demoAccessLossy.sch

<?xml version="1.0"?>
<!--
   Schematron jpylyzer schema: verify if JP2 conforms to 
   a lossily compressed profile for access copies
   Johan van der Knijff, KB / National Library of the Netherlands , 3 September 2012.
   Based on original schema by Adam Retter, The National Archives
   For demonstration purposes only!
-->

<s:schema xmlns:s="http://purl.oclc.org/dsdl/schematron">
  <s:pattern>
    <s:title>Lossy access JP2 check</s:title>

    <!-- check that the jpylyzer element exists -->
    <s:rule context="/">
    <s:assert test="jpylyzer">no jpylyzer element found</s:assert>
    </s:rule>

    <!-- check that isValidJP2 element exists with the text 'True' -->
    <s:rule context="/jpylyzer">
    <s:assert test="isValidJP2 = 'True'">no valid JP2</s:assert>
    </s:rule>

    <!-- Top-level properties checks -->

    <s:rule context="/jpylyzer/properties">

    <!-- check if XML box exists -->
    <s:assert test="xmlBox">no XML box</s:assert>

    <!-- check if compression ratio doesn't exceed threshold value (a bit tricky as for images that 
         don't contain much information very high compression ratios may be obtained without losing quality)  
          -->
    <s:assert test="compressionRatio &lt; 35">Too much compression</s:assert>
    </s:rule>

    <!-- check if resolution box exists -->
    <s:rule context="/jpylyzer/properties/jp2HeaderBox">
    <s:assert test="resolutionBox">no resolution box</s:assert>
    </s:rule>

    <!-- check if resolution box contains capture resolution box -->
    <s:rule context="/jpylyzer/properties/jp2HeaderBox/resolutionBox">
    <s:assert test="captureResolutionBox">no capture resolution box</s:assert>
    </s:rule>

    <!-- check that METH equals 'Restricted ICC' -->
    <s:rule context="/jpylyzer/properties/jp2HeaderBox/colourSpecificationBox">
      <s:assert test="meth = 'Restricted ICC'">METH not 'Restricted ICC'</s:assert>
    </s:rule>

    <!-- check X- and Y- tile sizes -->
    <s:rule context="/jpylyzer/properties/contiguousCodestreamBox/siz">
    <s:assert test="xTsiz = '1024'">wrong X Tile size</s:assert>
    <s:assert test="yTsiz = '1024'">wrong Y Tile size</s:assert>
    </s:rule>

    <!-- checks on codestream COD parameters -->
    <s:rule context="/jpylyzer/properties/contiguousCodestreamBox/cod">

    <!-- Precincts -->
    <s:assert test="precincts = 'yes'">no precincts</s:assert>
 
    <!-- Error resilience features: sop, eph and segmentation symbols -->
    <s:assert test="sop = 'yes'">no start-of-packet headers</s:assert>
    <s:assert test="eph = 'yes'">no end-of-packet headers</s:assert>
    <s:assert test="segmentationSymbols = 'yes'">no segmentation symbols</s:assert>

    <!-- Progression order -->
    <s:assert test="order = 'RPCL'">wrong progression order</s:assert>

    <!-- Layers -->
    <s:assert test="layers = '8'">wrong number of layers</s:assert>

    <!-- Colour transformation (only for RGB images, i.e. number of components = 3)-->
    <s:assert test="(multipleComponentTransformation = 'yes') and (../../jp2HeaderBox/imageHeaderBox/nC = '3') 
         or (multipleComponentTransformation = 'no') and (../../jp2HeaderBox/imageHeaderBox/nC = '1')">
                     no colour transformation</s:assert>

    <!-- Decomposition levels -->
    <s:assert test="levels = '5'">wrong number of decomposition levels</s:assert>

    <!-- Codeblock size -->
    <s:assert test="codeBlockWidth = '64'">wrong codeblock width</s:assert>
    <s:assert test="codeBlockHeight = '64'">wrong codeblock height</s:assert>

    <!-- Transformation (lossy vs lossless) -->
    <s:assert test="transformation = '9-7 irreversible'">wrong transformation</s:assert>

    <!-- checks on X- and Y- precinct sizes: 256x256 for 2 highest resolution levels,
         128x128 for remaining ones  -->
    <s:assert test="precinctSizeX[1] = '128'">precinctSizeX doesn't match profile</s:assert>
    <s:assert test="precinctSizeX[2] = '128'">precinctSizeX doesn't match profile</s:assert>
    <s:assert test="precinctSizeX[3] = '128'">precinctSizeX doesn't match profile</s:assert>
    <s:assert test="precinctSizeX[4] = '128'">precinctSizeX doesn't match profile</s:assert>
    <s:assert test="precinctSizeX[5] = '256'">precinctSizeX doesn't match profile</s:assert>
    <s:assert test="precinctSizeX[6] = '256'">precinctSizeX doesn't match profile</s:assert>
    <s:assert test="precinctSizeY[1] = '128'">precinctSizeY doesn't match profile</s:assert>
    <s:assert test="precinctSizeY[2] = '128'">precinctSizeY doesn't match profile</s:assert>
    <s:assert test="precinctSizeY[3] = '128'">precinctSizeY doesn't match profile</s:assert>
    <s:assert test="precinctSizeY[4] = '128'">precinctSizeY doesn't match profile</s:assert>
    <s:assert test="precinctSizeY[5] = '256'">precinctSizeY doesn't match profile</s:assert>
    <s:assert test="precinctSizeY[6] = '256'">precinctSizeY doesn't match profile</s:assert>
    </s:rule>

  </s:pattern>
</s:schema>