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POTest NEON-optimized cv::threshold() on mobile device
 

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  1. POTest NEON-optimized cv::threshold() on mobile device
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    <p>I have been writing some optimizations for the OpenCV's threshold function, for ARM devices (mobile phones). It should be working on both Android and iPhone.</p> <p>However, I do not have a device to test it on, so I am looking for volunteers to give me a little help. If that motivates you more, I am planning to send it to OpenCV to be integrated into the main repository.</p> <p>I would be interested in code correctness, and if it happens to work as intended, some statistics for original/optimized performance. Do not forget to look at all scenarios.</p> <p>So, here is the code. To run it, paste in on <code>opencv/modules/imgproc/src/thresh.cpp</code>, at line 228 (as of 2.4.2) - just below SSE block, and recompile OpenCV. </p> <p>Also, add this line at the top of the file</p> <pre><code>#include &lt;arm_neon.h&gt; </code></pre> <p>Main code body:</p> <pre><code>#define CV_USE_NEON 1 #if CV_USE_NEON //if( checkHardwareSupport(CV_CPU_ARM_NEON) ) if( true ) { uint8x16_t thresh_u = vdupq_n_u8(thresh); uint8x16_t maxval_ = vdupq_n_u8(maxval); j_scalar = roi.width &amp; -8; for( i = 0; i &lt; roi.height; i++ ) { const uchar* src = (const uchar*)(_src.data + _src.step*i); uchar* dst = (uchar*)(_dst.data + _dst.step*i); switch( type ) { case THRESH_BINARY: for( j = 0; j &lt;= roi.width - 32; j += 32 ) { uint8x16_t v0, v1; v0 = vld1q_u8 ( src + j ); v1 = vld1q_u8 ( src + j + 16 ); v0 = vcgtq_u8 ( v0, thresh_u ); v1 = vcgtq_u8 ( v1, thresh_u ); v0 = vandq_u8 ( v0, maxval_ ); v1 = vandq_u8 ( v1, maxval_ ); vst1q_u8 ( dst + j, v0 ); vst1q_u8 ( dst + j + 16, v1 ); } for( ; j &lt;= roi.width - 8; j += 8 ) { uint8x8_t v2; v2 = vld1_u8( src + j ); v2 = vcgt_u8 ( v2, vget_low_s8 ( thresh_u ) ); v2 = vand_u8 ( v2, vget_low_s8 ( maxval_ ) ); vst1_u8 ( dst + j, v2 ); } break; case THRESH_BINARY_INV: for( j = 0; j &lt;= roi.width - 32; j += 32 ) { uint8x16_t v0, v1; v0 = vld1q_u8 ( src + j ); v1 = vld1q_u8 ( src + j + 16 ); v0 = vcleq_u8 ( v0, thresh_u ); v1 = vcleq_u8 ( v1, thresh_u ); v0 = vandq_u8 ( v0, maxval_ ); v1 = vandq_u8 ( v1, maxval_ ); vst1q_u8 ( dst + j, v0 ); vst1q_u8 ( dst + j + 16, v1 ); } for( ; j &lt;= roi.width - 8; j += 8 ) { uint8x8_t v2; v2 = vld1_u8( src + j ); v2 = vcle_u8 ( v2, vget_low_s8 ( thresh_u ) ); v2 = vand_u8 ( v2, vget_low_s8 ( maxval_ ) ); vst1_u8 ( dst + j, v2 ); } break; case THRESH_TRUNC: for( j = 0; j &lt;= roi.width - 32; j += 32 ) { uint8x16_t v0, v1; v0 = vld1q_u8 ( src + j ); v1 = vld1q_u8 ( src + j + 16 ); v0 = vminq_u8 ( v0, thresh_u ); v1 = vminq_u8 ( v1, thresh_u ); vst1q_u8 ( dst + j, v0 ); vst1q_u8 ( dst + j + 16, v1 ); } for( ; j &lt;= roi.width - 8; j += 8 ) { uint8x8_t v2; v2 = vld1_u8( src + j ); v2 = vmin_u8 ( v2, vget_low_s8 ( thresh_u ) ); vst1_u8 ( dst + j, v2 ); } break; case THRESH_TOZERO: for( j = 0; j &lt;= roi.width - 32; j += 32 ) { uint8x16_t v0, v1; v0 = vld1q_u8 ( src + j ); v1 = vld1q_u8 ( src + j + 16 ); v0 = vandq_u8 ( vcgtq_u8 ( v0, thresh_u ), vmaxq_u8 ( v0, thresh_u ) ); v1 = vandq_u8 ( vcgtq_u8 ( v1, thresh_u ), vmaxq_u8 ( v1, thresh_u ) ); vst1q_u8 ( dst + j, v0 ); vst1q_u8 ( dst + j + 16, v1 ); } for( ; j &lt;= roi.width - 8; j += 8 ) { uint8x8_t v2; v2 = vld1_u8 ( src + j ); v2 = vand_u8 ( vcgt_u8 ( v2, vget_low_s8(thresh_u) ), vmax_u8 ( v2, vget_low_s8(thresh_u) ) ); vst1_u8 ( dst + j, v2 ); } break; case THRESH_TOZERO_INV: for( j = 0; j &lt;= roi.width - 32; j += 32 ) { uint8x16_t v0, v1; v0 = vld1q_u8 ( src + j ); v1 = vld1q_u8 ( src + j + 16 ); v0 = vandq_u8 ( vcleq_u8 ( v0, thresh_u ), vminq_u8 ( v0, thresh_u ) ); v1 = vandq_u8 ( vcleq_u8 ( v1, thresh_u ), vminq_u8 ( v1, thresh_u ) ); vst1q_u8 ( dst + j, v0 ); vst1q_u8 ( dst + j + 16, v1 ); } for( ; j &lt;= roi.width - 8; j += 8 ) { uint8x8_t v2; v2 = vld1_u8 ( src + j ); v2 = vand_u8 ( vcle_u8 ( v2, vget_low_s8(thresh_u) ), vmin_u8 ( v2, vget_low_s8(thresh_u) ) ); vst1_u8 ( dst + j, v2 ); } break; } } } #endif </code></pre>
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    1. PTQuestion
    1. USCloudyMarble
    1. USSam
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      1. POTest NEON-optimized cv::threshold() on mobile device
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
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      1. POTest NEON-optimized cv::threshold() on mobile device
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    3. VO
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      1. USdom
      1. VTFavorite
    1. CO+1 - I would really love to if I had one of those devices. But I am unlucky.
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      1. POTest NEON-optimized cv::threshold() on mobile device
      1. USAbid Rahman K
    2. CO+1 - I'll give this a shot and will give you feedback soon!
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      1. POTest NEON-optimized cv::threshold() on mobile device
      1. USdom
    3. COGreat! If you are using Git, you can find here the complete patch pack to apply: http://answers.opencv.org/question/953/test-neon-optimized-cvthreshold-on-mobile-device/
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      1. POTest NEON-optimized cv::threshold() on mobile device
      1. USSam
 

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