Method: Magick::Image#convolve

Defined in:
ext/RMagick/rmimage.cpp

#convolve(order_arg, kernel_arg) ⇒ Magick::Image

Apply a custom convolution kernel to the image.

Parameters:

  • order_arg (Numeric) —

    the number of rows and columns in the kernel

  • kernel_arg (Array<Float>) —

    An ‘order*order` matrix of Float values.

Returns:



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# File 'ext/RMagick/rmimage.cpp', line 4812

VALUE
Image_convolve(VALUE self, VALUE order_arg, VALUE kernel_arg)
{
    Image *image, *new_image;
    size_t order;
    ExceptionInfo *exception;
#if defined(IMAGEMAGICK_7)
    KernelInfo *kernel;
#else
    double *kernel;
    unsigned int x;
#endif

    image = rm_check_destroyed(self);

    if (NUM2INT(order_arg) <= 0)
    {
        rb_raise(rb_eArgError, "order must be non-zero and positive");
    }

    order = NUM2INT(order_arg);
    kernel_arg = rb_Array(kernel_arg);
    rm_check_ary_len(kernel_arg, (long)(order*order));

#if defined(IMAGEMAGICK_7)
    kernel = convolve_create_kernel_info(order, kernel_arg);
#else
    // Convert the kernel array argument to an array of doubles

    kernel = (double *)ALLOC_N(double, order*order);
    for (x = 0; x < (unsigned)(order * order); x++)
    {
        VALUE element = rb_ary_entry(kernel_arg, (long)x);
        if (rm_check_num2dbl(element))
        {
            kernel[x] = NUM2DBL(element);
        }
        else
        {
            xfree((void *)kernel);
            rb_raise(rb_eTypeError, "type mismatch: %s given", rb_class2name(CLASS_OF(element)));
        }
    }
#endif

    exception = AcquireExceptionInfo();

#if defined(IMAGEMAGICK_7)
    GVL_STRUCT_TYPE(ConvolveImage) args = { image, kernel, exception };
    new_image = (Image *)CALL_FUNC_WITHOUT_GVL(GVL_FUNC(ConvolveImage), &args);
    DestroyKernelInfo(kernel);
#else
    GVL_STRUCT_TYPE(ConvolveImage) args = { image, order, kernel, exception };
    new_image = (Image *)CALL_FUNC_WITHOUT_GVL(GVL_FUNC(ConvolveImage), &args);
    xfree((void *)kernel);
#endif

    rm_check_exception(exception, new_image, DestroyOnError);
    DestroyExceptionInfo(exception);

    return rm_image_new(new_image);
}