typedef unsigned __int16 uint16_t; typedef unsigned unsigned char uint8_t; int stretch_percent_16to8(const char *inFilename, const char *dstFilename) { GDALAllRegister(); //为了支持中文路径 CPLSetConfigOption("GDAL_FILENAME_IS_UTF8", "NO"); int src_height = 0; int src_width = 0; GDALDataset *poIn = (GDALDataset *)GDALOpen(inFilename, GA_ReadOnly); //打开影像 //获取影像大小 src_width = poIn->GetRasterXSize(); src_height = poIn->GetRasterYSize(); //获取影像波段数 int InBands = poIn->GetRasterCount(); //获取影像格式 GDALDataType eDataType = poIn->GetRasterBand(1)->GetRasterDataType(); //定义存储影像的空间参考数组 double adfInGeoTransform[6] = { 0 }; const char *pszWKT = NULL; //获取影像空间参考 poIn->GetGeoTransform(adfInGeoTransform); pszWKT = poIn->GetProjectionRef(); //创建文件 GDALDriver *poDriver = (GDALDriver *)GDALGetDriverByName("GTiff"); GDALDataset *poOutputDS = poDriver->Create(dstFilename, src_width, src_height, InBands, GDT_Byte, NULL); //设置拉伸后图像的空间参考以及地理坐标 poOutputDS->SetGeoTransform(adfInGeoTransform); poOutputDS->SetProjection(pszWKT); //读取影像 cout << "16位影像降到8位影像处理..." << endl; for (int iBand = 0; iBand < InBands; iBand++) { cout << "正在处理第 " << iBand + 1 << " 波段" << endl; //读取影像 uint16_t *srcData = (uint16_t *)malloc(sizeof(uint16_t) *src_width * src_height * 1); memset(srcData, 0, sizeof(uint16_t) * 1 * src_width * src_height); int src_max = 0, src_min = 65500; //读取多光谱影像到缓存 poIn->GetRasterBand(iBand + 1)->RasterIO(GF_Read, 0, 0, src_width, src_height, srcData + 0 * src_width * src_height, src_width, src_height, GDT_UInt16, 0, 0); //} //统计最大值 for (int src_row = 0; src_row < src_height; src_row++) { for (int src_col = 0; src_col < src_width; src_col++) { uint16_t src_temVal = *(srcData + src_row * src_width + src_col); if (src_temVal > src_max) src_max = src_temVal; if (src_temVal < src_min) src_min = src_temVal; } } double *numb_pix = (double *)malloc(sizeof(double)*(src_max + 1)); //存像素值直方图，即每个像素值的个数 memset(numb_pix, 0, sizeof(double) * (src_max + 1)); // ------- 统计像素值直方图 ------------ // for (int src_row = 0; src_row < src_height; src_row++) { for (int src_col = 0; src_col < src_width; src_col++) { uint16_t src_temVal = *(srcData + src_row * src_width + src_col); *(numb_pix + src_temVal) += 1; } } double *frequency_val = (double *)malloc(sizeof(double)*(src_max + 1)); //像素值出现的频率 memset(frequency_val, 0.0, sizeof(double)*(src_max + 1)); for (int val_i = 0; val_i <= src_max; val_i++) { *(frequency_val + val_i) = *(numb_pix + val_i) / double(src_width * src_height); } double *accumlt_frequency_val = (double*)malloc(sizeof(double)*(src_max + 1)); //像素出现的累计频率 memset(accumlt_frequency_val, 0.0, sizeof(double)*(src_max + 1)); for (int val_i = 0; val_i <= src_max; val_i++) { for (int val_j = 0; val_j < val_i; val_j++) { *(accumlt_frequency_val + val_i) += *(frequency_val + val_j); } } //统计像素两端截断值 int minVal = 0, maxVal = 0; for (int val_i = 1; val_i < src_max; val_i++) { double acc_fre_temVal0 = *(frequency_val + 0); double acc_fre_temVal = *(accumlt_frequency_val + val_i); if ((acc_fre_temVal - acc_fre_temVal0) > 0.0015) { minVal = val_i; break; } } for (int val_i = src_max - 1; val_i > 0; val_i--) { double acc_fre_temVal0 = *(accumlt_frequency_val + src_max); double acc_fre_temVal = *(accumlt_frequency_val + val_i); if (acc_fre_temVal < (acc_fre_temVal0 - 0.00012)) { maxVal = val_i; break; } } for (int src_row = 0; src_row < src_height; src_row++) { uint8_t *dstData = (uint8_t*)malloc(sizeof(uint8_t)*src_width); memset(dstData, 0, sizeof(uint8_t)*src_width); for (int src_col = 0; src_col < src_width; src_col++) { uint16_t src_temVal = *(srcData + src_row * src_width + src_col); double stre_temVal = (src_temVal - minVal) / double(maxVal - minVal); if (src_temVal < minVal) { *(dstData + src_col) = (src_temVal)*(20.0 / double(minVal)); } else if (src_temVal > maxVal) { stre_temVal = (src_temVal - src_min) / double(src_max - src_min); *(dstData + src_col) = 254; } else *(dstData + src_col) = pow(stre_temVal, 0.7) * 250; } poOutputDS->GetRasterBand(iBand + 1)->RasterIO(GF_Write, 0, src_row, src_width, 1, dstData, src_width, 1, GDT_Byte, 0, 0); free(dstData); } free(numb_pix); free(frequency_val); free(accumlt_frequency_val); free(srcData); } 来源：51CTO
作者：似曾相识_燕归来
链接：https://blog.csdn.net/u010624166/article/details/101108089