Image Comparison Results

The following XML shows a single record produced by image comparison.

<output>
  <record>
    <pageNumber>1</pageNumber>
    <trackname>Compare.Result</trackname>
    <ImageComparisonResult>
      <id>60480c72-fa13-401d-92e6-e7ec87eb3e13</id>
      <identity>
        <identifier>Camera39</identifier>
        <database>ReferenceImages</database>
        <imagelabel>4132cf6ee5bcff7b03037140767ff32c</imagelabel>
        <metadata>
          <item>
            <key>Location</key>
            <value>Cambridge</value>
          </item>
        </metadata>
      </identity>
      <imageChangeScore>19.27</imageChangeScore>
      <changedRegion>
        <region>
          <left>40</left>
          <top>8</top>
          <width>40</width>
          <height>40</height>
        </region>
        <score>82.72</score>
      </changedRegion>
      <changedRegion>
        <region>
          <left>80</left>
          <top>8</top>
          <width>40</width>
          <height>40</height>
        </region>
        <score>30.14</score>
      </changedRegion>
      ...
</output>

The record contains the following information:

  • The identity element describes the reference image (in your training database) that was used for comparison. Media Server creates a separate record for each reference that the ingested image was compared to.

    • The identifier element provides the identifier of the reference.
    • The database element provides the name of the database in which the reference exists.
    • The imagelabel element provides the label of the reference image that was used for comparison.
    • The metadata element provides metadata that you associated with the reference when you trained Media Server. If there is no metadata in the training database, this element is omitted.
  • The imageChangeScore element indicates the amount of change between the images. This value is a percentage, between zero (no changes) and 100 (every region has significant changes).
  • Each changedRegion element describes a change between the reference image (in the training database) and the source image (that was analyzed). If there are no differences, there will be no changedRegion elements present. Each changedRegion element describes a small part of the image.

    • The region element describes the position of the top-left corner of the region, and its width and height. The region refers to the source image, not the reference image. This is particularly important in cases where the source media is a different size to your reference image. If you set the region configuration parameter to analyze only part of the source media, the co-ordinates 0,0 still refer to the top-left corner of the full source media.
    • The score element specifies how much the region has changed, as a percentage from zero to 100. A high score indicates that there are major changes within the region and a low score indicates minor differences. You can use the scores to locate the regions that show the greatest change.