Attempt to support Proraw dng

src/decoders/ljpeg/decompressors.rs

@@ -144,6 +144,63 @@ pub fn decode_ljpeg_4components(ljpeg: &LjpegDecompressor, out: &mut [u16], widt
   Ok(())
 }
 
+pub fn decode_jlpeg_predictor7_3components(ljpeg: &LjpegDecompressor, out: &mut [u16], x: usize, stripwidth:usize, width: usize, height: usize) -> Result<(),String> {
+  if ljpeg.sof.width*3 < width || ljpeg.sof.height < height {
+    return Err(format!("ljpeg: trying to decode {}x{} into {}x{}",
+                       ljpeg.sof.width*3, ljpeg.sof.height,
+                       width, height).to_string())
+  }
+
+  let ref htable1 = ljpeg.dhts[ljpeg.sof.components[0].dc_tbl_num];
+  let ref htable2 = ljpeg.dhts[ljpeg.sof.components[1].dc_tbl_num];
+  let ref htable3 = ljpeg.dhts[ljpeg.sof.components[2].dc_tbl_num];
+  let mut pump = BitPumpJPEG::new(ljpeg.buffer);
+
+  let base_prediction = 1 << (ljpeg.sof.precision - ljpeg.point_transform -1);
+  out[x]   = (base_prediction + htable1.huff_decode(&mut pump)?) as u16;
+  out[x+1] = (base_prediction + htable2.huff_decode(&mut pump)?) as u16;
+  out[x+2] = (base_prediction + htable3.huff_decode(&mut pump)?) as u16;
+  let skip_x = ljpeg.sof.width - width/3;
+
+  for row in 0..height {
+    let startcol = if row == 0 {x+3} else {x};
+    let prev_row_pos = (row-1) * stripwidth;
+    for col in (startcol..(width+x)).step_by(3) {
+      let pos_l = if col == x {
+        // At start of line predictor starts with start of previous line
+        (row-1)*stripwidth+x
+      } else {
+        // All other cases use the two previous pixels in the same line
+        row*stripwidth+col-3
+      };
+
+      let (p1,p2,p3) = if row == 0 {
+        (out[pos_l],out[pos_l+1],out[pos_l+2])
+      } else {
+        let pos_a = prev_row_pos + col;
+        (((out[pos_l] as u32 + out[pos_a] as u32) >> 1) as u16,
+        ((out[pos_l+1] as u32 + out[pos_a+1] as u32) >> 1) as u16,
+        ((out[pos_l+2] as u32 + out[pos_a+2] as u32) >> 1) as u16)
+      };
+
+      let diff1 = htable1.huff_decode(&mut pump)?;
+      let diff2 = htable2.huff_decode(&mut pump)?;
+      let diff3 = htable3.huff_decode(&mut pump)?;
+      out[row*stripwidth+col+0] = ((p1 as i32) + diff1) as u16;
+      out[row*stripwidth+col+1] = ((p2 as i32) + diff2) as u16;
+      out[row*stripwidth+col+2] = ((p3 as i32) + diff3) as u16;
+    }
+    // Skip extra encoded differences if the ljpeg frame is wider than the output
+    for _ in 0..skip_x {
+      htable1.huff_decode(&mut pump)?;
+      htable2.huff_decode(&mut pump)?;
+      htable3.huff_decode(&mut pump)?;
+    }
+  }
+
+  Ok(())
+}
+
 fn set_yuv_420(out: &mut [u16], row: usize, col: usize, width: usize, y1: i32, y2: i32, y3: i32, y4: i32, cb: i32, cr: i32) {
   let pix1 = row*width+col;
   let pix2 = pix1+3;

src/decoders/ljpeg/mod.rs

@@ -149,7 +149,7 @@ impl<'a> LjpegDecompressor<'a> {
       if marker == m(Marker::SOF3) {
         // Start of the frame, giving us the basic info
         sof.parse_sof(&mut input)?;
-        if sof.precision > 16 || sof.precision < 12 {
+        if sof.precision > 16 || sof.precision < 10 {
           return Err(format!("ljpeg: sof.precision {}", sof.precision).to_string())
         }
       } else if marker == m(Marker::DHT) {
@@ -264,6 +264,12 @@ impl<'a> LjpegDecompressor<'a> {
           c => return Err(format!("ljpeg: {} component files not supported", c).to_string()),
         }
       },
+      7 => {
+        match self.sof.cps {
+          3 => decode_jlpeg_predictor7_3components(self, out, x, stripwidth, width, height),
+          c => return Err(format!("ljpeg: predictor 7, {} component files not supported", c).to_string())
+        }
+      }
       8 => decode_hasselblad(self, out, width),
       p => return Err(format!("ljpeg: predictor {} not supported", p).to_string()),
     }