帮助老丁去除编译器警告

charimg.h

@@ -267,9 +267,9 @@ inline void cimg_matrix(unsigned char grayimage[/*64*/][64])
 	{
 		const unsigned char * data = cimg_data + i *4;
 		unsigned char pixel[3] = {
-			(((data[0] - 33) << 2) | ((data[1] - 33) >> 4)),
-			((((data[1] - 33) & 0xF) << 4) | ((data[2] - 33) >> 2)),
-			((((data[2] - 33) & 0x3) << 6) | ((data[3] - 33)))
+			(unsigned char)(((data[0] - 33) << 2) | ((data[1] - 33) >> 4)),
+			(unsigned char)((((data[1] - 33) & 0xF) << 4) | ((data[2] - 33) >> 2)),
+			(unsigned char)((((data[2] - 33) & 0x3) << 6) | ((data[3] - 33)))
 		};
 		grayimage[i/64][i%64] = (unsigned int)(pixel[0]*0.299 + pixel[0]*0.587 + pixel[0]*0.114);
 	}

main.cpp

@@ -11,7 +11,7 @@ void demo_observe_vis();			//演示判断两个位置会不会被地表遮挡
 void demo_cover_grond_driven();		//演示由地表的位置发起计算，查阅场强, 绘制点阵图
 void demo_cover_slide_driven();		//演示由幻灯（或者天线）发起计算，获得地表的交点，绘制矢量图。
 
-int main(char /*argc*/, char * /*argv*/[])
+int main(int /*argc*/, char * /*argv*/[])
 {
 	demo_simple();
 	demo_perform();