imfinfo (MATLAB Function Reference)

Return information about a graphics file

info = imfinfo(filename,fmt)
info = imfinfo(filename)

Description

info = imfinfo(filename,fmt)

returns a structure whose fields contain information about an image in a graphics file. filename is a string that specifies the name of the graphics file, and fmt is a string that specifies the format of the file. The file must be in the current directory or in a directory on the MATLAB path. If imfinfo cannot find a file named filename, it looks for a file named
filename.fmt.

This table lists the possible values for fmt:


Format	File type
`'bmp'`	Windows Bitmap (BMP)
`'hdf'`	Hierarchical Data Format (HDF)
`'jpg' or 'jpeg'`	Joint Photographic Experts Group (JPEG)
`'pcx'`	Windows Paintbrush (PCX)
`'tif' or 'tiff'`	Tagged Image File Format (TIFF)
`'xwd'`	X Windows Dump (XWD)

If filename is a TIFF or HDF file containing more than one image, info is a structure array with one element (i.e., an individual structure) for each image in the file. For example, info(3) would contain information about the third image in the file.

The set of fields in info depends on the individual file and its format. However, the first nine fields are always the same. This table lists these fields and describes their values:


Field	Value
`Filename`	A string containing the name of the file; if the file is not in the current directory, the string contains the full pathname of the file
`FileModDate`	A string containing the date when the file was last modified
`FileSize`	An integer indicating the size of the file in bytes
`Format`	A string containing the file format, as specified by `fmt`; for JPEG and TIFF files, the three-letter variant is returned
`FormatVersion`	A string or number describing the version of the format
`Width`	An integer indicating the width of the image in pixels
`Height`	An integer indicating the height of the image in pixels
`BitDepth`	An integer indicating the number of bits per pixel
`ColorType`	A string indicating the type of image; either `'truecolor'` for a truecolor RGB image, `'grayscale'` for a grayscale intensity image, or `'indexed'` for an indexed image

info = imfinfo(filename) attempts to infer the format of the file from its content.

Example

info = imfinfo('flowers.bmp')

info = 

              Filename: 'flowers.bmp'
           FileModDate: '16-Oct-1996 11:41:38'
              FileSize: 182078
                Format: 'bmp'
         FormatVersion: 'Version 3 (Microsoft Windows 3.x)'
                 Width: 500
                Height: 362
              BitDepth: 8
             ColorType: 'indexed'
       FormatSignature: 'BM'
    NumColormapEntries: 256
              Colormap: [256x3  double]
               RedMask: []
             GreenMask: []
              BlueMask: []
       ImageDataOffset: 1078
      BitmapHeaderSize: 40
             NumPlanes: 1
       CompressionType: 'none'
            BitmapSize: 181000
        HorzResolution: 0
        VertResolution: 0
         NumColorsUsed: 256
    NumImportantColors: 0