diff --git a/lib/bitmapper.js b/lib/bitmapper.js
new file mode 100644
index 0000000..924dada
--- /dev/null
+++ b/lib/bitmapper.js
@@ -0,0 +1,120 @@
+function bitRetriever(data, depth) {
+
+  var leftOver = [];
+  var i = 0;
+  function split() {
+    var byte = data[i];
+    i++;
+    switch(depth) {
+      default:
+        throw new Error("unrecognised depth");
+        break;
+/*      case 8:
+        leftOver.push(byte);
+        break;*/
+      case 4:
+        var byte2 = byte & 0x0f;
+        var byte1 = byte >> 4;
+        leftOver.push(byte1, byte2);
+        break;
+      case 2:
+        var byte4 = byte & 3;
+        var byte3 = byte >> 2 & 3;
+        var byte2 = byte >> 4 & 3;
+        var byte1 = byte >> 6 & 3;
+        leftOver.push(byte1, byte2, byte3, byte4);
+        break;
+      case 1:
+        var byte8 = byte & 1;
+        var byte7 = byte >> 1 & 1;
+        var byte6 = byte >> 2 & 1;
+        var byte5 = byte >> 3 & 1;
+        var byte4 = byte >> 4 & 1;
+        var byte3 = byte >> 5 & 1;
+        var byte2 = byte >> 6 & 1;
+        var byte1 = byte >> 7 & 1;
+        leftOver.push(byte1, byte2, byte3, byte4, byte5, byte6, byte7, byte8);
+        break;
+    }
+  }
+  return {
+    get: function(count) {
+      var returner;
+      if (depth === 8) {
+        returner = data.slice(i, i + count);
+        i += count;
+        return returner;
+      }
+      while(leftOver.length < count) {
+        split();
+      }
+      returner = leftOver.slice(0, count);
+      leftOver = leftOver.slice(count);
+      return returner;
+    },
+    resetAfterLine: function() {
+      leftOver.length = 0;
+    }
+  };
+}
+
+exports.dataToBitMap = function(data, width, height, bpp, depth) {
+  if (depth !== 8) {
+    var bits = bitRetriever(data, depth);
+  }
+  var pxData = new Buffer(width * height * 4);
+  var pxPos = 0;
+  var maxBit = Math.pow(2, depth) - 1;
+  var rawPos = 0;
+  var pixelData;
+
+  for(var y = 0; y < height; y++) {
+    for(var x = 0; x < width; x++) {
+      if (depth !== 8) {
+        pixelData = bits.get(bpp);
+      }
+      for (var i = 0; i < 4; i++) {
+        var idx = pixelBppMap[bpp][i];
+        if (depth === 8) {
+          pxData[pxPos] = idx !== 0xff ? data[idx + rawPos] : maxBit;
+        } else {
+          pxData[pxPos] = idx !== 0xff ? pixelData[idx] : maxBit;
+        }
+        pxPos++;
+      }
+      rawPos += bpp;
+    }
+    if (depth !== 8) {
+      bits.resetAfterLine();
+    }
+  }
+
+  return pxData;
+};
+
+var pixelBppMap = {
+  1: { // L
+    0: 0,
+    1: 0,
+    2: 0,
+    3: 0xff
+  },
+  2: { // LA
+    0: 0,
+    1: 0,
+    2: 0,
+    3: 1
+  },
+  3: { // RGB
+    0: 0,
+    1: 1,
+    2: 2,
+    3: 0xff
+  },
+  4: { // RGBA
+    0: 0,
+    1: 1,
+    2: 2,
+    3: 3
+  }
+};
\ No newline at end of file
diff --git a/lib/filter-async.js b/lib/filter-async.js
index 6fb7e68..551ecbb 100644
--- a/lib/filter-async.js
+++ b/lib/filter-async.js
@@ -25,12 +25,19 @@ var util = require('util'),
   Filter = require('./filter');
 
 
-var FilterAsync = module.exports = function(width, height, Bpp, data, options) {
+var FilterAsync = module.exports = function(width, height, Bpp, depth, options) {
     ChunkStream.call(this);
 
