[ASP.NET][C#] EXIF 태그 읽기

*PropertyItem

Id의 속성 https://msdn.microsoft.com/en-us/library/system.drawing.imaging.propertyitem.id(v=vs.110).aspx

Type의 속성 https://msdn.microsoft.com/ko-kr/library/system.drawing.imaging.propertyitem.type(v=vs.110).aspx

메타데이터 reference http://www.exiv2.org/tags.html

C#에서 바로 다루는 방법 http://motolies.com/186

*ExifLibrary

ExifLib https://www.codeproject.com/Articles/36342/ExifLib-A-Fast-Exif-Data-Extractor-for-NET-2-0 

ExifLibrary https://blog.naver.com/ivory82/40200445146

ExifLibrary for .NET https://www.codeproject.com/Articles/43665/ExifLibrary-for-NET 

ExifLibrary  https://code.google.com/archive/p/exiflibrary/issues/46

*DLL 추가

http://marufloor.tistory.com/79 -> 적용해보았으나 작동X

3/12

*JS에서 Exif Library 다루기

http://danielhindrikes.se/web/get-coordinates-from-photo-with-javascript/

#

   /* getExifGPSTagValueByImgProperties : 사진의 Exif GPS Tag 읽어오기 */

        public Dictionary<string, object> getExifGPSTagValueByImgProperties(string filePath)

        {

            String exifFilePath = @filePath;

            Dictionary<string, object> result = null;

            Image image = null;

            try

            {

                FileStream fs = new FileStream(exifFilePath, FileMode.Open, FileAccess.Read);

                image = Image.FromStream(fs);

                result = new Dictionary<string, object>();

                if (Array.IndexOf<int>(image.PropertyIdList, 1) != -1 &&

                            Array.IndexOf<int>(image.PropertyIdList, 2) != -1 &&

                            Array.IndexOf<int>(image.PropertyIdList, 3) != -1 &&

                            Array.IndexOf<int>(image.PropertyIdList, 4) != -1)

                {

                    string gpsLatitudeRef = BitConverter.ToChar(image.GetPropertyItem(1).Value, 0).ToString();

                    string latitude = DecodeRational64u(image.GetPropertyItem(2));

                    string gpsLongitudeRef = BitConverter.ToChar(image.GetPropertyItem(3).Value, 0).ToString();

                    string longitude = DecodeRational64u(image.GetPropertyItem(4));

                    result.Add("txtDroneImageLon", longitude);

                    result.Add("txtDroneImageLat", latitude);

                    Console.WriteLine("{0}\t{1} {2}, {3} {4}", exifFilePath, gpsLatitudeRef, latitude, gpsLongitudeRef, longitude);

                }

                image.Dispose();

                fs.Close();

            }

            catch (Exception)

            {

                return result;

            }

            return result;

        } // end getLonLat()

        private static string DecodeRational64u(System.Drawing.Imaging.PropertyItem propertyItem)

        {

            uint dN = BitConverter.ToUInt32(propertyItem.Value, 0);

            uint dD = BitConverter.ToUInt32(propertyItem.Value, 4);

            uint mN = BitConverter.ToUInt32(propertyItem.Value, 8);

            uint mD = BitConverter.ToUInt32(propertyItem.Value, 12);

            uint sN = BitConverter.ToUInt32(propertyItem.Value, 16);

            uint sD = BitConverter.ToUInt32(propertyItem.Value, 20);

            decimal deg;

            decimal min;

            decimal sec;

            // Found some examples where you could get a zero denominator and no one likes to devide by zero

            if (dD > 0) { deg = (decimal)dN / dD; } else { deg = dN; }

            if (mD > 0) { min = (decimal)mN / mD; } else { min = mN; }

            if (sD > 0) { sec = (decimal)sN / sD; } else { sec = sN; }

            //if (sec == 0) return string.Format("{0}° {1:0.###}'", deg, min);

            //else return string.Format("{0}° {1:0}' {2:0.#}\"", deg, min, sec);

            decimal result;

            if (sec == 0) result = deg + (min / 60);

            else result = deg + (min / 60) + (sec / 3600);

            return Math.Round(result, 8).ToString();

        }