public class TIFF
{byte[] data;//把TIFF文件读到byte数组中//接下来是TIFF文件的各种属性
bool ByteOrder;//true:II  false:MM
public int ImageWidth = 0;
public int ImageLength = 0;
public List<int> BitsPerSample = new List<int>();
public int PixelBytes = 0;
public int Compression = 0;
public int PhotometricInterpretation = 0;
public List<int> StripOffsets = new List<int>();
public int RowsPerStrip = 0;
public List<int> StripByteCounts = new List<int>();
public float XResolution = 0f;
public float YResolution = 0f;
public int ResolutionUnit = 0;
public int Predictor = 0;
public List<int> SampleFormat = new List<int>();
public string DateTime = "";
public string Software = "";public void Decode(string path){//...
}
private int DecodeIFH(){//...
}
public int DecodeIFD(int Pos){//...
}
private void DecodeDE(int Pos){//...
}
private void GetDEValue(int TagIndex, int TypeIndex, int Count, byte[] val){//...
}
private void DecodeStrips(){//...
}
static private DType[] TypeArray = {//...
};
struct DType
{public DType(string n, int s){   //...}public string name;public int size;
}

public void Decode(string path){data = File.ReadAllBytes(path);//首先解码文件头，获得编码方式是大端还是小端，以及第一个IFD的位置int pIFD = DecodeIFH();//然后解码第一个IFD，返回值是下一个IFD的地址while (pIFD != 0){pIFD = DecodeIFD(pIFD);}}

private int DecodeIFH(){string byteOrder = GetString(0,2);if (byteOrder == "II")ByteOrder = true;else if (byteOrder == "MM")ByteOrder = false;elsethrow new UnityException("The order value is not II or MM.");int Version = GetInt(2, 2);if (Version != 42)throw new UnityException("Not TIFF.");return GetInt(4, 4);}

private int GetInt(int startPos, int Length){int value = 0;if (ByteOrder)// "II")for (int i = 0; i < Length; i++) value |= data[startPos + i] << i * 8;else // "MM")for (int i = 0; i < Length; i++) value |= data[startPos + Length - 1 - i] << i * 8;return value;}private float GetRational(int startPos){int A = GetInt(startPos,4);int B = GetInt(startPos+4,4);return A / B;}private float GetFloat(byte[] b, int startPos){byte[] byteTemp;if (ByteOrder)// "II")byteTemp =new byte[]{b[startPos],b[startPos+1],b[startPos+2],b[startPos+3]};elsebyteTemp =new byte[]{b[startPos+3],b[startPos+2],b[startPos+1],b[startPos]};float fTemp = BitConverter.ToSingle(byteTemp,0);return fTemp;}private string GetString(int startPos, int Length)//II和MM对String没有影响{string tmp = "";for (int i = 0; i < Length; i++)tmp += (char)data[startPos];return tmp;}

public int DecodeIFD(int Pos){int n = Pos;int DECount = GetInt(n, 2);n += 2;for (int i = 0; i < DECount; i++){DecodeDE(n);n += 12;}//已获得每条扫描线位置，大小，压缩方式和数据类型，接下来进行解码DecodeStrips();int pNext = GetInt(n, 4);return pNext;}

public void DecodeDE(int Pos){int TagIndex = GetInt(Pos, 2);int TypeIndex = GetInt(Pos + 2, 2);int Count = GetInt(Pos + 4, 4);//Debug.Log("Tag: " + Tag(TagIndex) + " DataType: " + TypeArray[TypeIndex].name + " Count: " + Count);//先把找到数据的位置int pData = Pos + 8;int totalSize = TypeArray[TypeIndex].size * Count;if (totalSize > 4)pData = GetInt(pData, 4);//再根据Tag把值读出并存起来GetDEValue(TagIndex, TypeIndex, Count, pData);}

struct DType
{public DType(string n, int s){name = n;size = s;}public string name;public int size;
}
static private DType[] TypeArray = {new DType("???",0),new DType("byte",1), //8-bit unsigned integernew DType("ascii",1),//8-bit byte that contains a 7-bit ASCII code; the last byte must be NUL (binary zero)new DType("short",2),//16-bit (2-byte) unsigned integer.new DType("long",4),//32-bit (4-byte) unsigned integer.new DType("rational",8),//Two LONGs: the first represents the numerator of a fraction; the second, the denominator.new DType("sbyte",1),//An 8-bit signed (twos-complement) integernew DType("undefined",1),//An 8-bit byte that may contain anything, depending on the definition of the fieldnew DType("sshort",1),//A 16-bit (2-byte) signed (twos-complement) integer.new DType("slong",1),// A 32-bit (4-byte) signed (twos-complement) integer.new DType("srational",1),//Two SLONG’s: the first represents the numerator of a fraction, the second the denominator.new DType("float",4),//Single precision (4-byte) IEEE formatnew DType("double",8)//Double precision (8-byte) IEEE format};

