Introduction - If you have any usage issues, please Google them yourself
TIFFGetField(pTif, TIFFTAG_TILEWIDTH, &nTileWidth)
TIFFGetField(pTif, TIFFTAG_TILELENGTH, &nTileHeight)
//计算块数
int nHTileCount = (nWidth+ nTileWidth-1)/nTileWidth
int nVTileCount = (nHeight+ nTileHeight-1)/nTileHeight