-    this._filter = new Filter(width, height, Bpp, data, options, {
+    var buffers = [];
+    var that = this;
+    this._filter = new Filter(width, height, Bpp, depth, options, {
         read: this.read.bind(this),
-        complete: this.emit.bind(this, 'complete')
+        complete: function(width, height) {
+            that.emit('complete', Buffer.concat(buffers), width, height)
+        },
+        write: function(buffer) {
+            buffers.push(buffer);
+        }
     });
 
     this._filter.start();
diff --git a/lib/filter-sync.js b/lib/filter-sync.js
index 1ba810b..5f04db9 100644
--- a/lib/filter-sync.js
+++ b/lib/filter-sync.js
@@ -24,14 +24,20 @@ var SyncReader = require('./sync-reader'),
   Filter = require('./filter');
 
 
-exports.process = function(buffer, width, height, Bpp, outData, options) {
+exports.process = function(buffer, width, height, Bpp, depth, options) {
 
+    var buffers = [];
     var reader = new SyncReader(buffer);
-    var filter = new Filter(width, height, Bpp, outData, options, {
+    var filter = new Filter(width, height, Bpp, depth, options, {
         read: reader.read.bind(reader),
+        write: function(buffer) {
+            buffers.push(buffer);
+        },
         complete: function(){}
     });
 
     filter.start();
     reader.process();
+
+    return Buffer.concat(buffers);
 };
\ No newline at end of file
diff --git a/lib/filter.js b/lib/filter.js
index 83ad820..15077f4 100755
--- a/lib/filter.js
+++ b/lib/filter.js
@@ -20,16 +20,15 @@
 
 'use strict';
 
-var util = require('util'),
-    ChunkStream = require('./chunkstream');
+var util = require('util');
 
 
-var Filter = module.exports = function(width, height, Bpp, data, options, dependencies) {
+var Filter = module.exports = function(width, height, Bpp, depth, options, dependencies) {
 
     this._width = width;
     this._height = height;
     this._Bpp = Bpp;
-    this._data = data;
+    this._depth = depth;
     this._options = options;
 
     this._line = 0;
@@ -49,135 +48,80 @@ var Filter = module.exports = function(width, height, Bpp, data, options, depend
     };
 
     this.read = dependencies.read;
+    this.write = dependencies.write;
     this.complete = dependencies.complete;
+
+    var byteWidth = this._width * this._Bpp;
+    if (this._depth !== 8) {
+        byteWidth = Math.ceil(byteWidth / (8 / this._depth));
+    }
+    this._byteWidth = byteWidth;
 };
 
 Filter.prototype.start = function() {
-    this.read(this._width * this._Bpp + 1, this._reverseFilterLine.bind(this));
-};
-
-var pixelBppMap = {
-    1: { // L
-        0: 0,
-        1: 0,
-        2: 0,
-        3: 0xff
-    },
-    2: { // LA
-        0: 0,
-        1: 0,
-        2: 0,
-        3: 1
-    },
-    3: { // RGB
-        0: 0,
-        1: 1,
-        2: 2,
-        3: 0xff
-    },
-    4: { // RGBA
-        0: 0,
-        1: 1,
-        2: 2,
-        3: 3
-    }
+    this.read(this._byteWidth + 1, this._reverseFilterLine.bind(this));
 };
 
 Filter.prototype._reverseFilterLine = function(rawData) {
 
-    var pxData = this._data,
-        pxLineLength = this._width << 2,
-        pxRowPos = this._line * pxLineLength,
-        filter = rawData[0];
+    var line = new Buffer(this._byteWidth);
 
-    if (filter == 0) {
-        for (var x = 0; x < this._width; x++) {
-            var pxPos = pxRowPos + (x << 2),
-                rawPos = 1 + x * this._Bpp;
+    var filter = rawData[0];
 
-            for (var i = 0; i < 4; i++) {
-                var idx = pixelBppMap[this._Bpp][i];
-                pxData[pxPos + i] = idx != 0xff ? rawData[rawPos + idx] : 0xff;
-            }
+    var xComparison = this._depth === 8 ? this._Bpp : 1;
+    var xBiggerThan = xComparison - 1;
+
+    for (var x = 0; x < this._byteWidth; x++) {
+        var rawByte = rawData[1 + x];
+        switch(filter) {
+            case 0:
+                line[x] = rawByte;
+                break;
+            case 1:
+                var left = x > xBiggerThan ? line[x - xComparison] : 0;
+                line[x] = rawByte + left;
+                break;
+            case 2:
+                var up = this._lastLine ? this._lastLine[x] : 0;
+                line[x] = rawByte + up;
+                break;
+            case 3:
+                var up = this._lastLine ? this._lastLine[x] : 0;
+                var left = x > xBiggerThan ? line[x - xComparison] : 0;
+                var add = Math.floor((left + up) / 2);
+                line[x] = rawByte + add;
+                break;
+            case 4:
+                var up = this._lastLine ? this._lastLine[x] : 0;
+                var left = x > xBiggerThan ? line[x - xComparison] : 0;
+                var upLeft = x > xBiggerThan && this._lastLine
+                        ? this._lastLine[x - xComparison] : 0;
+                var add = PaethPredictor(left, up, upLeft);
+                line[x] = rawByte + add;
+                break;
         }
 
