src/java.desktop/share/classes/com/sun/imageio/plugins/png/PNGMetadata.java

*** 1880,1889 ****
--- 1880,1890 ----
                          int blue = getIntAttribute(child, "blue");
                          if (red == green && red == blue) {
                              bKGD_colorType = PNGImageReader.PNG_COLOR_GRAY;
                              bKGD_gray = red;
                          } else {
+                             bKGD_colorType = PNGImageReader.PNG_COLOR_RGB;
                              bKGD_red = red;
                              bKGD_green = green;
                              bKGD_blue = blue;
                          }
                          bKGD_present = true;