NV21转RGB或BGR的java实现和C实现

亦凉 2023-07-12 06:20 3阅读 0赞

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》][YUV_NV21_RGB]  
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》][YUV_RGB]

# java实现 #

/**
    	 * 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;
    	            }
    	        }
    	    }
    	}

# C 实现 #

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][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][https_gitee.com_l0km_jimgutil_blob_master_native_src_gu_jimgutil_CsCvtNativeImpl.cpp]

[YUV_NV21_RGB]: https://blog.csdn.net/u011178262/article/details/84201597
[YUV_RGB]: https://blog.csdn.net/xiaoyafang123/article/details/82153279
[https_gitee.com_l0km_jimgutil_blob_master_jimgutil_src_main_java_gu_jimgutil_CsCvtUniImpl.java]: https://gitee.com/l0km/jimgutil/blob/master/jimgutil/src/main/java/gu/jimgutil/CsCvtUniImpl.java
[https_gitee.com_l0km_jimgutil_blob_master_native_src_gu_jimgutil_CsCvtNativeImpl.cpp]: https://gitee.com/l0km/jimgutil/blob/master/native/src/gu_jimgutil_CsCvtNativeImpl.cpp