//Decompress byte array into aBitmap with help of width, length and bitdepth
public static AccessibleBitmap Decompress(byte[] source, int width, int height, int pixelBytes)
{
//Create a empty AccessibleBitmapBytewise class with the correct dimensions and color channels
AccessibleBitmapBytewise outputBitmap = new AccessibleBitmapBytewise(new AccessibleBitmap(width, height, pixelBytes));
//Initialize
byte[] inBytes; //Stores the bytes to feed to the decompressor
byte[] outBytes = source; //Stores the bytes which are left by the previous decompressed channel: starts with all the input data
//Loop trough all color channels
for (int i = 0; i < pixelBytes; i++)
{
//Read compression type from outBytes & copy the rest of them to inBytes so they can be used for the next channel
int compressionType = outBytes[0];
inBytes = new byte[outBytes.Length - 1];
Array.Copy(outBytes, 1, inBytes, 0, inBytes.Length);
//Decompress using the correct compression type
switch (compressionType)
{
//Uncompressed
case 0:
outputBitmap = UncompressedBitmapCompressorBytewise.Decompress(inBytes, outputBitmap, out outBytes, i);
break;
//Individual compressed bit channels added together
case 1:
outputBitmap = BitLayerVaryingCompressor.Decompress(inBytes, outputBitmap, out outBytes, i);
break;
//Color channel compressed as integers
case 2:
outputBitmap = ByteArrayCompressorBytewise.Decompress(inBytes, outputBitmap, out outBytes, i);
break;
//Run length compression
case 3:
outputBitmap = RunLengthEncodingCompressorBytewise.Decompress(inBytes, outputBitmap, out outBytes, i);
break;
//Run length encoding vertical
case 4:
outputBitmap = RunLengthEncodingCompressorVerticalBytewise.Decompress(inBytes, outputBitmap, out outBytes, i);
break;
//To add a decompression type add a new case like the existing ones
//Unknown compression type: error
default:
throw new Exception("Unexisting compression type");
}
}
return(outputBitmap.GetAccessibleBitmap());
}
//Compress aBitmap into byte array
public static byte[] Compress(AccessibleBitmap source)
{
//Loop trough all layers of bytes, where possible at the same time
AccessibleBitmapBytewise aBitmap = new AccessibleBitmapBytewise(source);
byte[][] byteLayers = new byte[source.pixelBytes][];
Parallel.For(0, source.pixelBytes, (z, state) => //for(int z = 0; z < source.pixelBytes; z++)
{
//Compress image using all different compression techniques, where possible at the same time
byte[][] compressionTechniques = new byte[5][];
Parallel.For(0, compressionTechniques.Length, (i, state2) =>
{
switch (i)
{
//Uncompressed (only used if no compression technique is smaller)
case 0:
compressionTechniques[i] = UncompressedBitmapCompressorBytewise.Compress(aBitmap, z);
break;
//Split color channel in its bit channels and apply compression over them
case 1:
compressionTechniques[i] = BitLayerVaryingCompressor.Compress(aBitmap, z);
break;
//Compress color channel as an integer array using several techniques
case 2:
compressionTechniques[i] = ByteArrayCompressorBytewise.Compress(aBitmap, z);
break;
//Run length compression: save the length of a sequence of pixels with the same color instead of saving them seperately
case 3:
compressionTechniques[i] = RunLengthEncodingCompressorBytewise.Compress(aBitmap, z);
break;
//Run length compression vertical: run length compression, but scan the pixels horizontally, becouse with some images this yields better results
case 4:
compressionTechniques[i] = RunLengthEncodingCompressorVerticalBytewise.Compress(aBitmap, z);
break;
//To add a compression technique, add a new case like the existing ones and increase the length of new byte[??][]
}
});
//Choose the smallest compression type
//Initialize
int smallestID = 0; //The ID of the smallest compression type
int smallestSize = int.MaxValue; //The size ofthe smallest compression type: int.MaxValue is assigned to make sure that the first compression to be checked will be smaaller than this value
//Loop trough all saved compression techniques
for (int i = 0; i < compressionTechniques.Length; i++)
{
//If the current technique is smaller than the smallest technique which has been checked
if (compressionTechniques[i].Length < smallestSize)
{
//Mark this technique as smallest
smallestSize = compressionTechniques[i].Length;
smallestID = i;
}
}
//Merge the number of the compression type of this layer with corresponding byte array
byteLayers[z] = new byte[compressionTechniques[smallestID].Length + 1];
byteLayers[z][0] = (byte)smallestID; //This byte indicates which technique the decompressor should use, and should be before the image data
Array.Copy(compressionTechniques[smallestID], 0, byteLayers[z], 1, compressionTechniques[smallestID].Length);
});
//Combine all byte layers by looping trough all of them and adding them after each other
List <byte> output = new List <byte>();
foreach (byte[] b in byteLayers)
{
output.AddRange(b);
}
//Return the data of all the color channels combined
return(output.ToArray());
}
