为现有图像处理程序添加读写exif的功能
Posted GreenOpen专注图像处理
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了为现有图像处理程序添加读写exif的功能相关的知识，希望对你有一定的参考价值。
为现有图像处理程序添加读取exif的功能
exif是图片的重要参数，在使用过程中很关键的一点是exif的数据能够和图片一起存在。exif的相关功能在操作系统中就集成了，在csharp中也似乎有了实现。但是使用mfc来实现这个功能，的确费了我的一些时间。下面是我的实现方式。
读取exif,参考了网络资料
添加cexif.h和cexif.cpp，添加入现有程序
在需要读取的地方添加相关代码
FILE* hFile=fopen(FilePathName.c_str(),"rb");
if (hFile){
memset(&m_exifinfo,0,sizeof(EXIFINFO));
Cexif exif(&m_exifinfo);
exif.DecodeExif(hFile);
fclose(hFile);
if (m_exifinfo.IsExif)
{
string cameramaker = m_exifinfo.CopyRight;//获得CopyRight
vector<string> vecParams;
if ("@@" == cameramaker.substr(0,2)) //确认为带参数图片
{
cameramaker = cameramaker.substr(2,cameramaker.length()-2);
SplitString(cameramaker,vecParams,"|");//保存各参数到vecParams中去
//updateGuides给的是图像真实像素值
if (vecParams.size()<13)
return;
m_freal2screen = Str2RealPixF(vecParams[12]);//获得之前保存的比值
if (m_freal2screen<0)
return;
UpdateGuides(Str2RealPix(vecParams[0]),Str2RealPix(vecParams[1]),Str2RealPix(vecParams[2]),Str2RealPix(vecParams[3]),Str2RealPix(vecParams[4]),Str2RealPix(vecParams[5]),Str2RealPix(vecParams[6]),Str2RealPix(vecParams[7]),Str2RealPix(vecParams[8]),Str2RealPix(vecParams[9]),Str2RealPix(vecParams[10]),Str2RealPix(vecParams[11]));
}
}
else
MessageBox("没有找到矢量数据信息！","EXIF",MB_OK);
}
fclose(hFile);
但是这里的exif读取的信息不实很全
同时找到另一个代码,但是版本比较老，只能在vc6下面运行
这个时候，我需要考虑的就是写入的数据是否够长的问题。我进行了边界测试
经过测试，在这种模式下是没有问题的
对原有代码进行初步修改就可以。考虑到还是现有集成的比较好用，还是用集成好的。但是集成好的版本没有 版权这个段？这个如何办了？
反思一想，问题不就出现在位置信息吗？我将正确的版权信息覆盖掉make信息，问题解决。
最后提供我修改完成的带版权信息的exif.c。
解决问题的思路很重要。
附全部代码
/* * File: exif.cpp * Purpose: cpp EXIF reader * 16/Mar/2003 <ing.davide.pizzolato@libero.it> * based on jhead-1.8 by Matthias Wandel <mwandel(at)rim(dot)net> */ #include "stdafx.h" #include "Exif.h" //////////////////////////////////////////////////////////////////////////////// Cexif::Cexif(EXIFINFO* info) { if (info) { m_exifinfo = info; freeinfo = false; } else { m_exifinfo = new EXIFINFO; memset(m_exifinfo,0,sizeof(EXIFINFO)); freeinfo = true; } m_szLastError[0]=\'\\0\'; ExifImageWidth = MotorolaOrder = 0; SectionsRead=0; memset(&Sections, 0, MAX_SECTIONS * sizeof(Section_t)); } //////////////////////////////////////////////////////////////////////////////// Cexif::~Cexif() { for(int i=0;i<MAX_SECTIONS;i++) if(Sections[i].Data) free(Sections[i].Data); if (freeinfo) delete m_exifinfo; } //////////////////////////////////////////////////////////////////////////////// bool Cexif::DecodeExif(FILE * hFile) { int a; int HaveCom = 0; a = fgetc(hFile); if (a != 0xff || fgetc(hFile) != M_SOI){ return 0; } for(;;){ int itemlen; int marker = 0; int ll,lh, got; unsigned char * Data; if (SectionsRead >= MAX_SECTIONS){ strcpy(m_szLastError,"Too many sections in jpg file"); return 0; } for (a=0;a<7;a++){ marker = fgetc(hFile); if (marker != 0xff) break; if (a >= 6){ printf("too many padding unsigned chars\\n"); return 0; } } if (marker == 0xff){ // 0xff is legal padding, but if we get that many, something\'s wrong. strcpy(m_szLastError,"too many padding unsigned chars!"); return 0; } Sections[SectionsRead].Type = marker; // Read the length of the section. lh = fgetc(hFile); ll = fgetc(hFile); itemlen = (lh << 8) | ll; if (itemlen < 2){ strcpy(m_szLastError,"invalid marker"); return 0; } Sections[SectionsRead].Size = itemlen; Data = (unsigned char *)malloc(itemlen); if (Data == NULL){ strcpy(m_szLastError,"Could not allocate memory"); return 0; } Sections[SectionsRead].Data = Data; // Store first two pre-read unsigned chars. Data[0] = (unsigned char)lh; Data[1] = (unsigned char)ll; got = fread(Data+2, 1, itemlen-2,hFile); // Read the whole section. if (got != itemlen-2){ strcpy(m_szLastError,"Premature end of file?"); return 0; } SectionsRead += 1; switch(marker){ case M_SOS: // stop before hitting compressed data // If reading entire image is requested, read the rest of the data. /*if (ReadMode & READ_IMAGE){ int cp, ep, size; // Determine how much file is left. cp = ftell(infile); fseek(infile, 0, SEEK_END); ep = ftell(infile); fseek(infile, cp, SEEK_SET); size = ep-cp; Data = (uchar *)malloc(size); if (Data == NULL){ strcpy(m_szLastError,"could not allocate data for entire image"); return 0; } got = fread(Data, 1, size, infile); if (got != size){ strcpy(m_szLastError,"could not read the rest of the image"); return 0; } Sections[SectionsRead].Data = Data; Sections[SectionsRead].Size = size; Sections[SectionsRead].Type = PSEUDO_IMAGE_MARKER; SectionsRead ++; HaveAll = 1; }*/ return 1; case M_EOI: // in case it\'s a tables-only JPEG stream printf("No image in jpeg!\\n"); return 0; case M_COM: // Comment section if (HaveCom){ // Discard this section. free(Sections[--SectionsRead].Data); Sections[SectionsRead].Data=0; }else{ process_COM(Data, itemlen); HaveCom = 1; } break; case M_JFIF: // Regular jpegs always have this tag, exif images have the exif // marker instead, althogh ACDsee will write images with both markers. // this program will re-create this marker on absence of exif marker. // hence no need to keep the copy from the file. free(Sections[--SectionsRead].Data); Sections[SectionsRead].Data=0; break; case M_EXIF: // Seen files from some \'U-lead\' software with Vivitar scanner // that uses marker 31 for non exif stuff. Thus make sure // it says \'Exif\' in the section before treating it as exif. if (memcmp(Data+2, "Exif", 4) == 0){ m_exifinfo->IsExif = process_EXIF((unsigned char *)Data+2, itemlen); }else{ // Discard this section. free(Sections[--SectionsRead].Data); Sections[SectionsRead].Data=0; } break; case M_SOF0: case M_SOF1: case M_SOF2: case M_SOF3: case M_SOF5: case M_SOF6: case M_SOF7: case M_SOF9: case M_SOF10: case M_SOF11: case M_SOF13: case M_SOF14: case M_SOF15: process_SOFn(Data, marker); break; default: // Skip any other sections. //if (ShowTags) printf("Jpeg section marker 0x%02x size %d\\n",marker, itemlen); break; } } return 1; } //////////////////////////////////////////////////////////////////////////////// /*-------------------------------------------------------------------------- Process a EXIF marker Describes all the drivel that most digital cameras include... --------------------------------------------------------------------------*/ bool Cexif::process_EXIF(unsigned char * CharBuf, unsigned int length) { m_exifinfo->FlashUsed = 0; /* If it\'s from a digicam, and it used flash, it says so. */ m_exifinfo->Comments[0] = \'\\0\'; /* Initial value - null string */ ExifImageWidth = 0; { /* Check the EXIF header component */ static const unsigned char ExifHeader[] = "Exif\\0\\0"; if (memcmp(CharBuf+0, ExifHeader,6)){ strcpy(m_szLastError,"Incorrect Exif header"); return 0; } } if (memcmp(CharBuf+6,"II",2) == 0){ MotorolaOrder = 0; }else{ if (memcmp(CharBuf+6,"MM",2) == 0){ MotorolaOrder = 1; }else{ strcpy(m_szLastError,"Invalid Exif alignment marker."); return 0; } } /* Check the next two values for correctness. */ if (Get16u(CharBuf+8) != 0x2a){ strcpy(m_szLastError,"Invalid Exif start (1)"); return 0; } int FirstOffset = Get32u(CharBuf+10); if (FirstOffset < 8 || FirstOffset > 16){ // I used to ensure this was set to 8 (website I used indicated its 8) // but PENTAX Optio 230 has it set differently, and uses it as offset. (Sept 11 2002) strcpy(m_szLastError,"Suspicious offset of first IFD value"); return 0; } unsigned char * LastExifRefd = CharBuf; /* First directory starts 16 unsigned chars in. Offsets start at 8 unsigned chars in. */ if (!ProcessExifDir(CharBuf+14, CharBuf+6, length-6, m_exifinfo, &LastExifRefd)) return 0; /* This is how far the interesting (non thumbnail) part of the exif went. */ // int ExifSettingsLength = LastExifRefd - CharBuf; /* Compute the CCD width, in milimeters. */ if (m_exifinfo->FocalplaneXRes != 0){ m_exifinfo->CCDWidth = (float)(ExifImageWidth * m_exifinfo->FocalplaneUnits / m_exifinfo->FocalplaneXRes); } return 1; } //-------------------------------------------------------------------------- // Get 16 bits motorola order (always) for jpeg header stuff. //-------------------------------------------------------------------------- int Cexif::Get16m(void * Short) { return (((unsigned char *)Short)[0] << 8) | ((unsigned char *)Short)[1]; } //////////////////////////////////////////////////////////////////////////////// /*-------------------------------------------------------------------------- Convert a 16 bit unsigned value from file\'s native unsigned char order --------------------------------------------------------------------------*/ int Cexif::Get16u(void * Short) { if (MotorolaOrder){ return (((unsigned char *)Short)[0] << 8) | ((unsigned char *)Short)[1]; }else{ return (((unsigned char *)Short)[1] << 8) | ((unsigned char *)Short)[0]; } } //////////////////////////////////////////////////////////////////////////////// /*-------------------------------------------------------------------------- Convert a 32 bit signed value from file\'s native unsigned char order --------------------------------------------------------------------------*/ long Cexif::Get32s(void * Long) { if (MotorolaOrder){ return ((( char *)Long)[0] << 24) | (((unsigned char *)Long)[1] << 16) | (((unsigned char *)Long)[2] << 8 ) | (((unsigned char *)Long)[3] << 0 ); }else{ return ((( char *)Long)[3] << 24) | (((unsigned char *)Long)[2] << 16) | (((unsigned char *)Long)[1] << 8 ) | (((unsigned char *)Long)[0] << 0 ); } } //////////////////////////////////////////////////////////////////////////////// /*-------------------------------------------------------------------------- Convert a 32 bit unsigned value from file\'s native unsigned char order --------------------------------------------------------------------------*/ unsigned long Cexif::Get32u(void * Long) { return (unsigned long)Get32s(Long) & 0xffffffff; } //////////////////////////////////////////////////////////////////////////////// /* Describes format descriptor */ static const int BytesPerFormat[] = {0,1,1,2,4,8,1,1,2,4,8,4,8}; #define NUM_FORMATS 12 #define FMT_BYTE 1 #define FMT_STRING 2 #define FMT_USHORT 3 #define FMT_ULONG 4 #define FMT_URATIONAL 5 #define FMT_SBYTE 6 #define FMT_UNDEFINED 7 #define FMT_SSHORT 8 #define FMT_SLONG 9 #define FMT_SRATIONAL 10 #define FMT_SINGLE 11 #define FMT_DOUBLE 12 /* Describes tag values */ #define TAG_EXIF_VERSION 0x9000 #define TAG_EXIF_OFFSET 0x8769 #define TAG_INTEROP_OFFSET 0xa005 //2016年11月25日15:55:46 修改TAG_MAKE #define TAG_MAKE 0x010F #define TAG_CP 0x8298 #define TAG_MODEL 0x0110 #define TAG_ORIENTATION 0x0112 #define TAG_XRESOLUTION 0x011A #define TAG_YRESOLUTION 0x011B #define TAG_RESOLUTIONUNIT 0x0128 #define TAG_EXPOSURETIME 0x829A #define TAG_FNUMBER 0x829D #define TAG_SHUTTERSPEED 0x9201 #define TAG_APERTURE 0x9202 #define TAG_BRIGHTNESS 0x9203 #define TAG_MAXAPERTURE 0x9205 #define TAG_FOCALLENGTH 0x920A #define TAG_DATETIME_ORIGINAL 0x9003 #define TAG_USERCOMMENT 0x9286 #define TAG_SUBJECT_DISTANCE 0x9206 #define TAG_FLASH 0x9209 #define TAG_FOCALPLANEXRES 0xa20E #define TAG_FOCALPLANEYRES 0xa20F #define TAG_FOCALPLANEUNITS 0xa210 #define TAG_EXIF_IMAGEWIDTH 0xA002 #define TAG_EXIF_IMAGELENGTH 0xA003 /* the following is added 05-jan-2001 vcs */ #define TAG_EXPOSURE_BIAS 0x9204 #define TAG_WHITEBALANCE 0x9208 #define TAG_METERING_MODE 0x9207 #define TAG_EXPOSURE_PROGRAM 0x8822 #define TAG_ISO_EQUIVALENT 0x8827 #define TAG_COMPRESSION_LEVEL 0x9102 #define TAG_THUMBNAIL_OFFSET 0x0201 #define TAG_THUMBNAIL_LENGTH 0x0202 /*-------------------------------------------------------------------------- Process one of the nested EXIF directories. --------------------------------------------------------------------------*/ bool Cexif::ProcessExifDir(unsigned char * DirStart, unsigned char * OffsetBase, unsigned ExifLength, EXIFINFO * const m_exifinfo, unsigned char ** const LastExifRefdP ) { int de; int a; int NumDirEntries; unsigned ThumbnailOffset = 0; unsigned ThumbnailSize = 0; NumDirEntries = Get16u(DirStart); if ((DirStart+2+NumDirEntries*12) > (OffsetBase+ExifLength)){ strcpy(m_szLastError,"Illegally sized directory"); return 0; } for (de=0;de<NumDirEntries;de++){ int Tag, Format, Components; unsigned char * ValuePtr; /* This actually can point to a variety of things; it must be cast to other types when used. But we use it as a unsigned char-by-unsigned char cursor, so we declare it as a pointer to a generic unsigned char here. */ int BytesCount; unsigned char * DirEntry; DirEntry = DirStart+2+12*de; Tag = Get16u(DirEntry); Format = Get16u(DirEntry+2); Components = Get32u(DirEntry+4); if ((Format-1) >= NUM_FORMATS) { /* (-1) catches illegal zero case as unsigned underflows to positive large */ strcpy(m_szLastError,"Illegal format code in EXIF dir"); return 0; } BytesCount = Components * BytesPerFormat[Format]; if (BytesCount > 4){ unsigned OffsetVal; OffsetVal = Get32u(DirEntry+8); /* If its bigger than 4 unsigned chars, the dir entry contains an offset.