Hi Swaminathan,
Thank you for your inquiry.
This is to update you that Aspose.OCR is an API that can perform OCR & OMR operations on images. You have to provide an image or scanned OMR sheet image to the API. It will not help you get PNG image out of scanner.
Hope the above information helps. If above is not the case, please feel free to contact us with more details along with sample. We will look into it and update you accordingly.