@Override
    public WriteCellData<?> convertToExcelData(String value, ExcelContentProperty contentProperty,
                                               GlobalConfiguration globalConfiguration) throws IOException {
        return new WriteCellData<>(FileUtils.readFileToByteArray(new File(value)));
    }
String and image converter

@author Jiaju Zhuang
fastexcel-core/src/main/java/cn/idev/excel/converters/string/StringImageConverter.java