Discovering the Property Items present in an image.

Image file formats will always provide pertinent data about the size and resolution of an image. These are fundamental to reading and decoding the picture. In some cases, such as the pixel bit depth of GIF files, certain properties are implied. In other cases, explicit metadata detailing the pixel format, the time that the image was created and other useful information is encapsulated in the file.

GDI+ enables you to read this metadata from the image in the form of a collection of PropertyItem objects. There are many possible PropertyItem identifiers which are coded internally as a standard identification number, the length of the data, a value type and a value to associate with the identification.

The Image class contains the PropertyItems collection which can be iterated quite simply to obtain each of the property items in turn. To extract the useful information, the meaning of the tag, the type of value contained and the actual values can be displayed or analysed by your code. The program in listing 1 performs the function of reading all the tags in an image, ascertaining which image property tags are present and decoding them line by line in a text list.

A detailed listing of the property item tags may be found in the MSDN help that comes with Visual Studio or online here

Listing 1:

using System;

using System.Text;

using System.Drawing;

using System.Drawing.Imaging;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

namespace ImageAnalyser

{

/// <summary>

/// Summary description for Form1.

/// </summary>

public class Form1 : System.Windows.Forms.Form

{

private System.Windows.Forms.TextBox textBox1;

private System.Windows.Forms.Button button1;

private System.Windows.Forms.Button button2;

/// <summary>

/// Required designer variable.

/// </summary>

private System.ComponentModel.Container components = null;

public Form1()

{

// Required for Windows Form Designer support

InitializeComponent();

// TODO: Add any constructor code after InitializeComponent call

}

/// <summary>

/// Clean up any resources being used.

/// </summary>

protected override void Dispose( bool disposing )

{

if( disposing )

{

if (components != null)

{

components.Dispose();

}

base.Dispose( disposing );

}

#region Windows Form Designer generated code

/// <summary>

/// Required method for Designer support - do not modify

/// the contents of this method with the code editor.

/// </summary>

private void InitializeComponent()

{

this.textBox1 = new System.Windows.Forms.TextBox();

this.button1 = new System.Windows.Forms.Button();

this.button2 = new System.Windows.Forms.Button();

this.SuspendLayout();

// textBox1

this.textBox1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)

| System.Windows.Forms.AnchorStyles.Left)

| System.Windows.Forms.AnchorStyles.Right)));

this.textBox1.Font = new System.Drawing.Font("Courier New", 8.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((System.Byte)(0)));

this.textBox1.Location = new System.Drawing.Point(8, 16);

this.textBox1.Multiline = true;

this.textBox1.Name = "textBox1";

this.textBox1.ScrollBars = System.Windows.Forms.ScrollBars.Both;

this.textBox1.Size = new System.Drawing.Size(332, 311);

this.textBox1.TabIndex = 0;

this.textBox1.Text = "";

// button1

this.button1.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));

this.button1.Location = new System.Drawing.Point(360, 32);

this.button1.Name = "button1";

this.button1.Size = new System.Drawing.Size(64, 24);

this.button1.TabIndex = 1;

this.button1.Text = "Load";

this.button1.Click += new System.EventHandler(this.button1_Click);

// button2

this.button2.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));

this.button2.Location = new System.Drawing.Point(352, 224);

this.button2.Name = "button2";

this.button2.TabIndex = 2;

this.button2.Text = "Quit";

this.button2.Click += new System.EventHandler(this.button2_Click);

// Form1

this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);

this.ClientSize = new System.Drawing.Size(440, 344);

this.Controls.Add(this.button2);

this.Controls.Add(this.button1);

this.Controls.Add(this.textBox1);

this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.SizableToolWindow;

this.Name = "Form1";

this.Text = "Form1";

this.ResumeLayout(false);

}

#endregion

/// <summary>

/// The main entry point for the application.

/// </summary>

[STAThread]

static void Main()

{

Application.Run(new Form1());

}

private void button2_Click(object sender, System.EventArgs e)

{

Application.Exit();

}

string DumpValues(byte[] v)

{

StringBuilder sb=new StringBuilder();

int index1=0;

int index2=0;

for(index1=0; index1<v.Length; index1+=16)

{

sb.Append("\t");

for(index2=0; index2<16; index2++)

{

if(index1+index2<v.Length)

sb.Append(v[index1+index2].ToString("X02")+" ");

else

sb.Append(" ");

}

sb.Append("\t");

for(index2=0; index2<16; index2++)

{

if(index1+index2<v.Length)

{

char c=(char)v[index1+index2];

if(c<0x20)

sb.Append(".");

else

sb.Append(c);

