- s = 1 / (ma - mi);
- o = mi / (ma - mi);
-
- // equations:
- // brightness + contrast * v
- // after autolevel:
- // brightness + contrast * (v * s - o)
- // =
- // (brightness - contrast * o) + (contrast * s) * v
- minimap.brightness = minimap.brightness - minimap.contrast * o;
- minimap.contrast *= s;
-
- Sys_Printf( "Auto level: Brightness changed to %f\n", minimap.brightness );
- Sys_Printf( "Auto level: Contrast changed to %f\n", minimap.contrast );
+ if(ma > mi)
+ {
+ s = 1 / (ma - mi);
+ o = mi / (ma - mi);
+
+ // equations:
+ // brightness + contrast * v
+ // after autolevel:
+ // brightness + contrast * (v * s - o)
+ // =
+ // (brightness - contrast * o) + (contrast * s) * v
+ minimap.brightness = minimap.brightness - minimap.contrast * o;
+ minimap.contrast *= s;
+
+ Sys_Printf( "Auto level: Brightness changed to %f\n", minimap.brightness );
+ Sys_Printf( "Auto level: Contrast changed to %f\n", minimap.contrast );
+ }
+ else
+ Sys_Printf( "Auto level: failed because all pixels are the same value\n" );