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  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher-id">109</journal-id>
      <journal-id journal-id-type="index">urn:lsid:arphahub.com:pub:3dc5f44e-8666-58db-bc76-a455210e8891</journal-id>
      <journal-title-group>
        <journal-title xml:lang="en">JUCS - Journal of Universal Computer Science</journal-title>
        <abbrev-journal-title xml:lang="en">jucs</abbrev-journal-title>
      </journal-title-group>
      <issn pub-type="ppub">0948-695X</issn>
      <issn pub-type="epub">0948-6968</issn>
      <publisher>
        <publisher-name>Journal of Universal Computer Science</publisher-name>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="doi">10.3217/jucs-021-12-1536</article-id>
      <article-id pub-id-type="publisher-id">23749</article-id>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Research Article</subject>
        </subj-group>
        <subj-group subj-group-type="scientific_subject">
          <subject>E.3 - DATA ENCRYPTION</subject>
          <subject>H.3.5 - Online Information Services</subject>
          <subject>I.4 - IMAGE PROCESSING AND COMPUTER VISION</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>On Real-valued Visual Cryptographic Basis Matrices</article-title>
      </title-group>
      <contrib-group content-type="authors">
        <contrib contrib-type="author" corresp="yes">
          <name name-style="western">
            <surname>Buckley</surname>
            <given-names>Neil</given-names>
          </name>
          <email xlink:type="simple">08008783@hope.ac.uk</email>
          <xref ref-type="aff" rid="A1">1</xref>
        </contrib>
        <contrib contrib-type="author" corresp="no">
          <name name-style="western">
            <surname>Nagar</surname>
            <given-names>Atulya K.</given-names>
          </name>
          <xref ref-type="aff" rid="A1">1</xref>
        </contrib>
        <contrib contrib-type="author" corresp="no">
          <name name-style="western">
            <surname>Arumugam</surname>
            <given-names>Subramanian</given-names>
          </name>
          <xref ref-type="aff" rid="A2">2</xref>
        </contrib>
      </contrib-group>
      <aff id="A1">
        <label>1</label>
        <addr-line content-type="verbatim">Liverpool Hope University, Liverpool, United Kingdom</addr-line>
        <institution>Liverpool Hope University</institution>
        <addr-line content-type="city">Liverpool</addr-line>
        <country>United Kingdom</country>
      </aff>
      <aff id="A2">
        <label>2</label>
        <addr-line content-type="verbatim">Kalasalingam University, Anand Nagar, India</addr-line>
        <institution>Kalasalingam University</institution>
        <addr-line content-type="city">Anand Nagar</addr-line>
        <country>India</country>
      </aff>
      <author-notes>
        <fn fn-type="corresp">
          <p>Corresponding author: Neil Buckley (<email xlink:type="simple">08008783@hope.ac.uk</email>).</p>
        </fn>
        <fn fn-type="edited-by">
          <p>Academic editor: </p>
        </fn>
      </author-notes>
      <pub-date pub-type="collection">
        <year>2015</year>
      </pub-date>
      <pub-date pub-type="epub">
        <day>01</day>
        <month>11</month>
        <year>2015</year>
      </pub-date>
      <volume>21</volume>
      <issue>12</issue>
      <fpage>1536</fpage>
      <lpage>1562</lpage>
      <uri content-type="arpha" xlink:href="http://openbiodiv.net/5A33C812-D22C-5EDB-A584-4B98DC696F94">5A33C812-D22C-5EDB-A584-4B98DC696F94</uri>
      <uri content-type="zenodo_dep_id" xlink:href="https://zenodo.org/record/5505857">5505857</uri>
      <history>
        <date date-type="received">
          <day>02</day>
          <month>03</month>
          <year>2015</year>
        </date>
        <date date-type="accepted">
          <day>11</day>
          <month>11</month>
          <year>2015</year>
        </date>
      </history>
      <permissions>
        <copyright-statement>Neil Buckley, Atulya K. Nagar, Subramanian Arumugam</copyright-statement>
        <license license-type="creative-commons-attribution" xlink:href="" xlink:type="simple">
          <license-p>This article is freely available under the J.UCS Open Content License.</license-p>
        </license>
      </permissions>
      <abstract>
        <label>Abstract</label>
        <p>Visual cryptography (VC) encodes an image into noise-like shares, which can be stacked to reveal a reduced quality version of the original. The problem with encrypting colour images is that they must undergo heavy pre-processing to reduce them to binary, entailing significant quality loss. This paper proposes VC that works directly on intermediate grayscale values per colour channel and demonstrates real-valued basis matrices for this purpose. The resulting stacked shares produce a clearer reconstruction than in binary VC, and to the best of the authors' knowledge, is the first method posing no restrictions on colour values while maintaining the ability to decrypt with human vision. Grayscale and colour images of differing entropies are encrypted using fuzzy OR and XOR, and their PSNR and structural similarities are compared with binary VC to demonstrate improved quality. It is compared with previous research and its advantages highlighted, notably in high quality reconstructions with minimal processing.</p>
      </abstract>
    </article-meta>
  </front>
</article>
