ith jab data of all samples under test SPD (scaled to &#39;unit&#39; circle)</span>
<span class="sd">            | If not None: plot chromaticity coordinates of test samples relative to </span>
<span class="sd">            | the mean chromaticity of the samples under the reference illuminant.</span>
<span class="sd">        :jabri: </span>
<span class="sd">            | None, optional</span>
<span class="sd">            | ndarray with jab data of all samples under reference SPD (scaled to &#39;unit&#39; cir