-    } else if (filter == 1) {
-        for (var x = 0; x < this._width; x++) {
-            var pxPos = pxRowPos + (x << 2),
-                rawPos = 1 + x * this._Bpp;
-
-            for (var i = 0; i < 4; i++) {
-                var idx = pixelBppMap[this._Bpp][i],
-                    left = x > 0 ? pxData[pxPos + i - 4] : 0;
-
-                pxData[pxPos + i] = idx != 0xff ? rawData[rawPos + idx] + left : 0xff;
-            }
-        }
-
-    } else if (filter == 2) {
-        for (var x = 0; x < this._width; x++) {
-            var pxPos = pxRowPos + (x << 2),
-                rawPos = 1 + x * this._Bpp;
-
-            for (var i = 0; i < 4; i++) {
-                var idx = pixelBppMap[this._Bpp][i],
-                    up = this._line > 0 ? pxData[pxPos - pxLineLength + i] : 0;
-
-                pxData[pxPos + i] = idx != 0xff ? rawData[rawPos + idx] + up : 0xff;
-            }
-
-        }
-
-    } else if (filter == 3) {
-        for (var x = 0; x < this._width; x++) {
-            var pxPos = pxRowPos + (x << 2),
-                rawPos = 1 + x * this._Bpp;
-
-            for (var i = 0; i < 4; i++) {
-                var idx = pixelBppMap[this._Bpp][i],
-                    left = x > 0 ? pxData[pxPos + i - 4] : 0,
-                    up = this._line > 0 ? pxData[pxPos - pxLineLength + i] : 0,
-                    add = Math.floor((left + up) / 2);
-
-                 pxData[pxPos + i] = idx != 0xff ? rawData[rawPos + idx] + add : 0xff;
-            }
-
-        }
-
-    } else if (filter == 4) {
-        for (var x = 0; x < this._width; x++) {
-            var pxPos = pxRowPos + (x << 2),
-                rawPos = 1 + x * this._Bpp;
-
-            for (var i = 0; i < 4; i++) {
-                var idx = pixelBppMap[this._Bpp][i],
-                    left = x > 0 ? pxData[pxPos + i - 4] : 0,
-                    up = this._line > 0 ? pxData[pxPos - pxLineLength + i] : 0,
-                    upLeft = x > 0 && this._line > 0
-                            ? pxData[pxPos - pxLineLength + i - 4] : 0,
-                    add = PaethPredictor(left, up, upLeft);
-
-                pxData[pxPos + i] = idx != 0xff ? rawData[rawPos + idx] + add : 0xff;
-            }
-        }
+        //if (x === 5) {
+        //    console.log("R", line[3], "G", line[4], "B", line[5]);
+        //}
     }
 
-
     this._line++;
+    this._lastLine = line;
+    this.write(line);
 
-    if (this._line < this._height)
-        this.read(this._width * this._Bpp + 1, this._reverseFilterLine.bind(this));
-    else
-        this.complete(this._data, this._width, this._height);
+    if (this._line < this._height) {
+        this.read(this._byteWidth + 1, this._reverseFilterLine.bind(this));
+    } else {
+        this._lastLine = null;
+        this.complete(this._width, this._height);
+    }
 };
 
 
+Filter.prototype.filter = function(pxData) {
 
-
-Filter.prototype.filter = function() {
-
-    var pxData = this._data,
-        rawData = new Buffer(((this._width << 2) + 1) * this._height);
+    var rawData = new Buffer(((this._width << 2) + 1) * this._height);
 
     for (var y = 0; y < this._height; y++) {
 
diff --git a/lib/packer.js b/lib/packer.js
index c8b74a8..96605d4 100755
--- a/lib/packer.js
+++ b/lib/packer.js
@@ -50,8 +50,9 @@ Packer.prototype.pack = function(data, width, height) {
     this.emit('data', this._packIHDR(width, height));
 
