imgproc: speed up getRectSubPix 8U->32F - #30050
### Summary
`getRectSubPix_8u32f`, the 8U-source -> 32F-patch path of `cv::getRectSubPix`, propagated the horizontal interpolation factor across the row:
```cpp
float prev = (1 - a)*(b1*src[0] + b2*src[src_step]);
for (int j = 0; j < win_size.width; j++) {
float t = a12*src[j+1] + a22*src[j+1+src_step];
dst[j] = prev + t;
prev = (float)(t*s); // loop-carried dependency
}
```
That recurrence is a serial dependency chain running the length of every row, so the loop neither pipelines nor vectorizes.
| patch size | 8U→32F | 32F→32F |
|---|---|---|
| 128×128 | 31.1 ms | 13.5 ms |
The recurrence is only a strength reduction. The bilinear weights are identical for every output pixel of a patch, so applying the constant 4-tap kernel directly gives the same result. This patch does that and vectorizes the loop with universal intrinsics (`vx_load_expand_q` → `v_cvt_f32` → 4× `v_mul`/`v_add` → `v_store`), keeping a scalar tail. `v_add`/`v_mul` are used instead of operators because the RVV scalable backend defines no operator overloads for its native vector types.
### Performance
SpacemiT K1 (RVV 1.0 / X60), `opencv_perf_imgproc --gtest_filter=*GetRectSubPix*`, `--perf_force_samples=20 --perf_min_samples=20`, `ALGO_HINT_ACCURATE`:
| patch | before | after | speedup |
|---|---|---|---|
| 16×16 | 0.610 ms | 0.308 ms | 1.98× |
| 32×32 | 2.116 ms | 0.843 ms | 2.51× |
| 64×64 | 8.016 ms | 2.822 ms | 2.84× |
| 128×128 | 31.109 ms | 10.369 ms | 3.00× |
The 8U→8U and 32F→32F paths are unchanged (0.99×–1.01×), and the whole `GetRectSubPix` perf suite improves from 81.66 ms to 53.95 ms (1.51×).
### Accuracy
`opencv_test_imgproc --gtest_filter=*GetRectSubPix*` passes on the same build.
```
Note: Google Test filter = *GetRectSubPix*
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from Imgproc_GetRectSubPix
[ RUN ] Imgproc_GetRectSubPix.accuracy
[ OK ] Imgproc_GetRectSubPix.accuracy (945 ms)
[----------] 1 test from Imgproc_GetRectSubPix (945 ms total)
[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (945 ms total)
[ PASSED ] 1 test.
```
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Fix function pointer signature mismatches - #30040
Contrib PR: https://github.com/opencv/opencv_contrib/pull/4224
Calling a function through a function pointer with a mismatched signature is undefined behavior in C/C++ and causes Clang Control Flow Integrity to trap with `SIGILL` (`ud1`) at indirect call sites.
This is a follow-up on https://github.com/opencv/opencv/pull/28939
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Remove deprecated CommaInitializer API - #29948
This goes hand in hand with https://github.com/opencv/opencv_contrib/pull/4217
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imgproc: fix NaN in phaseCorrelateIterative for float32 input - #29871
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### Summary
`cv::phaseCorrelateIterative` could return the image boundary as the detected shift (e.g. `(-32, -32)` for a 64x64 image) for ordinary float32 input, while the same input in float64 and the non-iterative `cv::phaseCorrelate` both return the correct shift. Reported in #29849 with a reproducer.
### Problem
`calculateCrossPowerSpectrum()` divided by the bin magnitude without a zero check. When a frequency bin of the cross power spectrum has exactly zero magnitude, the division produces NaN (0/0). A single NaN bin is enough: after the inverse DFT the whole correlation landscape becomes NaN, `minMaxLoc` degenerates, the peak lands on the wraparound corner, and the function exits through the out-of-bounds fallback returning `L3peak - L3mid = (-N/2, -M/2)`.