}

sb.Append("\r\n");

}

return sb.ToString();

}

private void button1_Click(object sender, System.EventArgs e)

{

OpenFileDialog dlg=new OpenFileDialog();

dlg.Filter="Image files|*.tif;*.jpg;*.jpeg;*.bmp;*.tiff;*.gif";

if(dlg.ShowDialog()==DialogResult.OK)

{

Image img = Image.FromFile(dlg.FileName);

this.textBox1.Text="";

StringBuilder sb=new StringBuilder();

sb.Append(string.Format(

"Image: {0}\r\n"+

"Width= {1}, Height= {2}\r\n"+

"PixelFormat = {3}\r\n"+

"Dumping {4} property items:",dlg.FileName,img.Width,img.Height,img.PixelFormat,img.PropertyItems.Length));

foreach(PropertyItem i in img.PropertyItems)

{

string s="UnknownTag";

switch(i.Id)

{

case 0x0000 :

s="PropertyTagGpsVer ";

break;

case 0x0001 :

s="PropertyTagGpsLatitudeRef ";

break;

case 0x0002 :

s="PropertyTagGpsLatitude ";

break;

case 0x0003 :

s="PropertyTagGpsLongitudeRef ";

break;

case 0x0004 :

s="PropertyTagGpsLongitude ";

break;

case 0x0005 :

s="PropertyTagGpsAltitudeRef ";

break;

case 0x0006 :

s="PropertyTagGpsAltitude ";

break;

case 0x0007 :

s="PropertyTagGpsGpsTime ";

break;

case 0x0008 :

s="PropertyTagGpsGpsSatellites ";

break;

case 0x0009 :

s="PropertyTagGpsGpsStatus ";

break;

case 0x000A :

s="PropertyTagGpsGpsMeasureMode ";

break;

case 0x000B :

s="PropertyTagGpsGpsDop ";

break;

case 0x000C :

s="PropertyTagGpsSpeedRef ";

break;

case 0x000D :

s="PropertyTagGpsSpeed ";

break;

case 0x000E :

s="PropertyTagGpsTrackRef ";

break;

case 0x000F :

s="PropertyTagGpsTrack ";

break;

case 0x0010 :

s="PropertyTagGpsImgDirRef ";

break;

case 0x0011 :

s="PropertyTagGpsImgDir ";

break;

case 0x0012 :

s="PropertyTagGpsMapDatum ";

break;

case 0x0013 :

s="PropertyTagGpsDestLatRef ";

break;

case 0x0014 :

s="PropertyTagGpsDestLat ";

break;

case 0x0015 :

s="PropertyTagGpsDestLongRef ";

break;

case 0x0016 :

s="PropertyTagGpsDestLong ";

break;

case 0x0017 :

s="PropertyTagGpsDestBearRef ";

break;

case 0x0018 :

s="PropertyTagGpsDestBear ";

break;

case 0x0019 :

s="PropertyTagGpsDestDistRef ";

break;

case 0x001A :

s="PropertyTagGpsDestDist ";

break;

case 0x00FE :

s="PropertyTagNewSubfileType ";

break;

case 0x00FF :

s="PropertyTagSubfileType ";

break;

case 0x0100 :

s="PropertyTagImageWidth ";

break;

case 0x0101 :

s="PropertyTagImageHeight ";

break;

case 0x0102 :

s="PropertyTagBitsPerSample ";

break;

case 0x0103 :

s="PropertyTagCompression ";

break;

case 0x0106 :

s="PropertyTagPhotometricInterp ";

break;

case 0x0107 :

s="PropertyTagThreshHolding ";

break;

case 0x0108 :

s="PropertyTagCellWidth ";

break;

case 0x0109 :

s="PropertyTagCellHeight ";

break;

case 0x010A :

s="PropertyTagFillOrder ";

break;

case 0x010D :

s="PropertyTagDocumentName ";

break;

case 0x010E :

s="PropertyTagImageDescription ";

break;

case 0x010F :

s="PropertyTagEquipMake ";

break;

case 0x0110 :

s="PropertyTagEquipModel ";

break;

case 0x0111 :

s="PropertyTagStripOffsets ";

break;

case 0x0112 :

s="PropertyTagOrientation ";

break;

case 0x0115 :

s="PropertyTagSamplesPerPixel ";

break;

case 0x0116 :

s="PropertyTagRowsPerStrip ";

break;

case 0x0117 :

s="PropertyTagStripBytesCount ";

break;

case 0x0118 :

s="PropertyTagMinSampleValue ";

break;

case 0x0119 :

s="PropertyTagMaxSampleValue ";

break;

