Select quality

TODO.md

@@ -1,5 +1,9 @@
 Support an alpha channel.
 Improve the PNG interface.
+Actually support terminating early for "progressive" loads
+
+Done:
+Interleave layers instead of having them consecutively. (Bad idea, breaks RLE. Skipping)
 Global parameters to control encoder settings:
 - Quantization level: quant 0
 - Quantization level: quants 1-63
@@ -7,3 +11,4 @@ Global parameters to control encoder settings:
   - Linear term
 - Number of quants to keep, per tile.
 - Whether to use wide or packed representation for the thumbnail block
+Maybe have a second instance of the global parameters block for the alpha channel.

src/compression.rs

@@ -1,18 +1,20 @@
 use std::io::Write;
 
-use crate::{constants::{MAGIC, TILE_SZ, TILE_SZ2}, protocol::{self, ProtocolWriter, ProtocolWriterResult}, quantization, transform};
+use crate::{constants::{MAGIC, TILE_SZ, TILE_SZ2}, protocol::{self, ProtocolWriter, ProtocolWriterResult}, quality_settings::{self, QualitySettings}, quantization, transform};
 
 
 struct PixelTile {
-    // i32: representation that supports Walsh-Hadamard
+    quality: QualitySettings,
     pixels: [i16; TILE_SZ2]
 }
 struct CoefTile {
+    quality: QualitySettings,
     coefs: [i16; TILE_SZ2]
 }
 
 #[derive(Clone, Copy)]
 struct QuantTile {
+    quality: QualitySettings,
     quants: [i16; TILE_SZ2]
 }
 
@@ -21,13 +23,13 @@ pub fn compress<W: Write>(
     width: u32,
     height: u32,
     // n_components: u16,
-    layers: &[&[u8]],
+    layers: &[(QualitySettings, &[u8])],
     writer: &mut protocol::ProtocolWriter<W>
 ) -> ProtocolWriterResult<()> {
 
     // validation
     for l in 0..layers.len() {
-        assert!(layers[l].len() == width as usize * height as usize);
+        assert!(layers[l].1.len() == width as usize * height as usize);
     }
 
     // write header
@@ -36,12 +38,18 @@ pub fn compress<W: Write>(
     writer.write_u32_wide(height)?;
     writer.write_u32_wide(layers.len() as u32)?;
 
+    // write quality settings for each layout
+    for (quality, _) in layers.iter() {
+        writer.write_quality_settings(*quality)?;
+    }
+
+    // build list of tiles
     let mut tiles = vec![];
-    for layer in layers.iter() {
+    for (quality, layer) in layers.iter() {
         for x0 in (0..width).step_by(TILE_SZ) {
             for y0 in (0..height).step_by(TILE_SZ) {
                 let pixel_tile = PixelTile::from_layer(
-                    x0 as usize, y0 as usize, layer, 
+                    x0 as usize, y0 as usize, *quality, layer, 
                     width as usize, height as usize
                 );
                 let coef_tile = CoefTile::from_pixel_tile(&pixel_tile);
@@ -51,13 +59,16 @@ pub fn compress<W: Write>(
         }
     }
 
+    // write the thumbnail block
     for t in tiles.iter() {
         t.write_zero(writer)?;
     }
-    for ti in 0..tiles.len() {
-        let prev = if ti > 0 { Some(tiles[ti - 1]) } else { None };
-        let t = tiles[ti];
+
+    // write the tiles
+    let mut prev: Option<QuantTile> = None;
+    for t in tiles {
         t.write_rest(prev, writer)?;
+        prev = Some(t);
     }
 
     Ok(())
@@ -67,6 +78,7 @@ impl PixelTile {
     fn from_layer(
         x0: usize,
         y0: usize,
+        quality: QualitySettings,
         layer: &[u8],
         width: usize,
         height: usize
@@ -85,7 +97,7 @@ impl PixelTile {
             }
         }
 
