public void setSuppressAlpha(boolean suppressAlpha) {
        this.suppressAlpha = suppressAlpha;
    }
If set, no alpha (transparency) channel will appear in the
output image.

<p> The default is to allow transparency to appear in the
output image.
plugins/svg-plugin/batik-codec-fix/src/main/java/org/apache/batik/ext/awt/image/codec/png/PNGDecodeParam.java