//先把找到数据的位置
int pData = Pos + 8;
int totalSize = TypeArray[TypeIndex].size * Count;
if (totalSize > 4)pData = GetInt(pData, 4);

private void GetDEValue(int TagIndex, int TypeIndex, int Count, int pdata){int typesize = TypeArray[TypeIndex].size;switch (TagIndex){case 254: break;//NewSubfileTypecase 255: break;//SubfileTypecase 256://ImageWidthImageWidth = GetInt(pdata,typesize);break;case 257://ImageLengthif (TypeIndex == 3)//shortImageLength = GetInt(pdata,typesize);break;case 258://BitsPerSamplefor (int i = 0; i < Count; i++){int v = GetInt(pdata+i*typesize,typesize);BitsPerSample.Add(v);PixelBytes += v/8;}break;case 259: //CompressionCompression = GetInt(pdata,typesize);break;case 262: //PhotometricInterpretationPhotometricInterpretation = GetInt(pdata,typesize);break;case 273://StripOffsetsfor (int i = 0; i < Count; i++){int v = GetInt(pdata+i*typesize,typesize);StripOffsets.Add(v);}break;case 274: break;//Orientationcase 277: break;//SamplesPerPixelcase 278://RowsPerStripRowsPerStrip = GetInt(pdata,typesize);break;case 279://StripByteCountsfor (int i = 0; i < Count; i++){int v = GetInt(pdata+i*typesize,typesize);StripByteCounts.Add(v);}break;case 282: //XResolutionXResolution = GetRational(pdata); break;case 283://YResolutionYResolution = GetRational(pdata); break;case 284: break;//PlanarConfigcase 296://ResolutionUnitResolutionUnit = GetInt(pdata,typesize);break;case 305://SoftwareSoftware = GetString(pdata,typesize); break;case 306://DateTimeDateTime = GetString(pdata,typesize); break;case 315: break;//Artistcase 317: //Differencing PredictorPredictor = GetInt(pdata,typesize);break;case 320: break;//ColorDistributionTablecase 338: break;//ExtraSamplescase 339: //SampleFormatfor (int i = 0; i < Count; i++){int v = GetInt(pdata+i*typesize,typesize);SampleFormat.Add(v);} break;default: break;}}

private void DecodeStrips(){int pStrip = 0;int size = 0;tex = new Texture2D(ImageWidth,ImageLength,TextureFormat.RGBA32,false);Color[] colors = new Color[ImageWidth*ImageLength];if (Compression == 5){int stripLength = ImageWidth * RowsPerStrip * BitsPerSample.Count * BitsPerSample[1] / 8;CompressionLZW.CreateBuffer(stripLength);if(Predictor==1){int index = 0;for (int y = 0; y < StripOffsets.Count; y++){pStrip = StripOffsets[y];//起始位置size = StripByteCounts[y];//读取长度byte[] Dval = CompressionLZW.Decode(data, pStrip, size);for(int x = 0;x<ImageWidth;x++){float R = GetFloat(Dval, x * PixelBytes   );float G = GetFloat(Dval, x * PixelBytes+4 );float B = GetFloat(Dval, x * PixelBytes+8 );float A = GetFloat(Dval, x * PixelBytes+12);colors[index++] = new Color(R,G,B,A);}}} else{}}tex.SetPixels(colors);tex.Apply();}

while ((Code = GetNextCode()) != EoiCode) {if (Code == ClearCode) {InitializeTable();Code = GetNextCode();if (Code == EoiCode)break;WriteString(StringFromCode(Code));OldCode = Code;} /* end of ClearCode case */else {if (IsInTable(Code)) {WriteString(StringFromCode(Code));AddStringToTable(StringFromCode(OldCode)+FirstChar(StringFromCode(Code)));OldCode = Code;} else {OutString = StringFromCode(OldCode) +FirstChar(StringFromCode(OldCode));WriteString(OutString);AddStringToTable(OutString);OldCode = Code;}} /* end of not-ClearCode case */
} /* end of while loop */

public class CompressionLZW
{static private int Code = 0;static private int EoiCode = 257;static private int ClearCode = 256;static private int OldCode = 256;static private string[] Dic= new string[4096];static private int DicIndex;static private byte[] Input;static private int startPos;static private byte[] Output;static private int resIndex;static private int current=0;static private int bitsCount = 0;static string combine ="{0}{1}";static private void ResetPara(){OldCode = 256;DicIndex = 0;current = 0;resIndex = 0;}static public void CreateBuffer(int size){//...}static public byte[] Decode(byte[] input,int _startPos,int _readLength){//...}static private int GetNextCode(){//...}static private int GetBit(int x){//...}static private int GetStep(){//...}static private void InitializeTable(){//...}static private void WriteResult(string code){//...}
}

static public byte[] Decode(byte[] input,int _startPos,int _readLength){Input = input;startPos = _startPos;bitsCount = _readLength*8;ResetPara();while ((Code = GetNextCode()) != EoiCode) {if (Code == ClearCode) {InitializeTable();Code = GetNextCode();if (Code == EoiCode)break;WriteResult(Dic[Code]);OldCode = Code;}else {if (Dic[Code]!=null) {WriteResult(Dic[Code]);Dic[DicIndex++] =string.Format(combine, Dic[OldCode],Dic[Code][0]);OldCode = Code;} else {   string outs = string.Format(combine, Dic[OldCode], Dic[OldCode][0]);WriteResult(outs);Dic[DicIndex++] =outs;OldCode = Code;}}}return Output;}

static private int GetNextCode()
{int tmp = 0;int step = GetStep();if (current + step > bitsCount)return EoiCode;for (int i = 0; i<step; i++){int x = current + i;int bit = GetBit(x)<<(step-1-i);tmp+=bit;}current += step;//一开始读9个bit//读到510的时候，下一个开始读10bit//读到1022的时候，下一个开始读11bit//读到2046的时候，下一个开始读11bitreturn tmp;
}
static private int GetStep()
{int res = 12;int tmp = DicIndex-2047;//如果大于2046.则为正或零res+=(tmp>>31);tmp = DicIndex-1023;res+=(tmp>>31);tmp = DicIndex-511;res+=(tmp>>31);return res;
}
static private int GetBit(int x)
{int byteIndex = x/8; //该bit在第几个byte里int bitIndex =7-x+byteIndex*8;//该bit是这个byte的第几位byte b = Input[startPos + byteIndex];return (b>>bitIndex)&1;
}

int bitIndex =7-x+byteIndex*8;//该bit是这个byte的第几位