Method: Magick::Image#channel

Defined in:
ext/RMagick/rmimage.cpp

#channel(channel_arg) ⇒ Magick::Image

Extract a channel from the image. A channel is a particular color component of each pixel in the image.

Parameters:

  • channel_arg (Magick::ChannelType) —

    the type of the channel to extract

Returns:



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# File 'ext/RMagick/rmimage.cpp', line 2405

VALUE
Image_channel(VALUE self, VALUE channel_arg)
{
    Image *image, *new_image;
    ChannelType channel;
#if defined(IMAGEMAGICK_7)
    ExceptionInfo *exception;
#endif

    image = rm_check_destroyed(self);

    VALUE_TO_ENUM(channel_arg, channel, ChannelType);

#if defined(IMAGEMAGICK_7)
    exception = AcquireExceptionInfo();
    GVL_STRUCT_TYPE(SeparateImage) args = { image, channel, exception };
    new_image = (Image *)CALL_FUNC_WITHOUT_GVL(GVL_FUNC(SeparateImage), &args);
    rm_check_exception(exception, new_image, DestroyOnError);
    DestroyExceptionInfo(exception);
#else
    new_image = rm_clone_image(image);
    GVL_STRUCT_TYPE(SeparateImageChannel) args = { new_image, channel };
    CALL_FUNC_WITHOUT_GVL(GVL_FUNC(SeparateImageChannel), &args);

    rm_check_image_exception(new_image, DestroyOnError);
#endif

    return rm_image_new(new_image);
}