{"action":"created","issue":{"url":"https://api.github.com/repos/MRtrix3/mrtrix3/issues/771","repository_url":"https://api.github.com/repos/MRtrix3/mrtrix3","labels_url":"https://api.github.com/repos/MRtrix3/mrtrix3/issues/771/labels{/name}","comments_url":"https://api.github.com/repos/MRtrix3/mrtrix3/issues/771/comments","events_url":"https://api.github.com/repos/MRtrix3/mrtrix3/issues/771/events","html_url":"https://github.com/MRtrix3/mrtrix3/issues/771","id":174671611,"number":771,"title":"dwidenoise: Don't skip edge voxels","user":{"login":"Lestropie","id":5637955,"avatar_url":"https://avatars2.githubusercontent.com/u/5637955?v=4","gravatar_id":"","url":"https://api.github.com/users/Lestropie","html_url":"https://github.com/Lestropie","followers_url":"https://api.github.com/users/Lestropie/followers","following_url":"https://api.github.com/users/Lestropie/following{/other_user}","gists_url":"https://api.github.com/users/Lestropie/gists{/gist_id}","starred_url":"https://api.github.com/users/Lestropie/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Lestropie/subscriptions","organizations_url":"https://api.github.com/users/Lestropie/orgs","repos_url":"https://api.github.com/users/Lestropie/repos","events_url":"https://api.github.com/users/Lestropie/events{/privacy}","received_events_url":"https://api.github.com/users/Lestropie/received_events","type":"User","site_admin":false},"labels":[{"id":96478022,"url":"https://api.github.com/repos/MRtrix3/mrtrix3/labels/enhancement","name":"enhancement","color":"84b6eb","default":true}],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2016-09-02T03:12:26Z","updated_at":"2017-08-08T07:00:00Z","closed_at":null,"body":"At the outer edges of the volume, where the kernel window centred at the voxel of interest is partly outside the image FoV, currently those voxels are skipped during denoising.\n\nInstead, define a 'fattening' window that extends further along those axes that are not constrained by the image FoV, in order to provide a comparable total number of voxels within the 'fattened' kernel to that of the standard cubic kernel. This ensures that the kernel window is still unique for each voxel in the image.\n"},"comment":{"url":"https://api.github.com/repos/MRtrix3/mrtrix3/issues/comments/320868317","html_url":"https://github.com/MRtrix3/mrtrix3/issues/771#issuecomment-320868317","issue_url":"https://api.github.com/repos/MRtrix3/mrtrix3/issues/771","id":320868317,"user":{"login":"Lestropie","id":5637955,"avatar_url":"https://avatars2.githubusercontent.com/u/5637955?v=4","gravatar_id":"","url":"https://api.github.com/users/Lestropie","html_url":"https://github.com/Lestropie","followers_url":"https://api.github.com/users/Lestropie/followers","following_url":"https://api.github.com/users/Lestropie/following{/other_user}","gists_url":"https://api.github.com/users/Lestropie/gists{/gist_id}","starred_url":"https://api.github.com/users/Lestropie/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Lestropie/subscriptions","organizations_url":"https://api.github.com/users/Lestropie/orgs","repos_url":"https://api.github.com/users/Lestropie/repos","events_url":"https://api.github.com/users/Lestropie/events{/privacy}","received_events_url":"https://api.github.com/users/Lestropie/received_events","type":"User","site_admin":false},"created_at":"2017-08-08T07:00:00Z","updated_at":"2017-08-08T07:00:00Z","body":"Had a change of thought process on how to do this, figured I'd write it down.\r\n\r\nUltimately one wants a set of nearby voxels for which the noise level is comparable. The cubic sliding window is just one way of doing this; but how best to deal with voxels near the edge of the FoV is ambiguous (could be done, but there's a few alternatives). A more precise expression of \"nearby\" voxels would be a *spherical* kernel, of an appropriate radius to capture an appropriate number of voxels within the kernel. This has two advantages:\r\n\r\n- It intrinsically works better with anisotropic voxels, since expansion of the voxel selection could be done in scanner space rather than being a fixed number of voxels per spatial axis.\r\n\r\n- When near the image FoV edge, simply continue expanding the selection radius until an appropriate number of image voxels has been included in the kernel."}}
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