This is reachable with perfectly valid input: for a 64x64 image, bins where either frequency component hits Nyquist produce `dft1[bin] * conj(dft2[bin]) = 0` for Gaussian-like windows (the Hanning-windowed images issue #29849 used), because one of the DFT factors is exactly zero there.
### Solution
Two changes in `calculateCrossPowerSpectrum()`, both matching what the non-iterative implementation already does:
1. Guard the zero-magnitude case: a bin with zero magnitude has undefined phase, so write 0 instead of dividing by zero. `cv::divSpectrums()` handles the same situation by adding an epsilon to the denominator; zeroing the bin is equivalent here and keeps the output strictly on the unit circle.
2. Accumulate in `double` before rounding back to the storage type, as `cv::divSpectrums()` does in its CV_32F branch. This also protects large images, where float32 products of DFT bins can overflow to inf.
### Testing
- Reproduced #29849 with the issue's reproducer ported to C++: float32 returned `(-32, -32)` before the fix, `(-2.96, 1.99)` after (float64 reference: `(-2.94, 1.96)` for the true shift (-3, +2)).
- Added regression test `Imgproc_PhaseCorrelationIterative/64x64_float32_accuracy` covering this case. Verified it fails without the fix (returns `(-32, -32)`) and passes with it.
- `opencv_test_imgproc`: all 1635 tests pass with the fix (opencv_extra testdata, 5.x branch). The pre-existing `float32_overflow` and accuracy tests for the non-iterative path also pass.
imgproc: fix OpenCL matchTemplate TM_CCOEFF_NORMED precision loss - #29856
### Problem
`cv::matchTemplate(..., TM_CCOEFF_NORMED)` on `UMat` (OpenCL) input can return exactly `-1.0`/`1.0` for windows that are not actually near-perfect (anti-)matches, while the CPU path on the same data returns a sensible, correctly-bounded coefficient. See #21788: on the reporter's images, the CPU path gives `-0.8367...` where the OpenCL path gives exactly `-1.0` at a *different* location, so `minMaxLoc` picks the wrong match entirely.
### Root cause
The per-window denominator in `TM_CCOEFF_NORMED` is a variance-like quantity computed as a difference of two comparable-magnitude sums pulled from the image's integral images (`sum(x^2) - mean^2 * N`) -- classic catastrophic-cancellation territory. The CPU implementation (`common_matchTemplate` in `templmatch.cpp`) always accumulates these sums in `double` regardless of the input image's depth, so this is a non-issue there.
The OpenCL kernel (`matchTemplate_CCOEFF_NORMED` in `match_template.cl`), however, is fed integral images hard-coded to `CV_32F` (`integral(_image, image_sums, image_sqsums, CV_32F, CV_32F)`). On a realistic-sized image, the rounding error from that single-precision subtraction can dwarf a genuinely small-but-nonzero window variance. The corrupted (and effectively noise-dominated) ratio then spuriously trips the kernel's own `+-1` safety clamp (`normAcc()`, meant only for genuinely degenerate/near-constant windows) for windows that are not degenerate at all.
I initially assumed the fix was a missing epsilon guard (the CPU path has one: `diff2 <= min(0.5, 10*FLT_EPSILON*wndSum2) -> denominator = 0`, which the kernel lacks entirely). I verified this hypothesis against real integral-image data from an actual build and it's **false** -- adding the same epsilon guard to the float32 kernel path made *zero* difference (identical spurious-clamp count, tested on 480x640 and 1080x1920 synthetic images). The true variance in the failing windows isn't near-zero; it's just small relative to the accumulated sum magnitude, which is exactly what makes the cancellation error dominate without ever being "obviously degenerate" by the guard's own threshold. Precision is the only lever that actually fixes it.
