提取Android摄像头的NV21格式的黑白图像 [英] Extract black and white image from android camera's NV21 format

问题描述

我已经做了一些谷歌，荷兰国际集团周围，但没有找到有关这种格式足够的信息。这是摄像头preVIEW的默认格式。任何人都可以提出的关于它的信息以及如何提取数据的良好来源，从与该格式的照片/ preVIEW形象？更具体地，我需要的黑白图像中提取

I have done some google-ing around and couldn't find enough information about this format. It is the default format for camera preview. Can anyone suggest good sources of information about it and how to extract data from a photo/preview image with that format? To be more specific, I need the black and white image extracted.

编辑：好像该格式也被称为420的YCbCr半平面

Seems like that format is also called YCbCr 420 Semi Planar

推荐答案

我制定了以下code转换的NV21为RGB，并且工作。

I developed the following code to convert the NV21 to RGB, and it is working.

/**
 * Converts YUV420 NV21 to RGB8888
 * 
 * @param data byte array on YUV420 NV21 format.
 * @param width pixels width
 * @param height pixels height
 * @return a RGB8888 pixels int array. Where each int is a pixels ARGB. 
 */
public static int[] convertYUV420_NV21toRGB8888(byte [] data, int width, int height) {
    int size = width*height;
    int offset = size;
    int[] pixels = new int[size];
    int u, v, y1, y2, y3, y4;

    // i percorre os Y and the final pixels
    // k percorre os pixles U e V
    for(int i=0, k=0; i < size; i+=2, k+=2) {
        y1 = data[i  ]&0xff;
        y2 = data[i+1]&0xff;
        y3 = data[width+i  ]&0xff;
        y4 = data[width+i+1]&0xff;

        u = data[offset+k  ]&0xff;
        v = data[offset+k+1]&0xff;
        u = u-128;
        v = v-128;

        pixels[i  ] = convertYUVtoRGB(y1, u, v);
        pixels[i+1] = convertYUVtoRGB(y2, u, v);
        pixels[width+i  ] = convertYUVtoRGB(y3, u, v);
        pixels[width+i+1] = convertYUVtoRGB(y4, u, v);

        if (i!=0 && (i+2)%width==0)
            i+=width;
    }

    return pixels;
}

private static int convertYUVtoRGB(int y, int u, int v) {
    int r,g,b;

    r = y + (int)1.402f*v;
    g = y - (int)(0.344f*u +0.714f*v);
    b = y + (int)1.772f*u;
    r = r>255? 255 : r<0 ? 0 : r;
    g = g>255? 255 : g<0 ? 0 : g;
    b = b>255? 255 : b<0 ? 0 : b;
    return 0xff000000 | (b<<16) | (g<<8) | r;
}

这形象有助于理解。

This image helps to understand.

如果你想仅仅灰度图是easer。您可以放弃所有的U和V的信息，并采取只在Y信息。在code也可以是这样的：

If you wanna just grayscale image is easer. You can discard all the U and V info, and take just the Y info. The code would can be like this:

/**
 * Converts YUV420 NV21 to Y888 (RGB8888). The grayscale image still holds 3 bytes on the pixel.
 * 
 * @param pixels output array with the converted array o grayscale pixels
 * @param data byte array on YUV420 NV21 format.
 * @param width pixels width
 * @param height pixels height
 */
public static void applyGrayScale(int [] pixels, byte [] data, int width, int height) {
    int p;
    int size = width*height;
    for(int i = 0; i < size; i++) {
        p = data[i] & 0xFF;
        pixels[i] = 0xff000000 | p<<16 | p<<8 | p;
    }
}

要创建位图只是：

Bitmap bm = Bitmap.createBitmap(pixels, width, height, Bitmap.Config.ARGB_8888);

在哪里像素是你的INT []数组。

Where pixels is your int [] array.

这篇关于提取Android摄像头的NV21格式的黑白图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！