c# - Detect bright and dark images -

i have code stackoverflow answers detect bright , dark images

the problem not work , don't know why.

for example if call

isdark(bitmap, 40, 0.9); // sees image bright 

any value 0.1 0.99 returns bright image , other value above 0.99 returns images dark.

the tolerance value seems have no effect if set 1 250.

 // fast access pixels             public static unsafe byte[] bitmaptobytearray(bitmap bitmap)     {         bitmapdata bmd = bitmap.lockbits(new rectangle(0, 0, bitmap.width, bitmap.height), imagelockmode.readonly,                                          pixelformat.format32bppargb);         byte[] bytes = new byte[bmd.height * bmd.stride];         byte* pnt = (byte*)bmd.scan0;         marshal.copy((intptr)pnt, bytes, 0, bmd.height * bmd.stride);         bitmap.unlockbits(bmd);         return bytes;     }      public bool isdark(bitmap bitmap, byte tolerance, double darkprocent)     {         byte[] bytes = bitmaptobytearray(bitmap);         int count = 0, = bitmap.width * bitmap.height;         (int = 0; < bytes.length; += 4)         {             byte r = bytes[i + 2], g = bytes[i + 1], b = bytes[i];             byte brightness = (byte)math.round((0.299 * r + 0.5876 * g + 0.114 * b));             if (brightness <= tolerance)                 count++;         }         return (1d * count / all) <= darkprocent;     } 

ok, after looking @ again, notice comparison @ end of function looks backwards (based on name of variable "darkprocent"). think comparison operator should >=, not <=.

that got me answers expecting test images.