### Fix
- Use `CV_64F` integral images (matching the CPU path exactly) when the OpenCL device supports double precision (`ocl::Device::getDefault().doubleFPConfig() > 0`), gated the same way the rest of the codebase gates double-precision OpenCL kernels (e.g. `sumpixels.dispatch.cpp`'s own `ocl_integral`, `thresh.cpp`). Verified against real integral-image data pulled from this build: residual error drops from up to `1.13` (!) to `~5e-5` (pure float32 output-storage rounding, since the result `Mat` stays `CV_32F` either way), and the spurious `+-1` clamp count drops from thousands to exactly zero, across multiple image sizes.
- On devices without double support, `matchTemplate_CCOEFF_NORMED` now returns `false` instead of silently running an already-known-inaccurate float32 kernel; `matchTemplate()`'s `CV_OCL_RUN` macro then falls through to the CPU path, which is always correct. This is a correctness-over-acceleration trade-off for this specific normalized method on such devices -- verified this fallback is exact (not just close): `cv::norm(cpuResult, gpuResult, NORM_INF) == 0.0` across three image sizes on such a device.
- Added the standard `cl_khr_fp64`/`cl_amd_fp64` extension-pragma block to `match_template.cl`, copied from the existing, already-shipping `integral_sum.cl` (same idiom used everywhere else in the codebase for this).
### Testing
- New regression test (`ccoeff_normed_large_low_contrast_image` in `modules/imgproc/test/ocl/test_match_template.cpp`) using a large (1920x1080), low-contrast synthetic image. The existing parameterized `OCL_ImageProc/MatchTemplate` test only covers small (<=100x100) images of uniformly random full-range noise, which never accumulates enough integral-sum magnitude to trigger this, so it doesn't catch the bug -- confirmed by temporarily reverting the fix and rerunning: the new test fails with `CPU minVal=-0.159..., GPU minVal=-1` (the exact reported symptom), and passes clean with the fix restored.
- Full existing `OCL_ImageProc/MatchTemplate.*` suite (96 tests, all methods/depths/channels/mask combinations) passes unchanged.
- Full existing `*MatchTemplate*` suite in `opencv_test_imgproc` (286 tests total including the new one) passes.
- Ran the full `opencv_test_imgproc` binary; the only failures (360, e.g. `StackBlur`, `HoughCircles`, `ColorBayer`) are pre-existing "can't find required data file" failures from a missing local `opencv_extra` checkout in my environment, unrelated to this change and confirmed to touch none of `templmatch.cpp`/`match_template.cl`.
Fixes#21788.
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- Skip downloading and embedding Unifont data when HAVE_HARFBUZZ is OFF
- Note: When HAVE_HARFBUZZ is OFF, Rubik and Unifont binaries will be excluded from the build.
When chtype is double (used by bicubic64fC1 .. bicubic64fC4),
std::is_same_v<double, float> evaluated to false.
As a result, buftype erroneously defaulted to int, and pixbuf was
allocated as int pixbuf[NCHANNELS][4].
That could trigger out of bound integer computations.
Extracted IPP to HAL for getRectSubPix function in 5.x - #29514
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Refactoring and moving IPP functions to HAL for bilateral_filter in Imgproc - #29409
**Performance Numbers on Intel(R) Core(TM) i9-11900K:** https://docs.google.com/spreadsheets/d/1hnH2aGmc3D88HGnvM34xczQbRZUgsKsAHorcB-DpLq4/edit?usp=sharing
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Imgproc test cleanup - #29740
co-authored by: @Prasadayus
### Re-enabled as-is (stale disable reasons)
- `FillPolyFully.fillpoly_fully` (`test_drawing.cpp:1142`)
- `Resize_Bitexact` (`test_resize_bitexact.cpp:188`, 4 instantiations): `INTER_NEAREST` and
`INTER_NEAREST_EXACT` agree exactly at integer upscale factors; measured 0.0 diff on all 4.
### Add assertions
- **imgproc** — new `Imgproc_Watershed.regression`: `cv::watershed` had no working coverage at all.
