ycbcr -> rgb simd

src/color_spaces.rs

@@ -0,0 +1,36 @@
+use std::simd::Simd;
+
+use crate::color_spaces::ColorSpace::RGB;
+
+type MCU = (Simd<f32, 64>, Simd<f32, 64>, Simd<f32, 64>);
+
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub(crate) enum ColorSpace {
+    YCbCr(f32, f32, f32),
+    RGB(f32, f32, f32),
+}
+
+impl ColorSpace {
+    pub(crate) fn convert_ycbcr_to_rgb(image_data: Vec<MCU>) -> Vec<Self> {
+        let mut rgbs = vec![];
+
+        image_data.iter().for_each(|(ys, cbs, crs)| {
+            let cbs = cbs - Simd::splat(128.0);
+            let crs = crs - Simd::splat(128.0);
+
+            let rs = ys + Simd::splat(1.402) * crs;
+            let gs = ys - Simd::splat(0.344136) * cbs - Simd::splat(0.714136) * crs;
+            let bs = ys + Simd::splat(1.772) * cbs;
+
+            rgbs = rs
+                .to_array()
+                .iter()
+                .zip(gs.to_array().iter())
+                .zip(bs.to_array().iter())
+                .map(|((r, g), b)| RGB(*r, *g, *b))
+                .collect();
+        });
+
+        rgbs
+    }
+}

src/decoder.rs

@@ -9,9 +9,9 @@ use rayon::iter::ParallelIterator;
 
 use crate::bitreader::BitReader;
 use crate::coding::{CodingProcess, EntropyCoding};
+use crate::color_spaces::ColorSpace;
 use crate::dequantizer::Dequantizer;
 use crate::entropy_decoder::EntropyDecoder;
-use crate::format::Format;
 use crate::frame_header::Component;
 use crate::huffman_tree::HuffmanClass;
 use crate::idct::IDCT;
@@ -167,7 +167,7 @@ impl Decoder {
         Ok(Parser::new(self.mmap.to_vec(), marlen_map, self.encoding))
     }
 
-    pub fn decode(&mut self) -> Result<Vec<Format>> {
+    pub fn decode(&mut self) -> Result<Vec<ColorSpace>> {
         let parser = self.setup()?;
 
         let code_schema = self.encoding.schema();
@@ -287,15 +287,9 @@ impl Decoder {
                     image_data.push((res[0], res[1], res[2]))
                 }
 
-                let mut ycbcrs = vec![];
+                let raw_image_data = ColorSpace::convert_ycbcr_to_rgb(image_data);
 
-                for (y, cb, cr) in image_data {
-                    for i in 0..64 {
-                        ycbcrs.push(Format::YCbCr(y[i], cb[i], cr[i]));
-                    }
-                }
-
-                Ok(ycbcrs)
+                Ok(raw_image_data)
             }
             _ => todo!(),
         }

src/lib.rs

@@ -11,9 +11,9 @@ pub mod decoder;
 
 mod bitreader;
 mod coding;
+mod color_spaces;
 mod dequantizer;
 mod entropy_decoder;
-mod format;
 pub(crate) mod frame_header;
 pub(crate) mod huffman_tree;
 mod idct;