NV21是android平台摄像设备输出的标准格式,经常需要将它转为RGB或BGR格式, 以下是NV21格式图像矩阵转为RGB/BGR的实现代码,代码在windows/linux/android平台测试通过.
NV21格式的具体定义参见: 《YUV(NV21)图像数据到RGB颜色空间的转换》 关于YUV与RGB的转换网上有很多文章,参见:《YUV与RGB互转各种公式》
/**
* NV21图像转RGB或BGR
* @param input NV21格式图像数据
* @param width 图像宽度
* @param height 图像高度
* @param output 输出图像缓冲区
* @param isRGB 为{@code true}转为RGB图像,否则转为BGR图像
*/
public void NV212RGBorBGR(byte[]input , int width , int height , byte[]output,boolean isRGB)
{
int nvOff = width * height ;
int i, j, yIndex = 0;
int y, u, v;
int r, g, b, nvIndex = 0;
for(i = 0; i < height; i++){
for(j = 0; j < width; j ++,++yIndex){
nvIndex = (i / 2) * width + j - j % 2;
y = input[yIndex] & 0xff;
u = input[nvOff + nvIndex ] & 0xff;
v = input[nvOff + nvIndex + 1] & 0xff;
// yuv to rgb
r = y + ((351 * (v-128))>>8); //r
g = y - ((179 * (v-128) + 86 * (u-128))>>8); //g
b = y + ((443 * (u-128))>>8); //b
r = ((r>255) ?255 :(r<0)?0:r);
g = ((g>255) ?255 :(g<0)?0:g);
b = ((b>255) ?255 :(b<0)?0:b);
if(isRGB){
output[yIndex*3 + 0] = (byte) b;
output[yIndex*3 + 1] = (byte) g;
output[yIndex*3 + 2] = (byte) r;
}else{
output[yIndex*3 + 0] = (byte) r;
output[yIndex*3 + 1] = (byte) g;
output[yIndex*3 + 2] = (byte) b;
}
}
}
}
下面的C语言实现完全是从上面的java实现翻译过来的。
void NV212RGBorBGR(const uint8_t *input, int width, int height, uint8_t *output,bool isRGB)
{
int nv_off = width * height;
int i, j, y_index = 0;
int y, u, v;
int r, g, b, nv_index = 0;
for (i = 0; i < height; i++) {
for (j = 0; j < width; j++,++y_index) {
nv_index = i / 2 * width + j - j % 2;
y = input[y_index];
u = input[nv_off + nv_index];
v = input[nv_off + nv_index + 1];
r = y + ((351 * (v - 128)) >> 8); //r
g = y - ((179 * (v - 128) + 86 * (u - 128)) >> 8); //g
b = y + ((443 * (u - 128)) >> 8); //b
r = ((r>255) ? 255 : (r<0) ? 0 : r);
g = ((g>255) ? 255 : (g<0) ? 0 : g);
b = ((b>255) ? 255 : (b<0) ? 0 : b);
if (isRGB) {
output[y_index * 3 + 0] = (uint8_t)b;
output[y_index * 3 + 1] = (uint8_t)g;
output[y_index * 3 + 2] = (uint8_t)r;
}
else {
output[y_index * 3 + 0] = (uint8_t)r;
output[y_index * 3 + 1] = (uint8_t)g;
output[y_index * 3 + 2] = (uint8_t)b;
}
}
}
}
完整代码参见我的码云仓库 CsCvtUniImpl.java: https://gitee.com/l0km/jimgutil/blob/master/jimgutil/src/main/java/gu/jimgutil/CsCvtUniImpl.java gu_jimgutil_CsCvtNativeImpl.cpp: https://gitee.com/l0km/jimgutil/blob/master/native/src/gu_jimgutil_CsCvtNativeImpl.cpp