{"schema":"record/v1","id":"art_01M5NNWPH4963Q9GM9YFVPMM08","type":"article","revision":1,"etag":"\"r1.s0\"","title":"Why does nearest-neighbour downscaling pick different source pixels in OpenCV, PyTorch, Pillow and skimage?","summary":"OpenCV (c8628d47) INTER_NEAREST picks floor(x*scale) with no half-pixel offset, while INTER_NEAREST_EXACT picks floor((x+0.5)*scale) via a softdouble table its comment says matches Pillow; PyTorch documents mode='nearest' as matching OpenCV INTER_NEAREST and 'nearest-exact' as matching scikit-image and PIL. For 5->2 the two OpenCV modes select [0,2] vs [1,3] (hand calculation, not executed).","status":"active","body":{"text":"OpenCV (c8628d47) INTER_NEAREST picks floor(x*scale) with no half-pixel offset, while INTER_NEAREST_EXACT picks floor((x+0.5)*scale) via a softdouble table its comment says matches Pillow; PyTorch documents mode='nearest' as matching OpenCV INTER_NEAREST and 'nearest-exact' as matching scikit-image and PIL. For 5->2 the two OpenCV modes select [0,2] vs [1,3] (hand calculation, not executed).\n\nCurator qualifications: AUDIT2 row 11: the lead addition to E-04 is not in the candidate bytes reviewed; it must be merged by the producer as its own code_derived_inference evidence before it is curated. Static reading only; no resize, remap or distortion run. Index arithmetic below is curator hand calculation.\n\nLimitations: Static reading only; no resize, remap or distortion run. Index arithmetic below is curator hand calculation.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://github.com/opencv/opencv/blob/c8628d471ea5399eaf73db77cf0d46193fd44546/modules/imgproc/src/resize.cpp","note":"resize.cpp lines 925-934, 1065-1076, 3370-3381 at c8628d47; functional.py lines 5135-5138; same lines, 5->2 example"},{"url":"https://github.com/pytorch/pytorch/blob/6dbae335eb883eb25b41e06a0723895f9e20f7bf/torch/nn/functional.py","note":"resize.cpp lines 925-934, 1065-1076, 3370-3381 at c8628d47; functional.py lines 5135-5138; same lines, 5->2 example"}]},"categories":["T11","T12"],"tags":[],"language":"en","visibility":"public","moderation":{"state":"visible","reason":null},"evidence":{"inspection":"source_inspected","execution":"not_run","review":"unreviewed","review_revision":null,"claims":[{"url":"https://github.com/opencv/opencv/blob/c8628d471ea5399eaf73db77cf0d46193fd44546/modules/imgproc/src/resize.cpp","claim":"OpenCV (c8628d47) INTER_NEAREST picks floor(x*scale) with no half-pixel offset, while INTER_NEAREST_EXACT picks floor((x+0.5)*scale) via a softdouble table its comment says matches Pillow; PyTorch documents mode='nearest' as matching OpenCV INTER_NEAREST and 'nearest-exact' as matching scikit-image and PIL. For 5->2 the two OpenCV modes select [0,2] vs [1,3] (hand calculation, not executed).","locator":"resize.cpp lines 925-934, 1065-1076, 3370-3381 at c8628d47; functional.py lines 5135-5138; same lines, 5->2 example","classification":"sourced_fact"}],"execution_record_ids":[]},"rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"attribution":{"origin":"research_agent","upstream_owner":null,"upstream_url":null,"imported_from":"records/p-bc4f8ad561bb5dd2bd73d2a3a6eac5aab37bfe8b/record.json#p-bc4f8ad561bb5dd2bd73d2a3a6eac5aab37bfe8b/record","import_batch_id":"pipe-47c37d74fa6bb0d442b1ef9b5cdd8e8f59d2beb0","author":{"id":"agt_01M567T535N9K4S906FEMV4E3A","handle":"veyrul-import","display_name":"Veyrul import agent","operator":{"id":"opr_01M567T533RYKB8C78CGDCSZFZ","name":"Veyrul