     // filter pixel data
-    var filter = new Filter(width, height, 4, data, this._options, {});
-    var data = filter.filter();
+    //TODO {}
+    var filter = new Filter(width, height, 4, 8, this._options, {});
+    var data = filter.filter(data);
 
     // compress it
     var deflate = zlib.createDeflate({
diff --git a/lib/parser-async.js b/lib/parser-async.js
index a9453b8..17d0e9a 100644
--- a/lib/parser-async.js
+++ b/lib/parser-async.js
@@ -25,7 +25,8 @@ var util = require('util'),
     zlib = require('zlib'),
     ChunkStream = require('./chunkstream'),
     FilterAsync = require('./filter-async'),
-    Parser = require('./parser');
+    Parser = require('./parser'),
+    bitmapper = require('./bitmapper');
 
 
 var ParserAsync = module.exports = function(options) {
@@ -72,26 +73,36 @@ ParserAsync.prototype._inflateData = function(data) {
     this._inflate.write(data);
 };
 
-ParserAsync.prototype._createData = function(width, height, bpp) {
-    this._data = new Buffer(width * height * 4);
+ParserAsync.prototype._createData = function(width, height, bpp, depth) {
+
+    this._bpp = bpp;
+    this._depth = depth;
+
     this._filter = new FilterAsync(
       width, height,
       bpp,
-      this._data,
+      depth,
       this._options
     );
-    return this._data;
 };
 
 ParserAsync.prototype._finished = function(data) {
-    // no more data to inflate
-    this._inflate.end();
+    if (!this._inflate) {
+        this.emit('error', 'No Inflate block');
+    } else {
+        // no more data to inflate
+        this._inflate.end();
+    }
     this.destroySoon();
 };
 
 ParserAsync.prototype._complete = function(data, width, height) {
 
-    data = this._parser.reverseFiltered(data, width, height);
+    data = bitmapper.dataToBitMap(data, width, height,
+      this._bpp,
+      this._depth);
+
+    data = this._parser.reverseFiltered(data, this._depth, width, height);
 
     this.emit('parsed', data);
 };
diff --git a/lib/parser-sync.js b/lib/parser-sync.js
index 71bcbdf..e885816 100644
--- a/lib/parser-sync.js
+++ b/lib/parser-sync.js
@@ -24,7 +24,8 @@
 var zlib = require('zlib'),
     SyncReader = require('./sync-reader'),
     FilterSync = require('./filter-sync'),
-    Parser = require('./parser');
+    Parser = require('./parser'),
+  bitmapper = require('./bitmapper');
 
 
 var ParserSync = module.exports = function(buffer, options) {
@@ -51,15 +52,19 @@ var ParserSync = module.exports = function(buffer, options) {
 
     var data = zlib.inflateSync(inflateData);
 
-    FilterSync.process(
+    data = FilterSync.process(
       data,
       this._width, this._height,
       this._bpp,
-      this._data,
+      this._depth,
       this._options
     );
 
-    this.data = this._parser.reverseFiltered(this._data, this._width, this._height);
+    this._data = bitmapper.dataToBitMap(data, this._width, this._height,
+      this._bpp,
+      this._depth);
+    // todo yuck
+    this.data = this._parser.reverseFiltered(this._data, this._depth, this._width, this._height);
 };
 
 ParserSync.prototype._handleError = function(err) {
@@ -78,10 +83,11 @@ ParserSync.prototype._inflateData = function(data) {
     this._inflateDataList.push(data);
 };
 
-ParserSync.prototype._createData = function(width, height, bpp) {
+ParserSync.prototype._createData = function(width, height, bpp, depth) {
     this._data = new Buffer(width * height * 4);
     this._bpp = bpp;
     this._width = width;
     this._height = height;
+    this._depth = depth;
     return this._data;
 };
diff --git a/lib/parser.js b/lib/parser.js
index 680154f..ac138ef 100644
--- a/lib/parser.js
+++ b/lib/parser.js
@@ -164,7 +164,7 @@ Parser.prototype._parseIHDR = function(data) {
   //     'compr', compr, 'filter', filter, 'interlace', interlace
   // );
 
-  if (depth != 8) {
+  if (depth !== 8 && depth !== 4 && depth !== 2 && depth !== 1) {
     this.error(new Error('Unsupported bit depth ' + depth));
     return;
   }
@@ -187,17 +187,17 @@ Parser.prototype._parseIHDR = function(data) {
 
   this._colorType = colorType;
 