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imgproc: accept CV_Bool masks in matchTemplate (#25895) - #29677
### Problem
`cv::Mat_<bool>::depth()` returns `CV_Bool` in 5.0, where it returned `CV_8U` in 4.x. `matchTemplateMask` gates the mask at `templmatch.cpp:737`, so passing a boolean mask now fails with:
```
(-215:Assertion failed) _mask.depth() == CV_8U || _mask.depth() == CV_32F in function 'cv::matchTemplateMask'
```
A binary mask is a normal input for masked template matching, so this is a regression against 4.x.
### Fix
Allow `CV_Bool` in the assertion and widen the mask to `CV_8U` before the existing binarization step.
The widening is required rather than passing `CV_Bool` straight through, because `cv::threshold()` does not accept `CV_Bool`. Once widened, the existing `THRESH_BINARY` path treats any non-zero entry as selected, which is exactly the documented `CV_8U` mask semantics. `CV_8U` and `CV_32F` masks take an unchanged path.
The masked path is the only one affected: `cv::matchTemplate` routes every non-empty mask through `matchTemplateMask`, and there is no OpenCL mask variant.
### Test
`Imgproc_MatchTemplateBoolMask.matches_uchar_mask` compares a `Mat_<bool>` mask against the equivalent `CV_8UC1` mask and requires the results to agree, across all six match methods (`TM_SQDIFF`, `TM_SQDIFF_NORMED`, `TM_CCORR`, `TM_CCORR_NORMED`, `TM_CCOEFF`, `TM_CCOEFF_NORMED`) for `CV_8UC1`, `CV_8UC3` and `CV_32FC1` images. 18 parameter combinations.
Verified locally on 5.x: all 18 fail without the source change (with the assertion above) and pass with it. The full `*MatchTemplate*` set, 165 tests, passes. No test data needed, the test is synthetic.
Part of #25895, and follows the same approach as #29580, #29597 and #29622.
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cv::Mat_<bool>::depth() returns CV_Bool in 5.0 where it returned CV_8U in
4.x, so distanceTransform started rejecting boolean masks. CV_Bool is a
1-byte type whose values are only zero-tested here, so accept it wherever
a CV_8UC1 mask was previously accepted, matching the 4.x behaviour and the
4->5 migration guide.
Relaxes the type checks on all four reachable paths: the public wrapper,
distanceTransform_L1_8U, trueDistTrans (DIST_MASK_PRECISE) and
distanceATS_L1_8u (CV_8U output).
Closes#29596
The race is benign functionally because threads only modify
FOREGROUND (255) to VISITED_OUTER_RIGHT (100) or VISITED_ (200),
all of which are NON-ZERO. findStartContourPoint only cares if a
pixel is zero or non-zero, so its termination conditions are
unchanged. However, concurrent read/write of different values is
legally UB in C++ and triggers TSAN.
Refactoring and extracting IPP to HAL for threshold function in 5.x #29492
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Extracting IPP to HAL for matchTemplate function in 5.x #29466
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imgproc: extend boxFilter / gaussianBlurBinomial coverage in RISC-V RVV HAL #29440
### Summary
This PR extends RVV HAL coverage of the two most frequently used smoothing filters. Previously, `cv_hal_boxFilter` was only implemented for single-channel types (plus 32FC3) at 3×3/5×5, and `cv_hal_gaussianBlurBinomial` for 8UC1/16UC1/8UC4. The most common cases in practice — interleaved **8UC3** images and **7×7** box kernels — fell back to the core `FilterEngine` path, which runs single-threaded, costing 6–19× on multi-core RISC-V hardware.
New coverage:
- `boxFilter`: **8UC3 / 8UC4** (3×3, 5×5, 7×7); **7×7** for 8UC1, 16SC1, 32FC1, 32FC3 and the 8U→16U variant
- `gaussianBlurBinomial`: **8UC3** (3×3, 5×5)
Combinations already covered upstream keep their existing kernels byte-for-byte; net diff is +274/−162 across two files.