*/ if (OffsetVal+BytesCount > ExifLength){ /* Bogus pointer offset and / or unsigned charcount value */ strcpy(m_szLastError,"Illegal pointer offset value in EXIF."); return 0; } ValuePtr = OffsetBase+OffsetVal; }else{ /* 4 unsigned chars or less and value is in the dir entry itself */ ValuePtr = DirEntry+8; } if (*LastExifRefdP < ValuePtr+BytesCount){ /* Keep track of last unsigned char in the exif header that was actually referenced. That way, we know where the discardable thumbnail data begins. */ *LastExifRefdP = ValuePtr+BytesCount; } /* Extract useful components of tag */ switch(Tag){ case TAG_MAKE: strncpy(m_exifinfo->CameraMake, (char*)ValuePtr, 31); break; case TAG_CP: strncpy(m_exifinfo->CopyRight, (char*)ValuePtr,MAX_COMMENT-1); break; case TAG_MODEL: strncpy(m_exifinfo->CameraModel, (char*)ValuePtr, 39); break; case TAG_EXIF_VERSION: strncpy(m_exifinfo->Version,(char*)ValuePtr, 4); break; case TAG_DATETIME_ORIGINAL: strncpy(m_exifinfo->DateTime, (char*)ValuePtr, 19); break; case TAG_USERCOMMENT: // Olympus has this padded with trailing spaces. Remove these first. for (a=BytesCount;;){ a--; if (((char*)ValuePtr)[a] == \' \'){ ((char*)ValuePtr)[a] = \'\\0\'; }else{ break; } if (a == 0) break; } /* Copy the comment */ if (memcmp(ValuePtr, "ASCII",5) == 0){ for (a=5;a<10;a++){ char c; c = ((char*)ValuePtr)[a]; if (c != \'\\0\' && c != \' \'){ strncpy(m_exifinfo->Comments, (char*)ValuePtr+a, 199); break; } } }else{ strncpy(m_exifinfo->Comments, (char*)ValuePtr, 199); } break; case TAG_FNUMBER: /* Simplest way of expressing aperture, so I trust it the most. (overwrite previously computd value if there is one) */ m_exifinfo->ApertureFNumber = (float)ConvertAnyFormat(ValuePtr, Format); break; case TAG_APERTURE: case TAG_MAXAPERTURE: /* More relevant info always comes earlier, so only use this field if we don\'t have appropriate aperture information yet. */ if (m_exifinfo->ApertureFNumber == 0){ m_exifinfo->ApertureFNumber = (float)exp(ConvertAnyFormat(ValuePtr, Format)*log(2.0)*0.5); } break; case TAG_BRIGHTNESS: m_exifinfo->Brightness = (float)ConvertAnyFormat(ValuePtr, Format); break; case TAG_FOCALLENGTH: /* Nice digital cameras actually save the focal length as a function of how farthey are zoomed in. */ m_exifinfo->FocalLength = (float)ConvertAnyFormat(ValuePtr, Format); break; case TAG_SUBJECT_DISTANCE: /* Inidcates the distacne the autofocus camera is focused to. Tends to be less accurate as distance increases. */ m_exifinfo->Distance = (float)ConvertAnyFormat(ValuePtr, Format); break; case TAG_EXPOSURETIME: /* Simplest way of expressing exposure time, so I trust it most. (overwrite previously computd value if there is one) */ m_exifinfo->ExposureTime = (float)ConvertAnyFormat(ValuePtr, Format); break; case TAG_SHUTTERSPEED: /* More complicated way of expressing exposure time, so only use this value if we don\'t already have it from somewhere else. */ if (m_exifinfo->ExposureTime == 0){ m_exifinfo->ExposureTime = (float) (1/exp(ConvertAnyFormat(ValuePtr, Format)*log(2.0))); } break; case TAG_FLASH: if ((int)ConvertAnyFormat(ValuePtr, Format) & 7){ m_exifinfo->FlashUsed = 1; }else{ m_exifinfo以上是关于为现有图像处理程序添加读写exif的功能的主要内容，如果未能解决你的问题，请参考以下文章