在android系统BitmapFactory空问题 [英] BitmapFactory null issue in android

问题描述

我想创建一个使用bitmapfactory位图类。我得到相机preVIEW图像YUV格式和去code手动灰度图像。当我尝试创建位图对象通过BitmapFactory返回null。

  {尝试
            对于（INT Y = 0; Y＆LT; frameHeight; Y ++）{
                为（中间体X = 0; X＆下; frameWidth; X ++）{                    字节灰色= YUVData [Y * frameWidth + X];
                    convertedData [Y *步幅+ 3 * X] =灰色;
                    convertedData [Y *步幅+ 3 * X + 1] =灰色;
                    convertedData [Y *步幅+ 3 * X + 2] =灰色;                }
            }            位图位=（位图）BitmapFactory.de codeByteArray的（convertedData，0，convertedData.length）;
 

解决方案

BitmapFactory用于创建，这是连接使用JPEG或PNG $ C $光盘映像文件的图像。如果你只是在它折腾的原始数据，功能不知道你用什么编码。 RGB？ YUV？ 24位？ 32位？

AFAIK有创建从YUV数据的图像没有原生的方式，你至少也得把它转换先RGB。这里是一个演示了一个答案：充分利用视频图像帧的Andr​​oid 。

当然，你可以使用NDK创建本机转换功能，这将是快了很多。或者你可以扫描一个YUV转换的文件，但我在一个快速扫描发现的唯一的事情是的 YuvImage ，这将只允许您将此转换为JPEG视频流。

I am trying to create bitmap class using bitmapfactory. I get camera preview image in YUV format and decode manually to grayscale image. When i try to create bitmap object via BitmapFactory it returns null.

        try {
            for (int y = 0; y < frameHeight; y++){
                for (int x = 0; x < frameWidth; x++){

                    byte grey = YUVData[y * frameWidth + x];
                    convertedData[y * stride + 3 * x] = grey;
                    convertedData[y * stride + 3 * x + 1] = grey;
                    convertedData[y * stride + 3 * x + 2] = grey;

                }
            }

            Bitmap bitmap =(Bitmap) BitmapFactory.decodeByteArray(convertedData, 0, convertedData.length);

解决方案

BitmapFactory is used to create an image from a image file that was encoded using JPEG or PNG. If you just toss raw data at it, the function has no idea what encoding you're using. RGB? YUV? 24-bit? 32-bit?

AFAIK there's no native way to create an image from YUV data, you'd at least have to convert it to RGB first. Here is an answer that demonstrates it: Getting frames from Video Image in Android.

Of course, you can use the NDK to create a native conversion function, which will be a lot faster. Or you could scan the documentation for a YUV converter, but the only thing I found in a quick scan is YuvImage, which will only allow you to convert this to a JPEG stream.

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