docs-desktop/dotnet-desktop-guide/framework/winforms/advanced/how-to-read-image-metadata.md

title, desription, ms.date, dev_langs, helpviewer_keywords, ms.assetid

title	desription	ms.date	dev_langs	helpviewer_keywords	ms.assetid
How to: Read Image Metadata	Learn how to read the Windows Forms PropertyItems property of an Image object to retrieve all the metadata from a file.	03/30/2017	csharp vb	metadata [Windows Forms], property item metadata [Windows Forms], reading image	72ec0b31-0be7-444a-9575-1dbcb864e0be

How to: Read Image Metadata

Some image files contain metadata that you can read to determine features of the image. For example, a digital photograph might contain metadata that you can read to determine the make and model of the camera used to capture the image. With GDI+, you can read existing metadata, and you can also write new metadata to image files.

GDI+ stores an individual piece of metadata in a xref:System.Drawing.Imaging.PropertyItem object. You can read the xref:System.Drawing.Image.PropertyItems%2A property of an xref:System.Drawing.Image object to retrieve all the metadata from a file. The xref:System.Drawing.Image.PropertyItems%2A property returns an array of xref:System.Drawing.Imaging.PropertyItem objects.

A xref:System.Drawing.Imaging.PropertyItem object has the following four properties: Id, Value, Len, and Type.

Id

A tag that identifies the metadata item. Some values that can be assigned to xref:System.Drawing.Imaging.PropertyItem.Id%2A are shown in the following table:

Hexadecimal value	Description
0x0320 0x010F 0x0110 0x9003 0x829A 0x5090 0x5091	Image title Equipment manufacturer Equipment model ExifDTOriginal Exif exposure time Luminance table Chrominance table

Value

An array of values. The format of the values is determined by the xref:System.Drawing.Imaging.PropertyItem.Type%2A property.

Len

The length (in bytes) of the array of values pointed to by the xref:System.Drawing.Imaging.PropertyItem.Value%2A property.

Type

The data type of the values in the array pointed to by the Value property. The formats indicated by the Type property values are shown in the following table:

Numeric value	Description
1	A Byte
2	An array of Byte objects encoded as ASCII
3	A 16-bit integer
4	A 32-bit integer
5	An array of two Byte objects that represent a rational number
6	Not used
7	Undefined
8	Not used
9	SLong
10	SRational

Example

The following code example reads and displays the seven pieces of metadata in the file FakePhoto.jpg. The second (index 1) property item in the list has xref:System.Drawing.Imaging.PropertyItem.Id%2A 0x010F (equipment manufacturer) and xref:System.Drawing.Imaging.PropertyItem.Type%2A 2 (ASCII-encoded byte array). The code example displays the value of that property item.

[!code-csharpSystem.Drawing.WorkingWithImages#51] [!code-vbSystem.Drawing.WorkingWithImages#51]

The code produces output similar to the following:

 Property Item 0
  
 id: 0x320
  
 type: 2

 length: 16 bytes
  
 Property Item 1
  
 id: 0x10f
  
 type: 2
  
 length: 17 bytes
  
 Property Item 2
  
 id: 0x110
  
 type: 2
  
 length: 7 bytes
  
 Property Item 3
  
 id: 0x9003
  
 type: 2
  
 length: 20 bytes
  
 Property Item 4
  
 id: 0x829a
  
 type: 5
  
 length: 8 bytes
  
 Property Item 5
  
 id: 0x5090
  
 type: 3
  
 length: 128 bytes
  
 Property Item 6
  
 id: 0x5091
  
 type: 3
  
 length: 128 bytes
  
 The equipment make is Northwind Camera.

Compiling the Code

The preceding example is designed for use with Windows Forms, and it requires xref:System.Windows.Forms.PaintEventArgs e, which is a parameter of the xref:System.Windows.Forms.Control.Paint event handler. Handle the form's xref:System.Windows.Forms.Control.Paint event and paste this code into the paint event handler. You must replace FakePhoto.jpg with an image name and path valid on your system and import the System.Drawing.Imaging namespace.

See also

• Images, Bitmaps, and Metafiles
• Working with Images, Bitmaps, Icons, and Metafiles