Image processing algorithm (3)

Iii. brightness
This function is used to increase the brightness of the image. It has an addition parameter-nbrightness, Which is input by the user and ranges from-255 ~ 255. After obtaining the brightening parameter, the function's unsafe Code Processing the different color components of each pixel point one by one, that is, adding an brightening parameter to the original value to obtain the new value. At the same time, there is an operation in the code to prevent the score from crossing the border, because the RGB score range is 0 ~ 255. You need to reset the value once the value exceeds this range. After the function is successfully executed, true must be returned. 1 Public   Static   Bool Brightness (Bitmap B, Int Nbrightness)
2 {
3 If (Nbrightness <   - 255   | Nbrightness >   255 )
4 Return   False ;
5 Bitmapdata bmdata = B. lockbits ( New Rectangle ( 0 , 0 , B. Width,
6 B. Height), imagelockmode. readwrite,
7 Pixelformat. format24bpprgb );
8 Int Stride = Bmdata. stride;
9 System. intptr scan0 = Bmdata. scan0;
10 Int Nval =   0 ;
11 Unsafe
12 {
13 Byte   * P = ( Byte   * )( Void   * ) Scan0;
14 Int Noffset = Stride - B. Width * 3 ;
15 Int Nwidth = B. Width *   3 ;
16 For ( Int Y = 0 ; Y < B. height; ++ Y)
17 {
18 For ( Int X = 0 ; X < Nwidth; ++ X)
19 {
20 Nval = ( Int ) (P [ 0 ] + Nbrightness );
21 If (Nval <   0 ) Nval =   0 ;
22 If (Nval >   255 ) Nval =   255 ;
23 P [ 0 ] = ( Byte ) Nval;
24 ++ P;
25 }
26 P + = Noffset;
27 }
28 }
29 B. unlockbits (bmdata );
30 Return   True ;
31 }