```
using DSLType = rtk::DrawSheppLoganFilter<OutputImageType, OutputImageType>;
DSLType::Pointer dsl2 = DSLType::New();
dsl2->InPlaceOff();
dsl2->SetInput(tomographySource->GetOutput());
dsl2->Update();
```

Because it is the design of the Shepp Logan! See chapter 3 of Kak & Slaney, figure 3.4b, the contrast in the center is 1%. This is designed to be a difficult reconstruction task. Not to be mixed with the modified high contrast version of the Shepp Logan in Matlab, see here which has been probably developed to make the task easier. This one is described in page 201 of â€śToft PA, SĂ¸rensen JA. The Radon Transform - Theory and Implementation. Kgs. Lyndgby, Denmark: Technical University of Denmark (DTU), 1996.â€ť It can be drawn with `rtk::DrawGeometricPhantomImageFilter`

using the following text file

```
// High contrast Shepp Logan phantom, idem as Matlab
[Ellipsoid] A=0.6900 B=0 C=0.9200 x=0 y=0 z=0 beta=0 gray=2.0
[Ellipsoid] A=0.6624 B=0 C=0.8740 x=0 y=0 z=-0.0184 beta=0 gray=-1.6
[Ellipsoid] A=0.1100 B=0 C=0.3100 x=0.22 y=0 z=0 beta=-18 gray=-0.4
[Ellipsoid] A=0.1600 B=0 C=0.4100 x=-0.22 y=0 z=0 beta=18 gray=-0.4
[Ellipsoid] A=0.2100 B=0 C=0.2500 x=0 y=0 z=0.35 beta=0 gray=0.2
[Ellipsoid] A=0.0460 B=0 C=0.0460 x=0 y=0 z=0.1 beta=0 gray=0.2
[Ellipsoid] A=0.0460 B=0 C=0.0460 x=0 y=0 z=-0.1 beta=0 gray=0.2
[Ellipsoid] A=0.0460 B=0 C=0.0230 x=-0.08 y=0 z=-0.605 beta=0 gray=0.2
[Ellipsoid] A=0.0230 B=0 C=0.0230 x=0 y=0 z=-0.606 beta=0 gray=0.2
[Ellipsoid] A=0.0230 B=0 C=0.0460 x=0.06 y=0 z=-0.605 beta=0 gray=0.2
```

1 Like

thank you