请高手帮我看一下这个头文件这么回事？

<P> L=DN*gain +bias<BR>求出各样点的辐射能量值。其中L为地物在大气顶部的辐射能量值，单位为；DN为样本的灰度均值，gain和bias分别为图像的增益与偏置，可从图像的头文件中读取。<BR>头文件：</P>
<P><BR>CORRECTION_METHOD_GAIN_BAND1 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND2 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND3 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND4 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND5 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND61 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND62 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND7 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND8 = "CPF"<BR>   CORRECTION_METHOD_BIAS = "IC"<BR>   BAND1_GAIN = "H"<BR>   BAND2_GAIN = "H"<BR>   BAND3_GAIN = "H"<BR>   BAND4_GAIN = "L"<BR>   BAND5_GAIN = "H"<BR>   BAND6_GAIN1 = "L"<BR>   BAND6_GAIN2 = "H"<BR>   BAND7_GAIN = "H"<BR>   BAND8_GAIN = "L"<BR>   BAND1_GAIN_CHANGE = "0"<BR>   BAND2_GAIN_CHANGE = "0"<BR>   BAND3_GAIN_CHANGE = "0"<BR>   BAND4_GAIN_CHANGE = "0"<BR>   BAND5_GAIN_CHANGE = "0"<BR>   BAND6_GAIN_CHANGE1 = "0"<BR>   BAND6_GAIN_CHANGE2 = "0"<BR>   BAND7_GAIN_CHANGE = "0"<BR>   BAND8_GAIN_CHANGE = "0"<BR>   BAND1_SL_GAIN_CHANGE = "0"<BR>   BAND2_SL_GAIN_CHANGE = "0"<BR>   BAND3_SL_GAIN_CHANGE = "0"<BR>   BAND4_SL_GAIN_CHANGE = "0"<BR>   BAND5_SL_GAIN_CHANGE = "0"<BR>   BAND6_SL_GAIN_CHANGE1 = "0"<BR>   BAND6_SL_GAIN_CHANGE2 = "0"<BR>   BAND7_SL_GAIN_CHANGE = "0"<BR>   BAND8_SL_GAIN_CHANGE = "0"</P>
<P>请问gain值是什么？</P>

这个数据是Geotiff的吧？没有增益和偏置

在哪能得到头文件呢,头文件一般是什么格式?

<P><a href="http://ltpwww.gsfc.nasa.gov/IAS/handbook/pdfs/L5TMLUTIEEE2003.pdf#search=%22Revised%20Landsat-5%20TM%20Radiometric%20Calibration%20Procedures%20and%20Postcalibration%20Dynamic%20Ranges%22" target="_blank" >http://ltpwww.gsfc.nasa.gov/IAS/handbook/pdfs/L5TMLUTIEEE2003.pdf#search=%22Revised%20Landsat-5%20TM%20Radiometric%20Calibration%20Procedures%20and%20Postcalibration%20Dynamic%20Ranges%22</A></P>

<P>看看这篇文章！</P>