从base64编码的字符串分离图像和文本

Question

我正在编写一个接收base64编码的字符串将其解析为数据库的ASP.NET中的API。我的问题如下：这些字符串包含一个图像和一些后面的文本，我无法找到一种方法来分离它们，然后处理他的文本部分。当然，我不可能改变格式。所以我想知道如果有人有一个想法或工具来检测图像和文字部分的开始和结束？

这里有一个例子：

HShIBgAwMEFCQ0QAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABs9ARtAHWH_G1IAG00AG1QAHVC0tB0oSgIAAQEdKEoCAAIBHShKAgADARtwADL_G2EBHVza_x0oTPoPMHAwAQExQAFmAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAf_AAAAAAAf4AAAAAAAAAAAAAAAAAAAAAAAB______-D___8AAAAAB___AAAAAB__8AAAAAAAAAAAAAAAAAAAAAAAf______g_____gAAAB___-AAAAD___wAAD_8AAAf_gAAAAAAAAAAAH______4P_____AAAB____4AAAD____AAA__AAAH_4AAAAAAAAAAAB______-D_____8AAB_____AAAD____8AAP_4AAB_-AAAAAAAAAAAAf______g______wAA_____4AAB_____gAD__AAAf_gAAAAAAAAAAAH______4P_____-AAf_____gAA_____8AA__wAAH_4AAAAAAAAAAAB______-D______wAP_____4AAf_____wAP_-AAB_-AAAAAAAAAAAAf______g______-AD______AAP_____8AD__gAAf_gAAAAAAAAAAAH______4P______wB______4AH______gA__8AAH_4AAAAAAAAAAAB______-D______-A__4AP_-AD__8D__8AP__gAB_-AAAAAAAAAAAAf_gAAAAA__AAf__wP_4AA__wA__4AH__gD__4AAf_gAAAAAAAAAAAH_4AAAAAP_wAAf_8D_8AAH_8Af_4AAf_4A___AAH_4AAAAAAAAAAAB_-AAAAAD_8AAB__g_-AAA__AP_8AAD__AP__wAB_-AAAAAAAAAAAAf_gAAAAA__AAAP_4f_gAAP_wD_-AAAf_wD__-AAf_gAAAAAAAAAAAH_4AAAAAP_wAAB_-H_4AAB_-A__AAAD_-A___wAH_4AAAAAAAAAAAB_-AAAAAD_8AAAf_h_-AAAf_gf_wAAAf_gP__8AB_-AAAAAAAAAAAAf_gAAAAA__AAAD_4f_gAAH_4H_4AAAH_4D___gAf_gAAAAAAAAAAAH_4AAAAAP_wAAA__H_8AAAAAD_-AAAA__A___4AH_4AAAAAAAAAAAB_-AAAAAD_8AAAP_w__AAAAAA__AAAAP_wP___AB_-AAAAAAAAAAAAf_gAAAAA__AAAD_8P_8AAAAAP_wAAAD_8D_7_4Af_gAAAAAAAAAAAH_4AAAAAP_wAAA__D__wAAAAD_8AAAAf_A_-_-AH_4AAAAAAAAAAAB_-AAAAAD_8AAAP_w___wAAAA_-AAAAH_4P_v_wB_-AAAAAAAAAAAAf_____4A__AAAD_8H___gAAAf_gAAAB_-D_5_8Af_gAAAAAAAAAAAH______gP_wAAA_-B____gAAH_4AAAAf_g_-f_gH_4AAAAAAAAAAAB______4D_8AAAf_gP____gAB_-AAAAH_4P_j_8B_-AAAAAAAAAAAAf_____-A__AAAP_4B_____AAf_gAAAA_-D_4__Af_gAAAAAAAAAAAH______gP_wAAH_-AP____8AH_4AAAAP_g_-H_4H_4AAAAAAAAAAAB______4D_8AAD__AB_____wB_-AAAAD_4P_h_-B_-AAAAAAAAAAAAf_____-A__AAD__wAH____-Af_AAAAA_-D_4P_wf_gAAAAAAAAAAAH______gP_4Af__4AAf____wH_wAAAAP_h_-D_8H_4AAAAAAAAAAAB______4D______-AAA____-B_-AAAAD_4f_gf_h_-AAAAAAAAAAAAf_____-A_______AAAB____wf_gAAAA_-D_4H_4f_AAAAAAAAAAAAH_4AAAAAP______gAAAB___-H_4AAAAP_h_-A__H_wAAAAAAAAAAAB_-AAAAAD______wAAAAB___h_-AAAAH_4P_gH_x_8AAAAAAAAAAAAf_gAAAAA______4AAAAAD__8f_gAAAB_-H_4B_-f_AAAAAAAAAAAAH_4AAAAAP_____8AAAAAAP__H_4AAAAf_h_-AP_n_wAAAAAAAAAAAB_-AAAAAD_____8AAAAAAA__w_-AAAAH_4f_gD_9_8AAAAAAAAAAAAf_gAAAAA_____8AAAAAAAH_8P_wAAAD_8D_4Af_f_AAAAAAAAAAAAH_4AAAAAP____4AAf_gAAA__D_8AAAA__B_-AD_7_wAAAAAAAAAAAB_-AAAAAD_8AAAAAH_4AAAH_w__AAAAP_wf_gA_-_8AAAAAAAAAAAAf_gAAAAA_-AAAAAB_-AAAB_8H_4AAAH_8H_4AH___AAAAAAAAAAAAH_4AAAAAP_gAAAAAP_gAAAf_B_-AAAB_-A_-AB___wAAAAAAAAAAAB_-AAAAAD_4AAAAAD_8AAAH_wf_wAAA__gf_gAP__8AAAAAAAAAAAAf_gAAAAA_-AAAAAA__AAAB_8D_-AAAP_wH_4AB___AAAAAAAAAAAAH_4AAAAAP_gAAAAAP_4AAA__A__wAAH_8B_-AAf__wAAAAAAAAAAAB_-AAAAAD_4AAAAAB__AAAf_wH_-AAD_-Af_gAD__8AAAAAAAAAAAAf______g_-AAAAAAf_8AAP_4B__wAD__gH_4AA___AAAAAAAAAAAAH______4P_gAAAAAH__wAf_-AP__AD__wB_-AAH__wAAAAAAAAAAAB______-D_4AAAAAA_______AB______8Af_gAA__8AAAAAAAAAAAAf______g_-AAAAAAH______wAf_____-AH_4AAP__AAAAAAAAAAAAH______4P_gAAAAAA______4AD______AB_-AAB__wAAAAAAAAAAAB______-D_4AAAAAAH_____8AAf_____gAf_gAAf_8AAAAAAAAAAAAf______g_-AAAAAAA_____-AAD_____wAH_4AAD__AAAAAAAAAAAAH______4P_gAAAAAAH_____AAAP____4AB_-AAA__wAAAAAAAAAAAB______-D_4AAAAAAAf____AAAB____4AAP_gAAH_8AAAAAAAAAAAAf______g_-AAAAAAAB____AAAAH___4AAD_4AAA__AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD__-AAAAAf__4AAA_-AAAP_wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH_0AAAAAA__gAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAf_HAQD4AgEIEgIAAAAAAgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH_x4OD_gf_D_8P_AB4Dh_gOA4f-ABwHHA_AcA_AAAAAAAAAAAAAAAB_8OHh98H_w__D_4AOBw_8DgOH_wAcBxwf8HA_4DgMAAAAAAAAAAAAcADxw8HhwAOAAwPADwceHg4DhweAHAccPHhwfPA8DAAAAAAAAAAAAHAAc4OA4cADgAOBwAcOHAcOA4YDgA4OHDg4cHA4PgwAAAAAAAAAAABwAD8DAAHAA4ADgOADnDgHDgOGA4AODhwwOHDgHD4MAAAAAAAAAAAAcAAfBwABwAOAA4DgA5w4Aw4DhgOADgwcOABw4Bw3DAAAAAAB0oTAIAMDIdXCYAHShM-gUwcDABATFAASYAAAAAAAf_AeBwAB_8P_g4DgAfg4Aw4DjgeABxwcPwBwwBwzDAAAAAAAAAAAAH_wHgcAAf_D_4OA4AHwOAOOA4__AAccHB_gccAcM4wAAAAAAAAAAABwAD8HAAHAA4ADgOAA8DgDjgOP_gAHGBwD8HHAHDHMAAAAAAAAAAAAcAA_gwDhwAOAA4DgAGA4Aw4DjgcAA7gcAHhwwBwxzAAAAAAAAAAAAHAAc4OA4cADgAOA4ADgOAcOA44DgAO4HEAccOAcMOwAAAAAAAAAAABwAOHDgOHAA4ADgcAA4DgHDgcOA4ADsBxwHHDgHDB8AAAAAAAAAAAAf_Dh4ePBwAOAA4PAAOAcDg4HDgOAAfAccBxw8DgwfAAAAAAAAAAAAH_xwOD_gf_D_8P_gADgD_4H_g4DgAHwHDx4cHh4MDwAAAAAAAAAAAB_84BwfwH_w__D_gAA4Af4A_wGA4AA4Bwf8HA_8DA8AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAB4AD4BgGAAOAcD-BwD8AwHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAdKEwCADAyG3QACht0AEVQU09OIEVVUk9QRSBTSE9QG3QACht0AE90dG8tSGFobiA0G3QACht0AE1lZXJidXNjaBt0AAobdAA0OSA1NTUgNTg0IDExOTUbdAAKCht0AFRoYW5rIHlvdSBmb3Igc2hvcHBpbmcbdAAKG3QAUGxlYXNlIHZpc2l0IHVzIGFnYWluIHNvb24bdAAKCht0ADIwMTUvMTAvMzAgMTg6MTkbdAAKG3QACht0AEVQU09OIFdvcmtGb3JjZSBXUC00G3QAICAxG3QAIBt0ACAgICAgICAgIBt0EIAyNjIbdBAKCh0hEBt0EE5FVB0hABt0ECAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIIAyNTAbdBAKHSEQG3QQVEFYHSEAG3QQICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIIAxMht0EAodIRAbdBBUT1RBTBt0ECAgICAgICAgICAggDI2Mh0hABt0EAoKG3QQQ0FTSBt0ECAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICCAMzAwG3QQCh0hEBt0EENIQU5HRRt0ECAgICAgICAgICAggDM4HSEAG3QQCgobYQEbZAMdVkIA 

Answer 1

我不能评论，所以我张贴此作为一个答案：

你可以编码字符串解码的base64二进制，并尝试检测图像的magic number （假设它有一个）。如果它是JPEG图像，则它具有开始和结束签名。一个BMP具有编码到标题中的图像的大小。