-        return PixelTile { pixels };
+        return PixelTile { quality, pixels };
     }
 }
 
@@ -103,19 +115,24 @@ impl CoefTile {
             transform::encode(&mut coefs, x, 8);
         }
 
-        return CoefTile { coefs }
+        return CoefTile { quality: pt.quality, coefs }
     }
 }
 
 impl QuantTile {
     fn from_coef_tile(pt: &CoefTile) -> QuantTile {
         QuantTile {
-            quants: quantization::to_quantized(pt.coefs)
+            quality: pt.quality,
+            quants: quantization::to_quantized(pt.quality, pt.coefs)
         }
     }
 
     fn write_zero<W: Write>(&self, writer: &mut ProtocolWriter<W>) -> ProtocolWriterResult<()> {
+        if self.quality.values[quality_settings::THUMBNAIL_IS_WIDE] != 0 {
             writer.write_i16_wide(self.quants[0])?;
+        } else {
+            writer.write_i16_packed(self.quants[0])?;
+        }
         Ok(())
     }
 

src/decompression.rs

@@ -1,9 +1,8 @@
 use std::io::Read;
 
-use crate::{constants::{MAGIC, TILE_SZ, TILE_SZ2}, protocol::{ProtocolReader, ProtocolReaderError, ProtocolReaderResult}, quantization, transform};
+use crate::{constants::{MAGIC, TILE_SZ, TILE_SZ2}, protocol::{ProtocolReader, ProtocolReaderError, ProtocolReaderResult}, quality_settings::{self, QualitySettings}, quantization, transform};
 
 struct PixelTile {
-    // i32: representation that supports Walsh-Hadamard
     pixels: [i16; TILE_SZ2]
 }
 
@@ -14,6 +13,7 @@ struct CoefTile {
 
 #[derive(Clone, Copy)]
 struct QuantTile {
+    quality: QualitySettings,
     quants: [i16; TILE_SZ2]
 }
 
@@ -36,17 +36,32 @@ pub fn decompress<R: Read>(
     let width_in_tiles = (width as usize + TILE_SZ - 1) / TILE_SZ;
     let height_in_tiles = (height as usize + TILE_SZ - 1) / TILE_SZ;
 
-    let n_tiles = width_in_tiles * height_in_tiles * (n_layers as usize);
-    let mut tiles = vec![QuantTile::new(); n_tiles];
-    for i in 0..n_tiles {
-        tiles[i].load_zero(reader)?;
+    let n_tiles_per_layer = width_in_tiles * height_in_tiles;
+
+    // read quality settings for each layout
+    let mut quality_settings = vec![];
+    for _ in 0..n_layers {
+        quality_settings.push(reader.read_quality_settings()?);
     }
-    for i in 0..n_tiles {
-        let prev = if i > 0 { Some(tiles[i - 1]) } else { None };
+
+    // read thumbnail block
+    let mut tiles = vec![QuantTile::new(); n_tiles_per_layer * n_layers as usize];
+    for l in 0..n_layers {
+        for i in 0..n_tiles_per_layer {
+            tiles[l as usize * n_tiles_per_layer + i].load_zero(
+                quality_settings[l as usize], reader
+            )?;
+        }
+    }
+
+    // read remaining tiles
+    let mut prev: Option<QuantTile> = None;
+    for i in 0..n_tiles_per_layer * n_layers as usize {
         tiles[i].load_rest(
             prev,
             reader
         )?;
+        prev = Some(tiles[i]);
     }
 
     let mut tile_i = 0;
@@ -110,17 +125,29 @@ impl PixelTile {
 
 impl QuantTile {
     fn new() -> QuantTile {
-        QuantTile { quants: [0; TILE_SZ2] }
+        QuantTile { 
+            quality: QualitySettings { values: [0, 0, 0, 0, 0, 0, 0, 0] },
+            quants: [0; TILE_SZ2] 
+        }
     }
     
     fn to_coef_tile(&self) -> CoefTile {
         CoefTile {
-            coefs: quantization::from_quantized(self.quants)
+            coefs: quantization::from_quantized(self.quality, self.quants)
         }
     }
 