### Implementation
1. **Channel-blind "flat" kernels** (`boxFilterFlat8U<ksize, cn>`, `gaussianBlurFlat8U<ksize, cn>`). An interleaved row is processed as `width*cn` flat u8 elements whose horizontal taps sit at strides of `cn` elements: element *i* sums exactly its own channel's taps at `i, i+cn, …, i+(ksize−1)·cn`. One template therefore serves all channel counts, and:
- the horizontal pass becomes `ksize` independent unaligned `vle8` loads combined with widening adds — no `vlseg`/`vsseg` and no serial `vslide1down` chains, which are microcoded/serialized on current RVV hardware;
- the vertical pass is a single contiguous u16 stream processed at LMUL=8;
- the output is a plain `vse8` after saturating narrowing.
2. **Incremental vertical sliding window** for box with `ksize > 3`: the column-sum ring buffer keeps `ksize+1` rows so the window slides in O(1) per output row (add the entering row, subtract the leaving row) instead of re-summing `ksize` rows. u16 modular arithmetic stays exact because window sums never exceed 49·255 = 12495.
3. **Division-free normalization**: normalized box output uses multiply-high + shift (`m = ceil(2^18 / k²)`, Granlund–Montgomery; exact for divisors 9/25/49 over the full value range, verified per divisor) instead of long-latency vector integer division. Rounding is bit-identical to the previous `(sum + k²/2) / k²`.
4. **Existing kernels are extended, not rewritten**: `boxFilterC1` and the float `boxFilterC3` gain a 7×7 step in their existing unrolled style, so the 3×3/5×5 instantiations compile to the same code as before. The previous per-channel gaussian 8UC4 segment kernel is replaced by the flat kernel at measured parity, which is why the diff removes more gaussian lines than it adds.
5. Constraints respected: no hard-coded VLEN, RVV 1.0 intrinsics only, no scalable vector types in arrays.
### Performance
SpacemiT K1 (X60, rv64gcv, VLEN=256, 8×1.6 GHz), 1280×720, against a clean build of current 5.x HEAD.
**Measurement protocol:** each case is timed for **30 iterations** (after 2 warm-up runs) and the minimum is taken; the whole benchmark is executed in **2 interleaved rounds per library** (baseline/candidate alternated to cancel frequency/thermal drift, measured at up to 2× per run on this board), reporting the per-case minimum across rounds.
| Case | Generic | HAL | Speedup |
|------|--------:|----:|--------:|
| boxFilter 8UC1 7×7 | 6.539 ms | 0.330 ms | 19.8× |
| boxFilter 8UC3 3×3 | 7.325 ms | 0.994 ms | 7.4× |
| boxFilter 8UC3 5×5 | 8.118 ms | 1.142 ms | 7.1× |
| boxFilter 8UC3 7×7 | 15.930 ms | 1.328 ms | 12.0× |
| boxFilter 8UC4 3×3 | 9.552 ms | 1.466 ms | 6.5× |
| boxFilter 8UC4 5×5 | 10.775 ms | 1.841 ms | 5.9× |
| boxFilter 8UC4 7×7 | 14.268 ms | 2.112 ms | 6.8× |
| gaussianBlur 8UC3 3×3 | 2.382 ms | 1.023 ms | 2.3× |
| gaussianBlur 8UC3 5×5 | 2.746 ms | 1.684 ms | 1.6× |
**Geometric mean: ~6.1×** across the newly covered cases. Most of the box gain is the HAL's row-parallel execution (core `FilterEngine` has no internal parallelism) multiplied by the flat-layout kernels; the incremental window gives 7×7 a further ~1.9× over the plain flat version.
