Method: Magick::Image#channel_mean

Defined in:
ext/RMagick/rmimage.cpp

#channel_mean(channel = Magick::AllChannels) ⇒ Array<Float> #channel_mean(*channels) ⇒ Array<Float>

Returns the mean and standard deviation values for the specified channel or channels.

Overloads:

  • #channel_mean(channel = Magick::AllChannels) ⇒ Array<Float>

    Parameters:

    • channel (Magick::ChannelType) (defaults to: Magick::AllChannels) —

      a ChannelType arguments.

  • #channel_mean(*channels) ⇒ Array<Float>

    Parameters:

    • *channels (Magick::ChannelType) —

      one or more ChannelType arguments.

Returns:

  • (Array<Float>) —

    The first element in the array is the mean value. The second element is the standard deviation.



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# File 'ext/RMagick/rmimage.cpp', line 2550

VALUE
Image_channel_mean(int argc, VALUE *argv, VALUE self)
{
    Image *image;
    ChannelType channels;
    ExceptionInfo *exception;
    double mean, stddev;
    VALUE ary;

    image = rm_check_destroyed(self);

    channels = extract_channels(&argc, argv);

    // Ensure all arguments consumed.
    if (argc > 0)
    {
        raise_ChannelType_error(argv[argc-1]);
    }

    exception = AcquireExceptionInfo();
#if defined(IMAGEMAGICK_7)
    BEGIN_CHANNEL_MASK(image, channels);
    GVL_STRUCT_TYPE(GetImageMean) args = { image, &mean, &stddev, exception };
    CALL_FUNC_WITHOUT_GVL(GVL_FUNC(GetImageMean), &args);
    END_CHANNEL_MASK(image);
#else
    GVL_STRUCT_TYPE(GetImageChannelMean) args = { image, channels, &mean, &stddev, exception };
    CALL_FUNC_WITHOUT_GVL(GVL_FUNC(GetImageChannelMean), &args);
#endif
    CHECK_EXCEPTION();

    DestroyExceptionInfo(exception);

    ary = rb_ary_new2(2);
    rb_ary_store(ary, 0, rb_float_new(mean));
    rb_ary_store(ary, 1, rb_float_new(stddev));

    RB_GC_GUARD(ary);

    return ary;
}