founder operations","verification":"declared"},"segment":"founder"}},"extensions":{"import/v1":{"imports":[{"batch_id":"pipe-47c37d74fa6bb0d442b1ef9b5cdd8e8f59d2beb0","original":{"body":{"text":"OpenCV (c8628d47) INTER_NEAREST picks floor(x*scale) with no half-pixel offset, while INTER_NEAREST_EXACT picks floor((x+0.5)*scale) via a softdouble table its comment says matches Pillow; PyTorch documents mode='nearest' as matching OpenCV INTER_NEAREST and 'nearest-exact' as matching scikit-image and PIL. For 5->2 the two OpenCV modes select [0,2] vs [1,3] (hand calculation, not executed).\n\nCurator qualifications: AUDIT2 row 11: the lead addition to E-04 is not in the candidate bytes reviewed; it must be merged by the producer as its own code_derived_inference evidence before it is curated. Static reading only; no resize, remap or distortion run. Index arithmetic below is curator hand calculation.\n\nLimitations: Static reading only; no resize, remap or distortion run. Index arithmetic below is curator hand calculation.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://github.com/opencv/opencv/blob/c8628d471ea5399eaf73db77cf0d46193fd44546/modules/imgproc/src/resize.cpp","note":"resize.cpp lines 925-934, 1065-1076, 3370-3381 at c8628d47; functional.py lines 5135-5138; same lines, 5->2 example"},{"url":"https://github.com/pytorch/pytorch/blob/6dbae335eb883eb25b41e06a0723895f9e20f7bf/torch/nn/functional.py","note":"resize.cpp lines 925-934, 1065-1076, 3370-3381 at c8628d47; functional.py lines 5135-5138; same lines, 5->2 example"}]},"tags":[],"type":"article","links":[],"title":"Why does nearest-neighbour downscaling pick different source pixels in OpenCV, PyTorch, Pillow and skimage?","rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"summary":"OpenCV (c8628d47) INTER_NEAREST picks floor(x*scale) with no half-pixel offset, while INTER_NEAREST_EXACT picks floor((x+0.5)*scale) via a softdouble table its comment says matches Pillow; PyTorch documents mode='nearest' as matching OpenCV INTER_NEAREST and 'nearest-exact' as matching scikit-image and PIL. For 5->2 the two OpenCV modes select [0,2] vs [1,3] (hand calculation, not executed).","evidence":{"claims":[{"url":"https://github.com/opencv/opencv/blob/c8628d471ea5399eaf73db77cf0d46193fd44546/modules/imgproc/src/resize.cpp","claim":"OpenCV (c8628d47) INTER_NEAREST picks floor(x*scale) with no half-pixel offset, while INTER_NEAREST_EXACT picks floor((x+0.5)*scale) via a softdouble table its comment says matches Pillow; PyTorch documents mode='nearest' as matching OpenCV INTER_NEAREST and 'nearest-exact' as matching scikit-image and PIL. For 5->2 the two OpenCV modes select [0,2] vs [1,3] (hand calculation, not executed).","locator":"resize.cpp lines 925-934, 1065-1076, 3370-3381 at c8628d47; functional.py lines 5135-5138; same lines, 5->2 example","classification":"sourced_fact"}],"review":"unreviewed","execution":"not_run","inspection":"source_inspected","execution_record_ids":[]},"language":"en","categories":["T11","T12"],"extensions":{"curation/v1":{"curator":"CURATOR-A-20261021","revision":1,"topic_ids":["CAT:T11.03"],"confidence":"Low for code text.","limitations":["Static reading only; no resize, remap or distortion run. Index arithmetic below is curator hand calculation.","Source pin hashes are native catalogue descriptor hashes, not upstream byte hashes. 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