-    fn load_zero<R: Read>(&mut self, reader: &mut ProtocolReader<R>) -> ProtocolReaderResult<()> {
+    fn load_zero<R: Read>(
+        &mut self, 
+        quality: QualitySettings, 
+        reader: &mut ProtocolReader<R>
+    ) -> ProtocolReaderResult<()> {
+        self.quality = quality;
+        if quality.values[quality_settings::THUMBNAIL_IS_WIDE] != 0 {
             self.quants[0] = reader.read_i16_wide()?;
+        } else {
+            self.quants[0] = reader.read_i16_packed()?;
+        }
         Ok(())
     }
 

src/main.rs

@@ -8,6 +8,7 @@ mod compression;
 mod constants;
 mod decompression;
 mod protocol;
+mod quality_settings;
 mod quantization;
 mod transform;
 
@@ -33,8 +34,11 @@ fn main() {
 fn hard_main() {
     let (width, height, r, g, b) = load_image();
     let mut writer = ProtocolWriter::new(vec![]);
+
+    let quality_settings = quality_settings::QualitySettings::new(3);
+
     compression::compress(
-        width as u32, height as u32, &[&r, &g, &b],
+        width as u32, height as u32, &[(quality_settings, &r), (quality_settings, &g), (quality_settings, &b)],
         &mut writer
     ).unwrap();
     let compressed = writer.destroy();

src/protocol.rs

@@ -2,6 +2,8 @@ use std::io::{self, ErrorKind, Read, Write};
 
 use thiserror::Error;
 
+use crate::quality_settings::QualitySettings;
+
 #[derive(Clone, Copy)]
 pub struct Header {
     pub bytes: [u8; 3],
@@ -57,6 +59,12 @@ impl<W: Write> ProtocolWriter<W> {
         self.writer.write_all(&[value.version])?;
         Ok(())
     }
+    
+    pub fn write_quality_settings(&mut self, quality: QualitySettings) -> ProtocolWriterResult<()> {
+        self.writer.write_all(&quality.values)?;
+        Ok(())
+    }
+
     pub fn write_u32_wide(&mut self, value: u32) -> ProtocolWriterResult<()> {
         self.writer.write_all(&value.to_le_bytes())?;
         Ok(())
@@ -100,6 +108,13 @@ impl<R: Read> ProtocolReader<R> {
         })
     }
 
+    pub fn read_quality_settings(&mut self) -> ProtocolReaderResult<QualitySettings> {
+        let mut qsettings_buf = [0; 8];
+        self.read_exact(&mut qsettings_buf)?;
+
+        Ok(QualitySettings { values: qsettings_buf })
+    }
+
     pub fn read_u32_wide(&mut self) -> ProtocolReaderResult<u32> {
         let mut u32_buf = [0; 4];
         self.read_exact(&mut u32_buf)?;

src/quality_settings.rs

@@ -0,0 +1,40 @@
+#[derive(Clone, Copy)]
+pub struct QualitySettings {
+    pub values: [u8; 8],
+}
+
+pub const QUANTIZATION_QUANT0_DIVISOR: usize = 0;
+pub const QUANTIZATION_CONSTANT: usize = 1;
+pub const QUANTIZATION_LINEAR: usize = 2;
+pub const QUANTIZATION_N_QUANTS_TO_KEEP: usize = 3;
+pub const THUMBNAIL_IS_WIDE: usize = 4;
+// 5, 6, 7: reserved
+
+
+impl QualitySettings {
+    pub fn new(level: u8) -> Self {
+        // Concept: 
+        // Levels 0, 1, and 2 are incredibly deep fried
+        // Levels 3, 4, 5, 6 are usable with artifacting 
+        // Levels 7, 8, 9 are above what you would seriously use
+        if level == 0 {
+            return QualitySettings { values: [255, 255, 32, 1, 0, 0, 0, 0] };
+        } else if level == 1 {
+            return QualitySettings { values: [192, 192, 24, 2, 0, 0, 0, 0] };
+        } else if level == 2 {
+            return QualitySettings { values: [128, 128, 16, 3, 0, 0, 0, 0] };
+        } else if level == 3 {
+            return QualitySettings { values: [96, 96, 12, 4, 0, 0, 0, 0] };
+
+            // TODO: Levels 4, 5, 6
+
+
+        } else if level == 7 {
+            return QualitySettings { values: [1, 24, 8, 24, 1, 0, 0, 0] };
+        } else if level == 8 {
+            return QualitySettings { values: [1, 12, 4, 48, 1, 0, 0, 0] };
+        } else { // level >= 9
+            return QualitySettings { values: [1, 1, 1, 96, 1, 0, 0, 0] };
+        }
+    }
+}

src/quantization.rs

@@ -1,4 +1,4 @@
-use crate::constants::TILE_SZ2;
+use crate::{constants::TILE_SZ2, quality_settings::{self, QualitySettings}};
 
 const ZIGZAG: [u8; TILE_SZ2] = [
     0 , 1 , 5 , 6 , 14, 15, 27, 28,
@@ -12,12 +12,13 @@ const ZIGZAG: [u8; TILE_SZ2] = [
 ];
 
 pub fn to_quantized(
+    quality_settings: QualitySettings,
     coefs: [i16; TILE_SZ2]
 ) -> [i16; TILE_SZ2] {
     let mut quant: [i16; TILE_SZ2] = [0; TILE_SZ2];
 
     for cf_ix in 0..TILE_SZ2 {
-        let div = divisor(cf_ix);
+        let div = divisor(quality_settings, cf_ix);
         let qval = (coefs[cf_ix] + div / 2) / div;
         quant[ZIGZAG[cf_ix] as usize] = qval
     }
@@ -27,7 +28,7 @@ pub fn to_quantized(
         indices[i] = i;
     }
     indices.sort_by_key(|i| -quant[*i].abs());
-    for i in 4..indices.len() {
+    for i in (quality_settings.values[quality_settings::QUANTIZATION_N_QUANTS_TO_KEEP] as usize)..indices.len() {
         quant[indices[i]] = 0;
     }
 
@@ -35,21 +36,30 @@ pub fn to_quantized(
 }
 
 pub fn from_quantized(
+    quality_settings: QualitySettings,
     quant: [i16; TILE_SZ2]
 ) -> [i16; TILE_SZ2] {
     let mut coefs: [i16; TILE_SZ2] = [0; TILE_SZ2];
     for cf_ix in 0..TILE_SZ2 {
-        let div = divisor(cf_ix);
+        let div = divisor(quality_settings, cf_ix);
         coefs[cf_ix] = quant[ZIGZAG[cf_ix] as usize].wrapping_mul(div);
     }
     coefs
 }
 
-pub fn divisor(cf_ix: usize) -> i16 {
-    if cf_ix == 0 { return 1; }
+pub fn divisor(
+    quality_settings: QualitySettings,
+    cf_ix: usize
+) -> i16 {
+    if cf_ix == 0 { return quality_settings.values[quality_settings::QUANTIZATION_QUANT0_DIVISOR] as i16; }
     let x = cf_ix % 8;
     let y = cf_ix / 8;
-    let div = 32 + (x as i16 + y as i16) * 12;
+    let div = 
+        (quality_settings.values[quality_settings::QUANTIZATION_CONSTANT] as i16).wrapping_add(
+            (x as i16 + y as i16).wrapping_mul(
+                quality_settings.values[quality_settings::QUANTIZATION_LINEAR] as i16
+            )
+        );
     if div==32 && cf_ix != 0 {
         dbg!(cf_ix, x, y, div);
     }