updated README

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "img2ascii"
-version = "1.0.0"
+version = "1.1.0"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

README.md

@@ -6,6 +6,8 @@ It can be configured using flags on the command line, a few options of which are
  * Complex ASCII (using the map ``` .'`^",:;Il!i><~+_-?][}{1)(|\/tfjrxnuvczXYUJCLQ0OZmwqpdbkhao*#MW&8%B@$```)
  * [Braille symbols](https://en.wikipedia.org/wiki/Braille_Patterns)
  * Custom character maps (through the `--map` flag)
+ * Output in full colour
+ * Output in grayscale
 
 # Prerequisites
 * [Rust](https://www.rust-lang.org/) (building from source only)
@@ -32,6 +34,8 @@ Of course the output can be customized, by using one (or more) flags.
 ## options
  * -c, --complex: uses the extended character map
  * -C, --colour: Display ASCII art in full 24-bit colour
+ * --background: Colour the background instead of the foreground
+ * -g, --grayscale: Display ASCII art in grayscale
  * -b, --braille: Use braille characters instead of a character map
  * -d, --debug: Print debugging information
  * -f, --full: use the full width of the terminal, instead of fitting the image to the terminal dimensions
@@ -47,14 +51,19 @@ When two or more of these are entered in the same command,
 the program uses the one with the highest precedence, in the order
 `braille > complex > map`.
 
-The flags `--output` and `--colour` also conflict. 
+The flags `--output`, `--colour` and `--grayscale` also conflict. 
 When both are entered, the flag `--output` takes precedence
 (leading to a simple txt file).
 
-Lastly, the flags `--full` and `--width` are mutually exclusive.
+The flags `--full` and `--width` are mutually exclusive.
 When both are entered, the flag `-full` will be applied
 (`full > width`).
 
+Lastly, the flags `--colour` and `--grayscale` are not mutually applicable.
+When both are entered, the flag `--colour` will be applied.
+
+Note also that the `--background` flag requires either `--colour` or `--grayscale` to do anything.
+
 # Documentation
 The program has been documented with RustDoc,
 which can be compiled and viewed with

src/ascii_manipulation.rs

@@ -36,8 +36,10 @@ fn to_ascii(char_map: String, image: DynamicImage) -> Vec<Vec<Ascii>> {
     let mut out: Vec<Vec<Ascii>> = Vec::new();
 
     for pixel in image.pixels() {
-        let ch = char_map.as_bytes()[((get_color(pixel.2) as f32-1.0)/255f32 * l) as usize];
-        str.push(Ascii::new(ch, pixel.2[0], pixel.2[1], pixel.2[2]));
+        let mut ascii = Ascii::new(0, pixel.2[0], pixel.2[1], pixel.2[2]);
+        let ch = char_map.as_bytes()[((ascii.col_depth as f32-1.0)/255f32 * l) as usize];
+        ascii.char = char::from(ch);
+        str.push(ascii);
 
         if pixel.0 == image.width()-1 {
             out.push(str);
@@ -116,7 +118,7 @@ pub fn to_braille_ascii(image: DynamicImage, threshold: u8) -> Vec<Vec<Ascii>> {
                     }
                 }
             }
-            str.push(Ascii { char: char::from_u32(braille_value).unwrap(), rgb: [(r/8) as u8, (g/8) as u8, (b/8) as u8] });
+            str.push(Ascii::new_with_char(char::from_u32(braille_value).unwrap(), (r/8) as u8, (g/8) as u8,  (b/8) as u8));
             }
         out.push(str);
         str = Vec::new();

src/cli.rs

@@ -18,8 +18,20 @@ pub struct Cli {
     #[arg(short = 'c', long)]
     pub complex: bool,
     /// Display ASCII art in full colour
+    ///
+    /// Takes priority over '--grayscale'
     #[arg(short = 'C', long)]
     pub colour: bool,
+    /// Colour the background instead of the foreground
+    ///
+    /// Requires '--colour' or '--grayscale' to be passed
+    #[arg(long)]
+    pub background: bool,
+    /// Display ASCII art in grayscale
+    ///
+    /// incompatible with '--color'
+    #[arg(short= 'g', long)]
+    pub grayscale: bool,
     /// Use braille characters instead of ASCII
     ///
     /// Takes priority over '--complex' and '--map'
@@ -49,7 +61,7 @@ pub struct Cli {
     pub width: Option<u32>,
     /// Save the output to a file, instead of printing to terminal
     ///
-    /// Incompatible with '--colour'
+    /// Incompatible with '--colour' and '--grayscale'
     #[arg(short = 'o', long = "output")]
     pub output: Option<PathBuf>,
 }
@@ -62,6 +74,8 @@ impl Cli {
     pub fn debug_print(&self) {
         debug!("complex: {}", self.complex);
         debug!("colour: {}", self.colour);
+        debug!("background: {}", self.background);
+        debug!("grayscale: {}", self.grayscale);
         debug!("braille: {}", self.braille);
         debug!("debug: {}", self.debug);
         debug!("full: {}", self.full);

src/main.rs

@@ -45,6 +45,10 @@ fn main() {
     if let Some(output) = cli.output {
         print_file(out, output);
     } else {
-        print_terminal(out, cli.colour);
+        if cli.background && (cli.colour || cli.grayscale) {
+            print_terminal_background(out, cli.colour, cli.grayscale);
+        } else {
+            print_terminal(out, cli.colour, cli.grayscale);
+        }
     }
 }

src/model_rgb_ascii.rs

@@ -1,9 +1,15 @@
 //! This module contains the Ascii struct.
 
