Xorg: yuv rfx unsigned

xorg/server/module/rdpCapture.c

@@ -177,13 +177,14 @@ rdpCopyBox_a8r8g8b8_to_yuvalp(int ax, int ay,
                 y = (r *  19595 + g *  38470 + b *   7471) >> 16;
                 u = (r * -11071 + g * -21736 + b *  32807) >> 16;
                 v = (r *  32756 + g * -27429 + b *  -5327) >> 16;
-                y = y - 128;
-                y = max(y, -128);
-                u = max(u, -128);
-                v = max(v, -128);
-                y = min(y, 127);
-                u = min(u, 127);
-                v = min(v, 127);
+                u = u + 128;
+                v = v + 128;
+                y = max(y, 0);
+                u = max(u, 0);
+                v = max(v, 0);
+                y = min(y, 255);
+                u = min(u, 255);
+                v = min(v, 255);
                 *(yptr++) = y;
                 *(uptr++) = u;
                 *(vptr++) = v;