Method: Magick::Image#clut_channel

Defined in:
ext/RMagick/rmimage.cpp

#clut_channel(clut_image, channel = Magick::AllChannels) ⇒ Magick::Image #clut_channel(clut_image, *channels) ⇒ Magick::Image

Replace the channel values in the target image with a lookup of its replacement value in an LUT gradient image.

The LUT image should be either a single row or column image of replacement colors. The lookup is controlled by the -interpolate setting, especially for an LUT which is not the full length needed by the IM installed Quality (Q) level. Good settings for this is the default ‘bilinear’ or ‘bicubic’ interpolation setting for a smooth color gradient, or ‘integer’ for a direct unsmoothed lookup of color values.

This method is especially suited to replacing a grayscale image with specific color gradient from the CLUT image.

Overloads:

  • #clut_channel(clut_image, channel = Magick::AllChannels) ⇒ Magick::Image

    Parameters:

    • clut_image (Magick::Image, Magick::ImageList) —

      The LUT gradient image.

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

      a ChannelType arguments.

  • #clut_channel(clut_image, *channels) ⇒ Magick::Image

    Parameters:

Returns:



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# File 'ext/RMagick/rmimage.cpp', line 2772

VALUE
Image_clut_channel(int argc, VALUE *argv, VALUE self)
{
    Image *image, *clut;
    ChannelType channels;
    MagickBooleanType okay;
#if defined(IMAGEMAGICK_7)
    ExceptionInfo *exception;
#endif

    image = rm_check_frozen(self);

    // check_destroyed before confirming the arguments
    if (argc >= 1)
    {
        clut = rm_check_destroyed(rm_cur_image(argv[0]));
        channels = extract_channels(&argc, argv);
        if (argc != 1)
        {
            rb_raise(rb_eArgError, "wrong number of arguments (%d for 1 or more)", argc);
        }
    }
    else
    {
        rb_raise(rb_eArgError, "wrong number of arguments (%d for 1 or more)", argc);
    }

#if defined(IMAGEMAGICK_7)
    exception = AcquireExceptionInfo();
    BEGIN_CHANNEL_MASK(image, channels);
    GVL_STRUCT_TYPE(ClutImage) args = { image, clut, image->interpolate, exception };
    void *ret = CALL_FUNC_WITHOUT_GVL(GVL_FUNC(ClutImage), &args);
    okay = static_cast<MagickBooleanType>(reinterpret_cast<intptr_t &>(ret));
    END_CHANNEL_MASK(image);
    CHECK_EXCEPTION();
    DestroyExceptionInfo(exception);
#else
    GVL_STRUCT_TYPE(ClutImageChannel) args = { image, channels, clut };
    void *ret = CALL_FUNC_WITHOUT_GVL(GVL_FUNC(ClutImageChannel), &args);
    okay = static_cast<MagickBooleanType>(reinterpret_cast<intptr_t &>(ret));
    rm_check_image_exception(image, RetainOnError);
    rm_check_image_exception(clut, RetainOnError);
#endif
    if (!okay)
    {
        rb_raise(rb_eRuntimeError, "ClutImageChannel failed.");
    }

    return self;
}