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    <p>It should be fairly straightforward to write this function using vector intrinsics. I don't know what processor, compiler, or packed pixel format you're using, so I'll give an example implementation using GCC and MMX intrinsics for x86. It should also be easy to translate this code into ARM NEON, PowerPC Altivec, or x86/x64 SSE code.</p> <p>This should convert RGB planar to 32-bit RGBA packed, although ARGB is actually more common. If you need 24-bit RGB you're going to have to get a bit creative. The "Software Developer Manual" for your processor will be your best friend when writing this small piece of code, and you'll also need to read the documentation for your compiler.</p> <p>SIMD handles this very well, you can tell by how short the code is below. Note that the code below is actually C99, not C++, as C99 gives access to the <code>restrict</code> keyword which can reduce the number of loads and stores generated.</p> <p>Also note that this code has strict alignment requirements.</p> <pre><code>#include &lt;stddef.h&gt; #if defined(USE_MMX) typedef char v8qi __attribute__ ((vector_size(8))); void pack_planes3(void *dest, const void *src[3], size_t n) { v8qi *restrict dp = dest, x, y, zero = { 0, 0, 0, 0, 0, 0, 0, 0 }; const v8qi *restrict sp1 = src[0]; const v8qi *restrict sp2 = src[1]; const v8qi *restrict sp3 = src[2]; size_t i; for (i = 0; i &lt; n; i += 8) { x = __builtin_ia32_punpckhbw(*sp1, *sp3); y = __builtin_ia32_punpckhbw(*sp2, zero); dp[0] = __builtin_ia32_punpckhbw(x, y); dp[1] = __builtin_ia32_punpcklbw(x, y); x = __builtin_ia32_punpcklbw(*sp1, *sp3); y = __builtin_ia32_punpcklbw(*sp2, zero); dp[2] = __builtin_ia32_punpckhbw(x, y); dp[3] = __builtin_ia32_punpcklbw(x, y); sp1++; sp2++; sp3++; dp += 4; } } #else /* Scalar implementation goes here */ #endif </code></pre>
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    1. POIs there a good library or algorithm that help convert planar image to interleaved image fast(C++)?
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    1. USDietrich Epp
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    1. COThx. I am not too familiar with GCC and I don't have experience with MMX either. The compiler I have is MSVC and the processor is intel. I sort of understand the code does here. What should I need to do if I want to try it on my platform?
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    2. CO@Scrathis: Refer to the x86 manuals (http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html/) for information about what the instructions do, and refer to the MSVC documentation (http://msdn.microsoft.com/en-us/library/y0dh78ez(v=vs.80).aspx) for information about how to access the instructions from your compiler.
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