threshold() [2/2]

MAYAFLUX_API void MayaFlux::Kinesis::Vision::threshold	(	std::span< const float >	gray,
		std::span< float >	dst,
		float	value
	)

Global threshold writing into caller-supplied buffer.

Parameters

gray	Input span, size must be w * h.
dst	Output span, size must be w * h.
value	Threshold value in [0, 1].

Definition at line 194 of file PixelOps.cpp.

{
    const size_t n = gray.size();
    const float* src = gray.data();
    float* out = dst.data();
 
#ifdef MAYAFLUX_ARCH_X64
    const __m256 thresh = _mm256_set1_ps(value);
    const __m256 one = _mm256_set1_ps(1.0F);
    size_t i = 0;
    for (; i + 8 <= n; i += 8) {
        __m256 v = _mm256_loadu_ps(src + i);
        __m256 mask = _mm256_cmp_ps(v, thresh, _CMP_GE_OS);
        _mm256_storeu_ps(out + i, _mm256_and_ps(mask, one));
    }
    for (; i < n; ++i)
        out[i] = src[i] >= value ? 1.0F : 0.0F;
 
#elif defined(MAYAFLUX_ARCH_ARM64)
    const float32x4_t thresh = vdupq_n_f32(value);
    const float32x4_t one = vdupq_n_f32(1.0F);
    size_t i = 0;
    for (; i + 4 <= n; i += 4) {
        float32x4_t v = vld1q_f32(src + i);
        uint32x4_t mask = vcgeq_f32(v, thresh);
        vst1q_f32(out + i,
            vreinterpretq_f32_u32(vandq_u32(mask, vreinterpretq_u32_f32(one))));
    }
    for (; i < n; ++i)
        out[i] = src[i] >= value ? 1.0F : 0.0F;
 
#else
    std::transform(std::execution::par_unseq, gray.begin(), gray.end(), dst.begin(),
        [value](float v) { return v >= value ? 1.0F : 0.0F; });
#endif
}

References dst, out, src, and value.