Regression check: the full `opencv_perf_imgproc` sweep (5610 timed cases, `--perf_min_samples=10`, one round per library) shows a geomean of 1.015× with no regressions beyond run-to-run noise — every case initially below 0.90× was re-verified with 2×2 interleaved rounds and per-case minima, and none persisted. The blur fixtures independently confirm 4.7–8.6× on 8UC4 across sizes and border types.
### Accuracy
- **Bit-exact against the core fallback**: for every newly covered combination (all 15 type/ksize pairs exercised), the HAL output was checksummed against the generic implementation on identical random inputs — all checksums match exactly. This includes the multiply-high normalization (bit-identical rounding to the previous division) and the incremental vertical window (u16 modular add/subtract cancels exactly).
- **Full accuracy suites**: `opencv_test_imgproc` filter/blur/smooth tests (`*BoxFilter*:*GaussianBlur*:*Blur*:*blur*:*Smooth*:*smooth*`) were run on K1 against a clean upstream HEAD build: **819 tests pass on both libraries, and the failure sets (pre-existing upstream failures, unrelated to this PR) are line-for-line identical**. These suites cover random anchors, all border modes, ROI offsets, and in-place operation.
- Combinations already covered upstream are unchanged by construction (same kernels, same codegen), so their accuracy behavior is inherited.
Note for reviewers: the large baseline gap also reflects that core `FilterEngine` runs single-threaded; that affects all non-HAL targets and may deserve a separate issue.
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Patch to opencv_extra has the same branch name.
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3rdparty(mlas): add missing power (ppc64le) kernel headers #29516
Closes: https://github.com/opencv/opencv/issues/29465
### Pull Request Readiness Checklist
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Distransform function IPP migration to HAL in 4.x #29463
### Pull Request Readiness Checklist
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Fix calibration tutorial docs, decomposeProjectionMatrix, and convertMaps performance claims #29487Fixes#25655, #26791, #27277.
Three doc fixes:
1. Calibration tutorial: rows/cols swapped, fixed np.mgrid consistency
2. decomposeProjectionMatrix: clarified transVect is camera center in homogeneous coordinates
3. convertMaps: replaced overstated 2x speed claim
### Pull Request Readiness Checklist
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Extracting IPP integaration as HAL for Canny #29434
Backport of : https://github.com/opencv/opencv/pull/29433
**Performance Numbers on Intel(R) Core(TM) i9-11900K:** https://docs.google.com/spreadsheets/d/1RMvUZP1tSQtdjuNQY9JasYmlx1L5iN9XWGhXtG5u1uI/edit?usp=sharing
### Pull Request Readiness Checklist
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Extracting IPP to HAL for matchTemplate function in 4.x #29464
### Pull Request Readiness Checklist
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Replace "static inline" by "inline" in headers #29453
This fixes#29436
I also replaced CV_INLINE which can be removed in a later PR.
I can make a similar PR for 4.x if you want.
### Pull Request Readiness Checklist
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Filter2D IPP extraction to HAL for 5.x #29428
### Pull Request Readiness Checklist
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Filter2D IPP migration to HAL for 4.x #29427
### Pull Request Readiness Checklist
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Merge pull request #29414 from Prasadayus:box_filter_refactor
Moving IPP functions to HAL for box_filter in Imgproc #29414
**Performance Numbers on Intel(R) Core(TM) i9-11900K:** https://docs.google.com/spreadsheets/d/1puWmOSTtAFwWjPu8J1SpuccPQvxUJU8NlFQs7mAZwL8/edit?usp=sharing
### Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
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Alexander Smorkalov
Ziyuan_Li
Vincent Rabaud
vrooomy
Abhishek Gola
Pranshul Soni
CodeCraftsman
Akansha Mallick
Kumataro
Prasad Ayush Kumar
Varun Jaiswal
Sean McBride
Neal Daftary
jeevan6996
Trishanth Mellimi
Teddy-Yangjiale
Alexander Smorkalov
FAN YUCHEN