实时处理Android相机帧 [英] Processing Android camera frames in real time

问题描述

我正在尝试创建一个实时处理相机帧的 Android 应用程序.首先，我只想显示相机看到的灰度版本.我已经设法从 onPreviewFrame 方法中的字节数组中提取适当的值.以下只是我的代码片段:

I'm trying to create an Android application that will process camera frames in real time. To start off with, I just want to display a grayscale version of what the camera sees. I've managed to extract the appropriate values from the byte array in the onPreviewFrame method. Below is just a snippet of my code:

byte[] pic;
int pic_size;
Bitmap picframe;
public void onPreviewFrame(byte[] frame, Camera c)
{
    pic_size = mCamera.getParameters().getPreviewSize().height * mCamera.getParameters().getPreviewSize().width;
    pic = new byte[pic_size];
    for(int i = 0; i < pic_size; i++)
    {
        pic[i] = frame[i];
    }
    picframe = BitmapFactory.decodeByteArray(pic, 0, pic_size);
}

byte[] 帧数组的第一个 [width*height] 值是亮度(灰度)值.提取它们后，如何将它们作为图像显示在屏幕上?它也不是二维数组，那么如何指定宽度和高度?

The first [width*height] values of the byte[] frame array are the luminance (greyscale) values. Once I've extracted them, how do I display them on the screen as an image? Its not a 2D array as well, so how would I specify the width and height?

推荐答案

您可以从 OpenCV4Android SDK.查看他们可用的示例，特别是 Tutorial 1 Basic.0 安卓相机

You can get extensive guidance from the OpenCV4Android SDK. Look into their available examples, specifically Tutorial 1 Basic. 0 Android Camera

但是，就我的情况而言，对于密集的图像处理，这将比实时图像处理应用程序所接受的要慢.一个很好的替代他们的 onPreviewFrame 的字节数组转换为 YUVImage:

But, as it was in my case, for intensive image processing, this will get slower than acceptable for a real-time image processing application. A good replacement for their onPreviewFrame 's byte array conversion to YUVImage:

YuvImage yuvImage = new YuvImage(frame, ImageFormat.NV21, width, height, null);

创建一个与图像大小相同的矩形.

Create a rectangle the same size as the image.

创建一个 ByteArrayOutputStream 并将其、矩形和压缩值传递给 compressToJpeg():

Create a ByteArrayOutputStream and pass this, the rectangle and the compression value to compressToJpeg():

ByteArrayOutputStream baos = new ByteArrayOutputStream();yuvimage.compressToJpeg(imageSizeRectangle, 100, baos);

byte [] imageData = baos.toByteArray();

位图预览Bitmap = BitmapFactory.decodeByteArray(imageData , 0, imageData .length);

在表面上渲染这些 previewFrames 和所涉及的最佳实践是一个新的维度.=)

Rendering these previewFrames on a surface and the best practices involved is a new dimension. =)

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