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// These utility functions allow for the conversion of RGB data to YUV data.
#include "tensorflow/examples/android/jni/rgb2yuv.h"
#include "tensorflow/core/platform/port.h"
using namespace tensorflow;
static inline void WriteYUV(const int x, const int y, const int width,
const int r8, const int g8, const int b8,
uint8* const pY,
uint8* const pUV) {
// Using formulas from http://msdn.microsoft.com/en-us/library/ms893078
*pY = ((66 * r8 + 129 * g8 + 25 * b8 + 128) >> 8) + 16;
// Odd widths get rounded up so that UV blocks on the side don't get cut off.
const int blocks_per_row = (width + 1) / 2;
// 2 bytes per UV block
const int offset = 2 * (((y / 2) * blocks_per_row + (x / 2)));
// U and V are the average values of all 4 pixels in the block.
if (!(x & 1) && !(y & 1)) {
// Explicitly clear the block if this is the first pixel in it.
pUV[offset] = 0;
pUV[offset + 1] = 0;
}
// V (with divide by 4 factored in)
#ifdef __APPLE__
const int u_offset = 0;
const int v_offset = 1;
#else
const int u_offset = 1;
const int v_offset = 0;
#endif
pUV[offset + v_offset] += ((112 * r8 - 94 * g8 - 18 * b8 + 128) >> 10) + 32;
// U (with divide by 4 factored in)
pUV[offset + u_offset] += ((-38 * r8 - 74 * g8 + 112 * b8 + 128) >> 10) + 32;
}
void ConvertARGB8888ToYUV420SP(const uint32* const input, uint8* const output,
int width, int height) {
uint8* pY = output;
uint8* pUV = output + (width * height);
const uint32* in = input;
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
const uint32 rgb = *in++;
#ifdef __APPLE__
const int nB = (rgb >> 8) & 0xFF;
const int nG = (rgb >> 16) & 0xFF;
const int nR = (rgb >> 24) & 0xFF;
#else
const int nR = (rgb >> 16) & 0xFF;
const int nG = (rgb >> 8) & 0xFF;
const int nB = rgb & 0xFF;
#endif
WriteYUV(x, y, width, nR, nG, nB, pY++, pUV);
}
}
}
void ConvertRGB565ToYUV420SP(const uint16* const input, uint8* const output,
const int width, const int height) {
uint8* pY = output;
uint8* pUV = output + (width * height);
const uint16* in = input;
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
const uint32 rgb = *in++;
const int r5 = ((rgb >> 11) & 0x1F);
const int g6 = ((rgb >> 5) & 0x3F);
const int b5 = (rgb & 0x1F);
// Shift left, then fill in the empty low bits with a copy of the high
// bits so we can stretch across the entire 0 - 255 range.
const int r8 = r5 << 3 | r5 >> 2;
const int g8 = g6 << 2 | g6 >> 4;
const int b8 = b5 << 3 | b5 >> 2;
WriteYUV(x, y, width, r8, g8, b8, pY++, pUV);
}
}
}
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