 /// This struct represents one character + rgb colour.
+///
+/// attributes:
+/// char: char - the character associated with this ASCII value
+/// rgb: [u8; 3] - vec of 3 u8 values representing red, green, and blue respectively
+/// col_depthL u8 - the depth of the rgb values, calculated through the luminosity method
 pub struct Ascii {
     pub char: char,
     pub rgb: [u8; 3],
+    pub col_depth: u8,
 }
 
 impl Ascii {
@@ -21,6 +27,25 @@ impl Ascii {
         Ascii {
             char: char::from(ch),
             rgb: [r, g, b],
+            col_depth: (r as f32 * 0.3 + g as f32 * 0.59 + b as f32 * 0.11) as u8,
+        }
+    }
+
+    /// This function creates a new Ascii instance.
+    ///
+    /// Arguments:
+    /// ch: char - the character
+    /// r: u8 - Red colour value
+    /// g: u8 - Green colour value
+    /// b: u8 - Blue colour value
+    ///
+    /// returns:
+    /// self
+    pub fn new_with_char(ch: char, r: u8, g: u8, b: u8) -> Self {
+        Ascii {
+            char: ch,
+            rgb: [r, g, b],
+            col_depth: (r as f32 * 0.3 + g as f32 * 0.59 + b as f32 * 0.11) as u8,
         }
     }
 }

src/output.rs

@@ -4,7 +4,7 @@ use std::io::{stdout, Write};
 use std::path::PathBuf;
 use std::process::exit;
 use crossterm::execute;
-use crossterm::style::{Color, SetForegroundColor, Print, ResetColor};
+use crossterm::style::{Color, SetForegroundColor, SetBackgroundColor, Print, ResetColor};
 use log::error;
 use crate::model_rgb_ascii::Ascii;
 
@@ -13,7 +13,8 @@ use crate::model_rgb_ascii::Ascii;
 /// arguments:
 /// art: Vec<Vec<Ascii>> - vector of vectors representing the art
 /// in_colour: bool - whether to print in colour or as hard white
-pub fn print_terminal(art: Vec<Vec<Ascii>>, in_colour: bool) {
+/// grayscale: bool - whether to print grayscale
+pub fn print_terminal(art: Vec<Vec<Ascii>>, in_colour: bool, grayscale: bool) {
     for line in art {
         for ascii in line {
             if in_colour {
@@ -21,6 +22,11 @@ pub fn print_terminal(art: Vec<Vec<Ascii>>, in_colour: bool) {
                     SetForegroundColor(Color::Rgb {r: ascii.rgb[0], g: ascii.rgb[1], b: ascii.rgb[2]}),
                     Print(ascii.char),
                     ResetColor);
+            } else if grayscale {
+                let _ = execute!(stdout(),
+                    SetForegroundColor(Color::Rgb {r: ascii.col_depth, g: ascii.col_depth, b: ascii.col_depth}),
+                    Print(ascii.char),
+                    ResetColor);
             } else {
                 print!("{}", ascii.char);
             }
@@ -29,6 +35,36 @@ pub fn print_terminal(art: Vec<Vec<Ascii>>, in_colour: bool) {
     }
 }
 
+/// This function prints ASCII art to the background of stdout.
+///
+/// arguments:
+/// art: Vec<Vec<Ascii>> - vector of vectors representing the art
+/// in_colour: bool - whether to print in colour
+/// grayscale: bool - whether to print grayscale
+pub fn print_terminal_background(art: Vec<Vec<Ascii>>, in_colour: bool, grayscale: bool) {
+    for line in art {
+        for ascii in line {
+            if in_colour {
+                let _ = execute!(stdout(),
+                    SetBackgroundColor(Color::Rgb {r: ascii.rgb[0], g: ascii.rgb[1], b: ascii.rgb[2]}),
+                    SetForegroundColor(Color::Rgb {r: 255-ascii.rgb[0], g: 255-ascii.rgb[1], b: 255-ascii.rgb[2]}),
+                    Print(ascii.char),
+                    ResetColor);
+            } else if grayscale {
+                let _ = execute!(stdout(),
+                    SetBackgroundColor(Color::Rgb {r: ascii.col_depth, g: ascii.col_depth, b: ascii.col_depth}),
+                    SetForegroundColor(Color::Rgb {r: 255-ascii.col_depth, g: 255-ascii.col_depth, b: 255-ascii.col_depth}),
+                    Print(ascii.char),
+                    ResetColor);
+            } else {
+                error!("This should be unreachable!");
+                exit(1);
+            }
+        }
+        println!();
+    }
+}
+
 /// This function prints ASCII art to a file.
 ///
 /// arguments: