Baseline JPEG flag

Author: Lymphatus

docs/USAGE.md

@@ -14,6 +14,17 @@
 
 ##### Advanced compression
 
+- `--jpeg-chroma-subsampling <JPEG_CHROMA_SUBSAMPLING>`  
+  Sets the chroma subsampling for JPEG files. Possible values are:
+    - `4:4:4`
+    - `4:2:2`
+    - `4:2:0`
+    - `4:1:1`
+    - `auto`
+
+- `--jpeg-baseline`  
+  Forces the output to be in baseline JPEG format instead of progressive.
+
 - `--png-opt-level <PNG_OPT_LEVEL>`  
   Sets the optimization level for PNG files. Higher values result in better compression but take longer to complete.
   Possible values are between 0 and 6. Default is 3.

src/compressor.rs

@@ -48,6 +48,7 @@ pub struct CompressionOptions {
     pub keep_dates: bool,
     pub keep_structure: bool,
     pub jpeg_chroma_subsampling: ChromaSubsampling,
+    pub jpeg_baseline: bool,
 }
 
 pub fn start_compression(
@@ -252,6 +253,7 @@ fn build_compression_parameters(
     parameters.keep_metadata = options.exif;
 
     parameters.jpeg.chroma_subsampling = options.jpeg_chroma_subsampling;
+    parameters.jpeg.progressive = !options.jpeg_baseline;
 
     parameters.png.optimization_level = options.png_opt_level;
     parameters.png.force_zopfli = options.zopfli;
@@ -777,6 +779,7 @@ mod tests {
             exif: true,
             png_opt_level: 0,
             jpeg_chroma_subsampling: ChromaSubsampling::Auto,
+            jpeg_baseline: false,
             zopfli: false,
             base_path: PathBuf::new(),
         }

src/main.rs

@@ -139,6 +139,7 @@ fn build_compression_options(args: &CommandLineArgs, base_path: &Path) -> Compre
         exif: args.exif,
         png_opt_level: args.png_opt_level,
         jpeg_chroma_subsampling: parse_jpeg_chroma_subsampling(args.jpeg_chroma_subsampling),
+        jpeg_baseline: args.jpeg_baseline,
         zopfli: args.zopfli,
         base_path: PathBuf::from(base_path),
     }

src/options.rs

@@ -53,10 +53,14 @@ pub struct CommandLineArgs {
     #[arg(long, default_value = "3")]
     pub png_opt_level: u8,
 
-    /// select level for PNG optimization, between [0-6]
+    /// select the chroma subsampling for JPEG files
     #[arg(long, value_enum, default_value = "auto")]
     pub jpeg_chroma_subsampling: JpegChromaSubsampling,
 
+    /// output a baseline JPEG file, progressive (default) otherwise
+    #[arg(long)]
+    pub jpeg_baseline: bool,
+
     /// use zopfli when optimizing PNG files (it may take a very long time to complete)
     #[arg(long)]
     pub zopfli: bool,