GH-OS fixed, demos updated, add_artifacts function

1 files changed, 33 insertions, 0 deletions

diff --git a/supp/sino_add_artifacts.m b/supp/sino_add_artifacts.m
new file mode 100644
index 0000000..f601914
--- /dev/null
+++ b/supp/sino_add_artifacts.m
@@ -0,0 +1,33 @@
+function sino_artifacts = sino_add_artifacts(sino,artifact_type)
+% function to add various distortions to the sinogram space, current
+% version includes: random rings and zingers (streaks)
+% Input: 
+% 1. sinogram
+% 2. artifact type: 'rings' or 'zingers' (streaks)
+
+
+[Detectors, anglesNumb, SlicesZ] = size(sino);
+fprintf('%s %i %s %i %s %i %s \n', 'Sinogram has a dimension of', Detectors, 'detectors;', anglesNumb, 'projections;', SlicesZ, 'vertical slices.');
+
+sino_artifacts = sino;
+
+if (strcmp(artifact_type,'rings'))
+    fprintf('%s \n', 'Adding rings...');    
+    NumRings = round(Detectors/20); % Number of rings relatively to the size of Detectors
+    IntenOff = linspace(0.05,0.5,NumRings); % the intensity of rings in the selected range
+    
+    for k = 1:SlicesZ
+        % generate random indices to propagate rings
+        RandInd = randperm(Detectors,Detectors);
+        for jj = 1:NumRings
+            ind_c = RandInd(jj);
+            sino_artifacts(ind_c,1:end,k) = sino_artifacts(ind_c,1:end,k) + IntenOff(jj).*sino_artifacts(ind_c,1:end,k); % generate a constant offset            
+        end
+        
+    end
+elseif (strcmp(artifact_type,'zingers'))
+    fprintf('%s \n', 'Adding zingers...');
+else
+    fprintf('%s \n', 'Nothing selected, the same sinogram returned...');
+end
+end
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