docs: public static PlanarImage convertRGBA2RGB(PlanarImage src) {
          ColorModel cm = src.getColorModel();
  
          // RGB并且为四通道， 删除掉alpha通道
          if (cm.getColorSpace().getType() == ColorSpace.TYPE_RGB && src.getNumBands() == 4) {
              if(!cm.getColorSpace().isCS_sRGB()) {
                  src = generalColorConvert(src);
              }
              
              ParameterBlock pb = new ParameterBlock();
              int[] bitsRGB = { 8, 8, 8 };
              ColorSpace sRGB = ColorSpace.getInstance(ColorSpace.CS_sRGB);
              ColorModel cmRGB = new ComponentColorModel(sRGB, bitsRGB, false, false, Transparency.OPAQUE,
                                                         DataBuffer.TYPE_BYTE);
              ImageLayout il = new ImageLayout();
  
              il.setColorModel(cmRGB);
  
              RenderingHints rh = new RenderingHints(JAI.KEY_IMAGE_LAYOUT, il);
  
              il.setSampleModel(cmRGB.createCompatibleSampleModel(src.getTileWidth(), src.getTileHeight()));
              pb = new ParameterBlock();
              pb.addSource(src);
              src = JAI.create("format", pb, rh);
          }
  
          return src;
      }