-  this._data = this.createData(width, height, colorTypeToBppMap[this._colorType]);
+  this.createData(width, height, colorTypeToBppMap[this._colorType], depth);
 
   this._hasIHDR = true;
 
   this.metadata({
     width: width,
     height: height,
+    depth: depth,
     palette: !!(colorType & constants.COLOR_PALETTE),
     color: !!(colorType & constants.COLOR_COLOR),
-    alpha: !!(colorType & constants.COLOR_ALPHA),
-    data: this._data
+    alpha: !!(colorType & constants.COLOR_ALPHA)
   });
 
   this._handleChunkEnd();
@@ -298,10 +298,10 @@ Parser.prototype._parseIEND = function(data) {
   this.finished();
 };
 
-Parser.prototype.reverseFiltered = function(data, width, height) {
+Parser.prototype.reverseFiltered = function(data, depth, width, height) {
 
   if (this._colorType == 3) { // paletted
-
+    //console.log("paletted");
     // use values from palette
     var pxLineLength = width << 2;
 
@@ -312,10 +312,31 @@ Parser.prototype.reverseFiltered = function(data, width, height) {
         var pxPos = pxRowPos + (x << 2),
           color = this._palette[data[pxPos]];
 
+        if (!color) {
+          console.error("data - " + data[pxPos] + " got no colour");
+          console.log("depth is ", depth);
+          return;
+        }
+
         for (var i = 0; i < 4; i++)
           data[pxPos + i] = color[i];
       }
     }
+  } else if (depth !== 8) {
+    //console.log("adjusting");
+    var pxLineLength = width << 2;
+    var maxOutSample = 255;
+    var maxInSample = Math.pow(2, depth) - 1;
+
+    for (var y = 0; y < height; y++) {
+      var pxRowPos = y * pxLineLength;
+
+      for (var x = 0; x < width; x++) {
+        var pxPos = pxRowPos + (x << 2);
+        for (var i = 0; i < 4; i++)
+          data[pxPos + i] = Math.floor((data[pxPos + i] * maxOutSample) / maxInSample + 0.5);
+      }
+    }
   }
   return data;
 };
diff --git a/lib/png.js b/lib/png.js
index 95b1542..0fe8558 100755
--- a/lib/png.js
+++ b/lib/png.js
@@ -112,9 +112,7 @@ PNG.prototype.end = function(data) {
 PNG.prototype._metadata = function(metadata) {
     this.width = metadata.width;
     this.height = metadata.height;
-    this.data = metadata.data;
 
-    delete metadata.data;
     this.emit('metadata', metadata);
 };
 
diff --git a/test/test.js b/test/test.js
index 53b7a40..dadd8d9 100644
--- a/test/test.js
+++ b/test/test.js
@@ -12,26 +12,36 @@ fs.readdir(__dirname + '/in/', function(err, files) {
 
         var expectedError = false;
         if (file.match(/^x/) ||
-            file.match(/^...i/) || // interlace
-            file.match(/^......(01|02|04|16)/) || // 1/2/4/16 bit
-            file.match(/^basn3p(01|02|04)/) // 2/4/16 colour palette
+            file.match(/^...i/) ||// interlace
+            file.match(/^......(16)/) // 1/2/4/16 bit
         ) {
             expectedError = true;
         }
 
-        if (!expectedError) {
-            var data = fs.readFileSync(__dirname + '/in/' + file);
+        var data = fs.readFileSync(__dirname + '/in/' + file);
+        try {
+            console.log("Sync: parsing..", file);
             var png = PNG.sync.read(data);
-
-            var outpng = new PNG();
-            PNG.adjustGamma(png);
-            outpng.data = png.data;
-            outpng.width = png.width;
-            outpng.height = png.height;
-            outpng.pack()
-              .pipe(fs.createWriteStream(__dirname + '/outsync/' + file));
+        } catch (e) {
+            if (!expectedError) {
+                console.log(e);
+                console.log(e.stack);
+            }
+            return;
         }
 
+        if (expectedError) {
+            console.log("Error expected, parsed fine", file);
+        }
+
+        var outpng = new PNG();
+        PNG.adjustGamma(png);
+        outpng.data = png.data;
+        outpng.width = png.width;
+        outpng.height = png.height;
+        outpng.pack()
+          .pipe(fs.createWriteStream(__dirname + '/outsync/' + file));
+
         fs.createReadStream(__dirname + '/in/' + file)
             .pipe(new PNG())
             .on('error', function(err) {