fun Bitmap.toGray(): Bitmap? { // 得到圖片的長和寬 // 創建目標灰度圖像 val bmpGray = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565) // 創建畫布 val c = Canvas(bmpGray) val paint = Paint() val cm = ColorMatrix() cm.setSaturation(0f) val f = ColorMatrixColorFilter(cm) paint.colorFilter = f c.drawBitmap(this, 0f, 0f, paint) return bmpGray }