How can to resize an image uploaded in to the smart image

Hi

   I got a reference for the same question from Stack Overflow http://stackoverflow.com/questions/14726485/resize-an-image-resource-in-cq5/16728970#16728 970

I tried the same method

Resource resourceNew = resource.getResourceResolver().getResource(img.getFileReference());

    Asset asset = resourceNew.adaptTo(Asset.class);

    log.error("asset ****" + asset);

    Layer layer = new Layer(asset.getOriginal().getStream());

    layer.resize(200, 200);

    log.error("layer ****" + layer);

                        Image image = new Image(resource);

    String mimeType = image.getMimeType();

    ByteArrayOutputStream bout = null;

    ByteArrayInputStream bin = null;

    try {

        bout = new ByteArrayOutputStream(2048);

        layer.write(mimeType, 1, bout);

        bin = new ByteArrayInputStream(bout.toByteArray());

        asset.addRendition("resizedImage", bin, mimeType);

log.error("asset Bin" + asset);

    } finally {

        // close streams ...              

    }

Where img is my Image object and I was able to create a rendition in the dam.

But the rendition I am getting is in File format. Is there a way by which i can change it to png format??? any Help will be appreciable..

Thanks

Veena