case 0x011A :

s="PropertyTagXResolution ";

break;

case 0x011B :

s="PropertyTagYResolution ";

break;

case 0x011C :

s="PropertyTagPlanarConfig ";

break;

case 0x011D :

s="PropertyTagPageName ";

break;

case 0x011E :

s="PropertyTagXPosition ";

break;

case 0x011F :

s="PropertyTagYPosition ";

break;

case 0x0120 :

s="PropertyTagFreeOffset ";

break;

case 0x0121 :

s="PropertyTagFreeByteCounts ";

break;

case 0x0122 :

s="PropertyTagGrayResponseUnit ";

break;

case 0x0123 :

s="PropertyTagGrayResponseCurve ";

break;

case 0x0124 :

s="PropertyTagT4Option ";

break;

case 0x0125 :

s="PropertyTagT6Option ";

break;

case 0x0128 :

s="PropertyTagResolutionUnit ";

break;

case 0x0129 :

s="PropertyTagPageNumber ";

break;

case 0x012D :

s="PropertyTagTransferFunction ";

break;

case 0x0131 :

s="PropertyTagSoftwareUsed ";

break;

case 0x0132 :

s="PropertyTagDateTime ";

break;

case 0x013B :

s="PropertyTagArtist ";

break;

case 0x013C :

s="PropertyTagHostComputer ";

break;

case 0x013D :

s="PropertyTagPredictor ";

break;

case 0x013E :

s="PropertyTagWhitePoint ";

break;

case 0x013F :

s="PropertyTagPrimaryChromaticities ";

break;

case 0x0140 :

s="PropertyTagColorMap ";

break;

case 0x0141 :

s="PropertyTagHalftoneHints ";

break;

case 0x0142 :

s="PropertyTagTileWidth ";

break;

case 0x0143 :

s="PropertyTagTileLength ";

break;

case 0x0144 :

s="PropertyTagTileOffset ";

break;

case 0x0145 :

s="PropertyTagTileByteCounts ";

break;

case 0x014C :

s="PropertyTagInkSet ";

break;

case 0x014D :

s="PropertyTagInkNames ";

break;

case 0x014E :

s="PropertyTagNumberOfInks ";

break;

case 0x0150 :

s="PropertyTagDotRange ";

break;

case 0x0151 :

s="PropertyTagTargetPrinter ";

break;

case 0x0152 :

s="PropertyTagExtraSamples ";

break;

case 0x0153 :

s="PropertyTagSampleFormat ";

break;

case 0x0154 :

s="PropertyTagSMinSampleValue ";

break;

case 0x0155 :

s="PropertyTagSMaxSampleValue ";

break;

case 0x0156 :

s="PropertyTagTransferRange ";

break;

case 0x0200 :

s="PropertyTagJPEGProc ";

break;

case 0x0201 :

s="PropertyTagJPEGInterFormat ";

break;

case 0x0202 :

s="PropertyTagJPEGInterLength ";

break;

case 0x0203 :

s="PropertyTagJPEGRestartInterval ";

break;

case 0x0205 :

s="PropertyTagJPEGLosslessPredictors ";

break;

case 0x0206 :

s="PropertyTagJPEGPointTransforms ";

break;

case 0x0207 :

s="PropertyTagJPEGQTables ";

break;

case 0x0208 :

s="PropertyTagJPEGDCTables ";

break;

case 0x0209 :

s="PropertyTagJPEGACTables ";

break;

case 0x0211 :

s="PropertyTagYCbCrCoefficients ";

break;

case 0x0212 :

s="PropertyTagYCbCrSubsampling ";

break;

case 0x0213 :

s="PropertyTagYCbCrPositioning ";

break;

case 0x0214 :

s="PropertyTagREFBlackWhite ";

break;

case 0x0301 :

s="PropertyTagGamma ";

break;

case 0x0302 :

s="PropertyTagICCProfileDescriptor ";

break;

case 0x0303 :

s="PropertyTagSRGBRenderingIntent ";

break;

case 0x0320 :

s="PropertyTagImageTitle ";

break;

case 0x5001 :

s="PropertyTagResolutionXUnit ";

break;

case 0x5002 :

s="PropertyTagResolutionYUnit ";

break;

case 0x5003 :

s="PropertyTagResolutionXLengthUnit ";

break;

case 0x5004 :

s="PropertyTagResolutionYLengthUnit ";

break;

case 0x5005 :

s="PropertyTagPrintFlags ";

break;

case 0x5006 :

s="PropertyTagPrintFlagsVersion ";

break;

case 0x5007 :

s="PropertyTagPrintFlagsCrop ";

