ImageLevels

ImageLevels[image]
gives a list of pixel values and counts for each channel in image.

ImageLevels[image,bspec]
bins pixel values using bin specification bspec.

ImageLevels[image,bspec,range]
gives counts for bins in the given range.

Details and OptionsDetails and Options

  • ImageLevels returns a list of levels for each channel in the form {{lev1,k1},{lev2,k2},}, where ki counts the values satisfying , except for the last bin, which uses .
  • Binary images have the form {{0,n0},{1,n1}}.
  • ImageLevels works with arbitrary grayscale and multichannel 2D and 3D images.
  • The binning specification bspec, which by default uses 256 levels, can be any of the following:
  • nn equally spaced bins
    Automaticautomatic choice of binning
    Allreturn tally of all available pixel values
    "Byte"256 levels after converting data values to a "Byte" type
  • The range can be of the following forms:
  • Automaticautomatic ranges depending on the color space
    Allinclude all values for each channel
    {All,max}include values below max
    {min,All}include values above min
    {min,max}include values between min and max
    {range1,}different ranges for each channel
  • The following defaults are used for range, depending on the image color space. The ranges are chosen to include the subspace of the "RGB" color space.
  • "Grayscale","RGB","CMYK","HSB"{0,1}
    "XYZ"{{0,0.97},{0,1},{0,0.83}}
    "LAB"{{0,1},{-0.8,0.94},{-1.13,0.94}}
    "LCH"{{0,1},{0,1.3},{0,1}}
    "LUV"{{0,1},{-0.85,1.76},{-1.26,0.88}}
  • The following options can be specified:
  • Method"IncludeOutOfRange"method to use
  • Possible settings for Method include:
  • "IncludeOutOfRange"values below range in first bin and values above range in last bin
    "ExcludeOutOfRange"do not count out-of-range values

ExamplesExamplesopen allclose all

Basic Examples  (3)Basic Examples  (3)

Count the number of pixels in each of 10 intensity levels:

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Levels of an RGB image:

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Intensity levels of a 3D image:

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Introduced in 2010
(8.0)
| Updated in 2014
(10.0)
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