This is how I did this. From the Script Assertion of the http GET request. Hope It helps someone.
def ins = context.httpResponse.getRawResponseBody(); def isImageSaved = false; InputStream inputStream; FileOutputStream outputStream; if (ins){ try { inputStream = new ByteArrayInputStream(ins); outputStream = new FileOutputStream(new File(context.expand("C:\\animal.jpg"))); int read = 0; byte[] bytes = new byte[1024]; while ((read = inputStream.read(bytes)) != -1) { outputStream.write(bytes, 0, read); } isImageSaved = true; }catch (Exception e){ log.error e; e.printStackTrace(); }finally{ inputStream.close(); outputStream.close(); } } else { log.error "image does not exist..."; } context.testCase.setPropertyValue("isImageSaved", isImageSaved.inspect());