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java - 字节数组进入灰度。安卓拍照

问题描述

当我在 android 中制作照片时，我从相机收到一个字节数组。我想将此数组（图像）转换为 2 种颜色 - 白色和黑色。有任何想法吗？将相机模式更改为单声道/负片对我来说不是一个解决方案。

问候。

EDIT1：代码是Java

标签： javaandroidcolorscameraimage-thresholding

解决方案

首先，您需要从数组创建位图：

BitmapFactory.Options options = new BitmapFactory.Options();
options.inMutable = true;
// data is your byte array
Bitmap bmpOriginal = BitmapFactory.decodeByteArray(data, 0, data.length, options); 
Canvas canvas = new Canvas(bmpOriginal);
Bitmap bmpGrayscale = toGrayscale(bmpOriginal);
bmpOriginal.recycle(); // free memory immediately, as your bitmap is not garbage collected by now.

然后，您可以将bmpOriginal彩色图像传递给转换方法

public Bitmap toGrayscale(Bitmap bmpOriginal) {        
    int width, height;
    height = bmpOriginal.getHeight();
    width = bmpOriginal.getWidth();    

    Bitmap bmpGrayscale = Bitmap.createBitmap(width, height,    Bitmap.Config.ARGB_8888);
    Canvas c = new Canvas(bmpGrayscale);
    Paint paint = new Paint();
    ColorMatrix cm = new ColorMatrix();
    cm.setSaturation(0);
    ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
    paint.setColorFilter(f);
    c.drawBitmap(bmpOriginal, 0, 0, paint);
    return bmpGrayscale;
}

上面的代码会给你灰度位图。它只是将零饱和度过滤器应用于图像。由于饱和度是颜色的纯度，纯度越低 - 色差越小。应用上述过滤器后，您得到的唯一区别是亮度。最亮的是白色，最暗的是黑色。如果要将其转换回字节数组，可以尝试以下操作：

Bitmap bmpGrayscale = intent.getExtras().get("data");
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmpGrayscale.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
bmpGrayscale.recycle(); // free memory immediately, as your bitmap is not garbage collected by now.

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