Question

我在Android中使用位图。当我转换为灰度时，我应该期望每个像素的值在0到255之间。但是对于像素，我将其中一些视为0而其他像素视为非常大的值。我不知道为什么。为什么我没有得到[0,255]范围内的值？我怎么得到它？

我的代码是：

//Converting to grayscale
                        int width, height;
                        height = mybitmap.getHeight();
                        width = mybitmap.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(mybitmap, 0, 0, paint);                
                        //Done bmpgrayscale is the grayscale image formed
                        Toast toast23=Toast.makeText(getApplicationContext(),"Grayscale made", Toast.LENGTH_LONG);  
                        toast23.show();
                        for (int i=0;i<210;i++){
                            for (int j=0;j<170;j++){

                                    Log.d("gray value is=", String.valueOf(bmpGrayscale.getPixel(i, j)));

                            }
                        }

输出的一部分是：

12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 0
12-07 23:14:28.022: D/gray value is=(958): 83886079
12-07 23:14:28.022: D/gray value is=(958): 317846001
12-07 23:14:28.022: D/gray value is=(958): 602992880
12-07 23:14:28.022: D/gray value is=(958): 669772779
12-07 23:14:28.022: D/gray value is=(958): 904719596
12-07 23:14:28.022: D/gray value is=(958): 971894253
12-07 23:14:28.022: D/gray value is=(958): 1223552493
12-07 23:14:28.022: D/gray value is=(958): 1223552493
12-07 23:14:28.022: D/gray value is=(958): 1223552493
12-07 23:14:28.022: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493
12-07 23:14:28.052: D/gray value is=(958): 1223552493

请帮忙。我使用它将我的视图转换为位图，然后将位图转换为灰度。

修改

//Converting to grayscale
                        int width, height;
                        height = mybitmap.getHeight();
                        width = mybitmap.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(mybitmap, 0, 0, paint);                
                        //Done bmpgrayscale is the grayscale image formed
                        Toast toast23=Toast.makeText(getApplicationContext(),"Grayscale made", Toast.LENGTH_LONG);  
                        toast23.show();
                        for (int i=0;i<210;i++){
                            for (int j=0;j<170;j++){
                                    int a=bmpGrayscale.getPixel(i, j);
                                    ByteBuffer b = ByteBuffer.allocate(4);
                                  //b.order(ByteOrder.BIG_ENDIAN); // optional, the initial order of a byte buffer is always BIG_ENDIAN.
                                    b.putInt(a  );

                                    byte[] result = b.array();                                      
                                    Log.d("gray value is=", String.valueOf((int)result[0]));

                            }
                        }

Answer 1

不确定为什么你会得到负值，可能是溢出的东西？这就是我做的事情

int value = getLastBytes(1223552493); //Prints 237, the dec value of ED 

public int getLastBytes(long original) {
String hexBytes = Long.toHexString(original);
return Integer.parseInt(hexBytes.substring(hexBytes.length()-2),16);
}

在你的情况下，你可能会这样称呼它：

Log.d("gray value is=", getLastBytes(bmpGrayscale.getPixel(i, j)));

位图 - 获得非常大的值

1 个答案: