public void setExpandPalette(boolean expandPalette) {
        this.expandPalette = expandPalette;
    }
If set, palette color images (PNG color type 3) will
be decoded into full-color (RGB) output images.  The output
image may have 3 or 4 channels, depending on the presence of
transparency information.

<p> The default is to output palette images using a single
channel.  The palette information is used to construct the
output image's <code>ColorModel</code>.
plugins/svg-plugin/batik-codec-fix/src/main/java/org/apache/batik/ext/awt/image/codec/png/PNGDecodeParam.java