<span class="Apple-style-span" style="font-family: arial, sans-serif; font-size: 13px; border-collapse: collapse; ">Hi All,<div><br></div><div>I am new to ITK and I am working on PET-CT registration. I have a PET image dataset which has a very low resolution, whereas my CT image dataset is of very high resolution. Before I run my registration algorithm, I want to resample/resize my PET images to match the resolution of the CT images. However, any resizing of the PET image is bringing in excessive noise in the image, even with BSpline interpolation. Also, I notice that if I don't resize the image at all, the output image still has significant noise. Therefore I think I must be missing something in my code. I have tried the Similarity2DTransform, the AffineTransform. My code goes somewhat like this:</div>
<div><br></div><div><div> typedef itk::ResampleImageFilter <InputImageType, OutputImageType> FilterType;</div><div><span style="white-space: pre; "> </span>FilterType::Pointer filter = FilterType::New();</div>
<div><br></div><div><span style="white-space: pre; "> </span>typedef itk::AffineTransform <double, Dimension> TransformType;</div><div><span style="white-space: pre; "> </span>TransformType::Pointer transform = TransformType::New();</div>
<div><span style="white-space: pre; "> </span>filter->SetTransform(transform);</div><div><br></div><div><span style="white-space: pre; "> </span>typedef itk::BSplineInterpolateImageFunction <InputImageType, double> InterpolatorType;</div>
<div><span style="white-space: pre; "> </span>InterpolatorType::Pointer interpolator = InterpolatorType::New();</div><div><span style="white-space: pre; "> </span>filter->SetInterpolator ( interpolator );</div><div>
<br>
</div><div><span style="white-space: pre; "> </span>double spacing[Dimension];</div><div><span style="white-space: pre; "> </span>spacing[0] = 1.0; // pixel spacing in millimeters along X</div><div><span style="white-space: pre; "> </span>spacing[1] = 1.0; // pixel spacing in millimeters along Y</div>
<div><span style="white-space: pre; "> </span>filter->SetOutputSpacing ( spacing );</div><div><br></div><div><span style="white-space: pre; "> </span>double origin[Dimension];</div><div><span style="white-space: pre; "> </span>origin[0] = -500; // X space coordinate of origin</div>
<div><span style="white-space: pre; "> </span>origin[1] = -500; // Y space coordinate of origin</div><div><span style="white-space: pre; "> </span>filter->SetOutputOrigin ( origin );</div><div><br></div><div><span style="white-space: pre; "> </span>InputImageType::DirectionType direction;</div>
<div><span style="white-space: pre; "> </span>direction.SetIdentity();</div><div><span style="white-space: pre; "> </span>direction = inputImage->GetDirection();</div><div><br></div><div><span style="white-space: pre; "> </span>InputImageType::SizeType size;</div>
<div><br></div><div><span style="white-space: pre; "> </span>size[0] = 1000; // number of pixels along X</div><div><span style="white-space: pre; "> </span>size[1] = 1000; // number of pixels along Y</div><div><br></div>
<div><span style="white-space: pre; "> </span>filter->SetSize(size);</div><div><br></div><div>What I am looking to do is get the PET image to look like when we zoom into the image using a image viewer like IrfanView.</div>
<div><br></div><div>Any suggestions will be of great help.</div><div><br></div><div>Thanks,</div><div>Abhik Datta.</div></div></span>