Huge negative values extracted by using getPixel() method

问题:

I am having a problem with an image processing app I am developing (newbie here). I am trying to extract the value of specific pixels by using the getPixel() method.

I am having a problem though. The number I get from this method is a huge negative number, something like -1298383. Is this normal? How can I fix it?

Thanks.

回答1:

I'm not an expert, but to me it looks like you are getting the hexadecimal value. Perhaps you want something more understandable like the value of each RGB layer.

To unpack a pixel into its RGB values you should do something like:

private short[][] red; private short[][] green; private short[][] blue;   /**   * Map each intensity of an RGB colour into its respective colour channel  */ private void unpackPixel(int pixel, int row, int col) {     red[row][col] = (short) ((pixel >> 16) & 0xFF);     green[row][col] = (short) ((pixel >> 8) & 0xFF);     blue[row][col] = (short) ((pixel >> 0) & 0xFF); } 

And after changes in each channel you can pack the pixel back.

/**   * Create an RGB colour pixel.  */ private int packPixel(int red, int green, int blue) {     return (red << 16) | (green << 8) | blue; } 

Sorry if it is not what you are looking for.

回答2:

You can get the pixel from the view like this:

ImageView imageView = ((ImageView)v); Bitmap bitmap = ((BitmapDrawable)imageView.getDrawable()).getBitmap(); int pixel = bitmap.getPixel(x,y); 

Now you can get each channel with:

int redValue = Color.red(pixel); int blueValue = Color.blue(pixel); int greenValue = Color.green(pixel); 

回答3:

getPixel() returns the Color at the specified location. Throws an exception if x or y are out of bounds (negative or >= to the width or height respectively).

The returned color is a non-premultiplied ARGB value.

文章来源: Huge negative values extracted by using getPixel() method