File Formats: Exif Formats (TIFF and JPG)

Exif is a standard for image files created with digital cameras and other input devices. The standard set by the Japan Electronic Industry Development Association, and formally it is called the Digital Still Camera Image File Format Standard.

Exif files contain either uncompressed TIFF images or compressed JPEG images. In addition, these files can contain many comment fields of various types. You can use ReadComment to read comments in an existing file. Before writing a file, you can use the Comments property to set an array of comments to be saved in the file. For more information about comments, refer to RasterCommentMetadataType Enumeration.

LEADTOOLS reads and writes the following Exif formats:

TIFF. This is a tag-based file format designed to promote universal interchanges of digital image data. You can save any image size.

You can read and write 24 bits per pixel.

Whenever you save an image containing a region as a TIFF file format, the region is also saved. Note, however, that the ability to save a region inside a TIFF file must be unlocked. This requires a Document Imaging or Medical Imaging toolkit.

JPG. This is the JPEG format with YUV 4:2:2 sampling. You can save any image size.

You can read and write 24 bits per pixel. (Grayscale is not supported.) For more information, refer to Compression Using LEAD and JPEG Formats.

An Exif JPG file can also contain a stamp (thumbnail) image, which is a small copy of the main image. The stamp size has been restricted to 160x120x24. When saving Exif files, the StampWidth, StampHeight, and StampBitsPerPixelproperties will be ignored and 160 (StampWidth), 120 (StampHeight) and 24 (StampBitsPerPixel) will be used instead. That limitation has been imposed in order to conform with the ExifR98 interoperability rules imposed by Japanese digital camera manufacturers.

If you are working with uncompressed (TIFF) Exif files, the stamp size is (width x height x 24 bpp), with no limitations on width and height.

Note: LEADTOOLS will currently write version 2.21 of these files. But it can read earlier or later versions as the file format is designed to be backward compatible."

To load a stamp image from a file, use the ReadStamp method.

Constant	Read Support	Write Support	Description
Exif	24 BPP	24 BPP	Exif file containing a TIFF image, with no compression and with RGB color space.
ExifYcc	24 BPP	24 BPP	Exif file containing a TIFF image, with no compression and with YCbCr color space.
ExifJpeg422	24 BPP	24 BPP	Exif file containing a JPEG compressed image and YUV 4:2:2 color space.
ExifJpeg411	24 BPP	24 BPP	Exif file containing a JPEG compressed image and YUV 4:1:1 color space.

Required DLL: Leadtools.Codecs.Tif.Dll and Leadtools.Codecs.Cmp.Dll. For a listing of the exact DLLs needed, based on the toolkit version, refer to Files To Be Included With Your Application To Be Included .

Platforms: .NET 2/3, .NET 4, Silverlight