break;

case 0x5008 :

s="PropertyTagPrintFlagsBleedWidth ";

break;

case 0x5009 :

s="PropertyTagPrintFlagsBleedWidthScale ";

break;

case 0x500A :

s="PropertyTagHalftoneLPI ";

break;

case 0x500B :

s="PropertyTagHalftoneLPIUnit ";

break;

case 0x500C :

s="PropertyTagHalftoneDegree ";

break;

case 0x500D :

s="PropertyTagHalftoneShape ";

break;

case 0x500E :

s="PropertyTagHalftoneMisc ";

break;

case 0x500F :

s="PropertyTagHalftoneScreen ";

break;

case 0x5010 :

s="PropertyTagJPEGQuality ";

break;

case 0x5011 :

s="PropertyTagGridSize ";

break;

case 0x5012 :

s="PropertyTagThumbnailFormat ";

break;

case 0x5013 :

s="PropertyTagThumbnailWidth ";

break;

case 0x5014 :

s="PropertyTagThumbnailHeight ";

break;

case 0x5015 :

s="PropertyTagThumbnailColorDepth ";

break;

case 0x5016 :

s="PropertyTagThumbnailPlanes ";

break;

case 0x5017 :

s="PropertyTagThumbnailRawBytes ";

break;

case 0x5018 :

s="PropertyTagThumbnailSize ";

break;

case 0x5019 :

s="PropertyTagThumbnailCompressedSize ";

break;

case 0x501A :

s="PropertyTagColorTransferFunction ";

break;

case 0x501B :

s="PropertyTagThumbnailData ";

break;

case 0x5020 :

s="PropertyTagThumbnailImageWidth ";

break;

case 0x5021 :

s="PropertyTagThumbnailImageHeight ";

break;

case 0x5022 :

s="PropertyTagThumbnailBitsPerSample ";

break;

case 0x5023 :

s="PropertyTagThumbnailCompression ";

break;

case 0x5024 :

s="PropertyTagThumbnailPhotometricInterp ";

break;

case 0x5025 :

s="PropertyTagThumbnailImageDescription ";

break;

case 0x5026 :

s="PropertyTagThumbnailEquipMake ";

break;

case 0x5027 :

s="PropertyTagThumbnailEquipModel ";

break;

case 0x5028 :

s="PropertyTagThumbnailStripOffsets ";

break;

case 0x5029 :

s="PropertyTagThumbnailOrientation ";

break;

case 0x502A :

s="PropertyTagThumbnailSamplesPerPixel ";

break;

case 0x502B :

s="PropertyTagThumbnailRowsPerStrip ";

break;

case 0x502C :

s="PropertyTagThumbnailStripBytesCount ";

break;

case 0x502D :

s="PropertyTagThumbnailResolutionX ";

break;

case 0x502E :

s="PropertyTagThumbnailResolutionY ";

break;

case 0x502F :

s="PropertyTagThumbnailPlanarConfig ";

break;

case 0x5030 :

s="PropertyTagThumbnailResolutionUnit ";

break;

case 0x5031 :

s="PropertyTagThumbnailTransferFunction ";

break;

case 0x5032 :

s="PropertyTagThumbnailSoftwareUsed ";

break;

case 0x5033 :

s="PropertyTagThumbnailDateTime ";

break;

case 0x5034 :

s="PropertyTagThumbnailArtist ";

break;

case 0x5035 :

s="PropertyTagThumbnailWhitePoint ";

break;

case 0x5036 :

s="PropertyTagThumbnailPrimaryChromaticities ";

break;

case 0x5037 :

s="PropertyTagThumbnailYCbCrCoefficients ";

break;

case 0x5038 :

s="PropertyTagThumbnailYCbCrSubsampling ";

break;

case 0x5039 :

s="PropertyTagThumbnailYCbCrPositioning ";

break;

case 0x503A :

s="PropertyTagThumbnailRefBlackWhite ";

break;

case 0x503B :

s="PropertyTagThumbnailCopyRight ";

break;

case 0x5090 :

s="PropertyTagLuminanceTable ";

break;

case 0x5091 :

s="PropertyTagChrominanceTable ";

break;

case 0x5100 :

s="PropertyTagFrameDelay ";

break;

case 0x5101 :

s="PropertyTagLoopCount ";

break;

case 0x5102 :

s="PropertyTagGlobalPalette ";

break;

case 0x5103 :

s="PropertyTagIndexBackground ";

break;

case 0x5104 :

s="PropertyTagIndexTransparent ";

break;

case 0x5110 :

s="PropertyTagPixelUnit ";

break;

case 0x5111 :

