The fused HDR projections at 0°, 90°, 180°, and 270°.

<p>The fused HDR projections at 0°, 90°, 180°, and 270°.</p

The processed gray figure about 90kV and 100kV.

<p>That has excluded the non-interesting area (overexposed area and “strip-like” noise).</p

Slices of reconstruction image with small cone angle.

<p>Slices of reconstruction image with small cone angle.</p

Slices of reconstruction image with larger cone angle.

<p>Slices of reconstruction image with larger cone angle.</p

The experiment CT system.

<p>This system is composed by X-ray (GE ISOVOLT 450KV) and detector (VARIAN PaxScan2520).</p

CT images obtained using the improved fused images.

<p>The first row CT image from left to right is corresponding to bottom, center and top about workpiece, The second row is respectively the gray curve at the indicated line. Relative to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141789#pone.0141789.g008" target="_blank">Fig 8</a>, image quality and noise have major improvement</p

The corresponding gray figure between 90kV and 100 kV at 0°.

<p>Horizontal axis represents the gray of one tube-voltage image, and vertical axis represents the next tube-voltage. These points represent the gray of one point about object in the adjacent two frames images.</p

Geometrical relationship between a ray and an object.

<p>Geometrical relationship between a ray and an object.</p

The image sequences collected at varying energies.

<p>Each row corresponds to a different projection angle (0° and 90°), and each column corresponds to a different transillumination voltage (60 kV, 70 kV, 80 kV, 90 kV, and 100 kV).</p

The principle of HDR-CT imaging.

<p>For the complicated components, get multi-voltage sequences at one projection angle, which are responding to different thickness. Then by HDR fusion and CT reconstruction, get the full information.</p