public void setGamma(float gamma) {
        this.gamma = gamma;
        gammaSet = true;
    }
Sets the file gamma value for the image.

<p> The 'gAMA' chunk will encode this information.
plugins/svg-plugin/batik-codec-fix/src/main/java/org/apache/batik/ext/awt/image/codec/png/PNGEncodeParam.java