s="PropertyTagPixelPerUnitX ";

break;

case 0x5112 :

s="PropertyTagPixelPerUnitY ";

break;

case 0x5113 :

s="PropertyTagPaletteHistogram ";

break;

case 0x8298 :

s="PropertyTagCopyright ";

break;

case 0x829A :

s="PropertyTagExifExposureTime ";

break;

case 0x829D :

s="PropertyTagExifFNumber ";

break;

case 0x8769 :

s="PropertyTagExifIFD ";

break;

case 0x8773 :

s="PropertyTagICCProfile ";

break;

case 0x8822 :

s="PropertyTagExifExposureProg ";

break;

case 0x8824 :

s="PropertyTagExifSpectralSense ";

break;

case 0x8825 :

s="PropertyTagGpsIFD ";

break;

case 0x8827 :

s="PropertyTagExifISOSpeed ";

break;

case 0x8828 :

s="PropertyTagExifOECF ";

break;

case 0x9000 :

s="PropertyTagExifVer ";

break;

case 0x9003 :

s="PropertyTagExifDTOrig ";

break;

case 0x9004 :

s="PropertyTagExifDTDigitized ";

break;

case 0x9101 :

s="PropertyTagExifCompConfig ";

break;

case 0x9102 :

s="PropertyTagExifCompBPP ";

break;

case 0x9201 :

s="PropertyTagExifShutterSpeed ";

break;

case 0x9202 :

s="PropertyTagExifAperture ";

break;

case 0x9203 :

s="PropertyTagExifBrightness ";

break;

case 0x9204 :

s="PropertyTagExifExposureBias ";

break;

case 0x9205 :

s="PropertyTagExifMaxAperture ";

break;

case 0x9206 :

s="PropertyTagExifSubjectDist ";

break;

case 0x9207 :

s="PropertyTagExifMeteringMode ";

break;

case 0x9208 :

s="PropertyTagExifLightSource ";

break;

case 0x9209 :

s="PropertyTagExifFlash ";

break;

case 0x920A :

s="PropertyTagExifFocalLength ";

break;

case 0x927C :

s="PropertyTagExifMakerNote ";

break;

case 0x9286 :

s="PropertyTagExifUserComment ";

break;

case 0x9290 :

s="PropertyTagExifDTSubsec ";

break;

case 0x9291 :

s="PropertyTagExifDTOrigSS ";

break;

case 0x9292 :

s="PropertyTagExifDTDigSS ";

break;

case 0xA000 :

s="PropertyTagExifFPXVer ";

break;

case 0xA001 :

s="PropertyTagExifColorSpace ";

break;

case 0xA002 :

s="PropertyTagExifPixXDim ";

break;

case 0xA003 :

s="PropertyTagExifPixYDim ";

break;

case 0xA004 :

s="PropertyTagExifRelatedWav ";

break;

case 0xA005 :

s="PropertyTagExifInterop ";

break;

case 0xA20B :

s="PropertyTagExifFlashEnergy ";

break;

case 0xA20C :

s="PropertyTagExifSpatialFR ";

break;

case 0xA20E :

s="PropertyTagExifFocalXRes ";

break;

case 0xA20F :

s="PropertyTagExifFocalYRes ";

break;

case 0xA210 :

s="PropertyTagExifFocalResUnit ";

break;

case 0xA214 :

s="PropertyTagExifSubjectLoc ";

break;

case 0xA215 :

s="PropertyTagExifExposureIndex ";

break;

case 0xA217 :

s="PropertyTagExifSensingMethod ";

break;

case 0xA300 :

s="PropertyTagExifFileSource ";

break;

case 0xA301 :

s="PropertyTagExifSceneType ";

break;

case 0xA302 :

s="PropertyTagExifCfaPattern ";

break;

}

sb.Append(s+"\r\n");

string t="UnknownType";

switch(i.Type)

{

case 1:

t="PropertyTagTypeByte";

break;

case 2:

t="PropertyTagTypeASCII";

break;

case 3:

t="PropertyTagTypeShort";

break;

case 4:

t="PropertyTagTypeLong";

break;

case 5:

t="PropertyTagTypeRational";

break;

case 7:

t="PropertyTagTypeUndefined";

break;

case 9:

t="PropertyTagTypeSLONG";

break;

case 10:

t="PropertyTagTypeSRational";

break;

}

sb.Append(string.Format(

"\tType:{0}\r\n"+

"\tLength:{1}\r\n"+

"\tValues:\r\n{2}\r\n",

t,i.Len,DumpValues(i.Value)

));

}

this.textBox1.Text=sb.ToString();

}

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