Parity audit: purecv ↔ OpenCV 4.10.0

Issues

• Parity audit: compare purecv with OpenCV 4.10.0, module by module

  documentationenhancement
  Feature

  webarkit/purecv#172 · Filter by author kalwalt opened on Oct 12, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

  

• core: add a shared saturate_cast (round-half-even + clamp)

  core-moduleenhancementrust-code
  webarkit/purecv#189 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• imgproc: round() ties away from zero where OpenCV rounds half to even

  bugimgproc-module
  webarkit/purecv#190 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• imgproc: cvt_color RGB→gray float path differs from OpenCV's fixed point

  bugimgproc-module
  webarkit/purecv#191 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• core: Matrix::convert_to truncates and errors instead of saturating

  bugcore-module
  webarkit/purecv#192 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• Orb: pyramid differs from OpenCV (level-size ties, INTER_LINEAR_EXACT resize, reflect-101 padding)

  enhancementfeatures2D-module
  webarkit/purecv#193 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• Orb: KeyPoint.size stays 7 instead of patch_size * level scale

  bugfeatures2D-module
  webarkit/purecv#194 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• Orb: compute() with caller-supplied keypoints lacks OpenCV's border filter and octave regrouping

  enhancementfeatures2D-module
  webarkit/purecv#195 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• Orb: per-level culling drops cutoff ties and re-sorts globally, unlike retainBest

  enhancementfeatures2D-module
  webarkit/purecv#196 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• Orb: per-level feature budget arithmetic differs from OpenCV (f64 vs f32 cvRound)

  enhancementfeatures2D-module
  webarkit/purecv#197 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• Orb: implement wta_k 3/4 descriptors and NormHamming2

  enhancementfeatures2D-modulewasm
  webarkit/purecv#198 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• Orb: implement patch_size != 31 (OpenCV RNG, random pattern, GET_VALUE sampling parity)

  enhancementfeatures2D-module
  webarkit/purecv#199 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• Orb: implement first_level > 0 (upscaled levels)

  enhancementfeatures2D-module
  webarkit/purecv#200 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• FastFeatureDetector: nonmax-off semantics differ from OpenCV (response value, threshold 0)

  enhancementfeatures2D-module
  webarkit/purecv#201 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• FastFeatureDetector: Type5_8 border and Type5_8/Type7_12 pre-test differ from OpenCV

  bugfeatures2D-module
  webarkit/purecv#202 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0
  1

• FastFeatureDetector: the simd feature has no effect on FAST

  enhancementfeatures2D-moduleSIMD
  webarkit/purecv#203 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• wasm: FAST/ORB threshold wraps modulo 256 instead of clamping to [0, 255]

  bugfeatures2D-modulewasm
  webarkit/purecv#204 · Filter by author kalwalt opened on Oct 17, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• core: add/subtract/multiply on integer types overflow instead of saturating (panic in debug, wrap in release, saturate only with simd)

  bugcore-moduleSIMD
  webarkit/purecv#208 · Filter by author kalwalt opened on Oct 19, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• core: divide differs from OpenCV 4.10.0: integer quotients truncate, float division by zero gives 0

  bugcore-module
  webarkit/purecv#209 · Filter by author kalwalt opened on Oct 19, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• core: *_scalar operands differ from OpenCV 4.10.0: scalar truncated, out-of-range scalar or result becomes 0

  bugcore-module
  webarkit/purecv#210 · Filter by author kalwalt opened on Oct 19, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• core: add_weighted differs from OpenCV 4.10.0: integer outputs truncate and out-of-range sums become 0

  bugcore-module
  webarkit/purecv#211 · Filter by author kalwalt opened on Oct 19, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• core: convert_scale_abs differs from OpenCV 4.10.0: ties round away from zero

  bugcore-module
  webarkit/purecv#212 · Filter by author kalwalt opened on Oct 19, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• core: check_range differs from OpenCV 4.10.0: upper bound is inclusive

  bugcore-module
  webarkit/purecv#213 · Filter by author kalwalt opened on Oct 19, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• core: norm differs from OpenCV 4.10.0: L2SQR, HAMMING, HAMMING2, RELATIVE and the two-array form are missing

  core-moduleenhancement
  webarkit/purecv#214 · Filter by author kalwalt opened on Oct 19, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0

• core: normalize differs from OpenCV 4.10.0: integer outputs truncate, dtype ignored, alpha/beta not sorted

  bugcore-module
  webarkit/purecv#215 · Filter by author kalwalt opened on Oct 19, 2026 · Parity audit: purecv ↔ OpenCV 4.10.0