JMuPDF BufferedImage color problem

test.rb

require 'java'
require 'lib/jmupdf.jar'

java_import com.jmupdf.pdf.PdfDocument
java_import com.jmupdf.exceptions.DocException;
java_import com.jmupdf.exceptions.DocSecurityException;
java_import com.jmupdf.page.Page;
java_import com.jmupdf.page.PageRenderer;
java_import java.awt.image.BufferedImage;

pdf_file = PdfDocument.new(File.read('pdf/test1.pdf').to_java_bytes)

render = PageRenderer.new(1,0, PageRenderer::IMAGE_TYPE_RGB)
render.setPage(pdf_file.get_page(1))
render.render(true)
bufferedImage1 = render.get_image

os = java.io.ByteArrayOutputStream.new
javax.imageio.ImageIO.write(render.get_image, "JPG", os)
File.open('jmupdf-03-buffered-image-04.jpg', 'w') {|f| f.write(String.from_java_bytes(os.to_byte_array)) }