vec<Palette>
• Fix non-exhaustive patterns: ColorPalette::RawJSON { .. } not covered
• Change palettes to mutable

• [ ] Add ColorPaletteArgGroup to Cli.
• [ ] Separate choosing one of: color_palette, json_file, or raw_json for easier CLI usage.
• [ ] Refactor code to add Cli args + features:
  • [ ] json_file
  • [ ] raw_json

#[derive(Parser, Debug)]
#[command(author, version, about, long_about = None)]
pub struct Cli {
    // Options
    /// The color palette variation(s) to use
    /// Run with --help instead of -h for a list of all possible values
    ///
    /// Possible values:
    /// - `all` to generate an image for each of the variations
    /// - `none` if you are using a flat theme without variations
    /// - or a comma-delimited list of the names of variations it should use
    #[arg(
        short,
        long,
        value_name = "VARIATIONS",
        default_value = "all",
        verbatim_doc_comment
    )]
    pub styles: ColorPaletteStyles,

    /// Output directory
    #[arg(short, long, value_name = "PATH", default_value = "output")]
    pub output: PathBuf,

    /// Verbose mode (-v, -vv, -vvv)
    #[arg(short, long, action = clap::ArgAction::Count)]
    pub verbose: u8,

    // Arguments
    #[command(flatten)]
    pub color_palette: ColorPaletteArgGroup,

    /// The image(s) to process
    #[arg(value_name = "FILE")]
    pub process: Vec<PathBuf>,
}

#[derive(Args, Debug)]
#[group(required = true, multiple = false)]
struct ColorPaletteArgGroup {
    /// The color palette to use
    /// Run with --help instead of -h for a list of all builtin themes
    ///
    /// Builtin themes:
    /// - catppuccin
    /// - edge
    /// - everforest
    /// - gruvbox
    /// - gruvbox-material
    /// - nord
    /// - rose-pine
    /// - tokyo-night
    #[arg(short, long, value_enum, verbatim_doc_comment)]
    pub color_palette: ColorPalette,

    /// The path to a JSON file with the color palette
    #[arg(short, long)]
    pub json_file: PathBuf,

    /// A JSON string with the color palette (starting with `JSON: {}`)
    #[arg(short, long)]
    pub raw_json: String,
}

I suggest replacing the custom timing code and print statements with an indicatif-based Statusbar

• [ ] Statusbar for loading & processing themes
• [ ] Statusbar for processing each image