Handle 16-bit PNGs

vips.go

@@ -55,6 +55,8 @@ type vipsSaveOptions struct {
 	Interlace      bool
 	NoProfile      bool
 	Interpretation Interpretation
+	Flatten        bool
+	Background     Color
 }
 
 type vipsWatermarkOptions struct {
@@ -341,6 +343,15 @@ func vipsPreSave(image *C.VipsImage, o *vipsSaveOptions) (*C.VipsImage, error) {
 		image = outImage
 	}
 
+	// Flatten image on a background, if necessary
+	if o.Flatten {
+		var err error
+		if outImage, err = vipsFlattenBackground(image, o.Background); err != nil {
+			return nil, err
+		}
+		image = outImage
+	}
+
 	return image, nil
 }