Optimization and correction of Delphi image skin replacement processing

I have seen an article about skin replacement for PNG images, but there are some problems in color processing, which are specially optimized and corrected. This is intended to reply to the problem of group friends, so BMP images are used, PNG images are processed in the same way. The Code is as follows:

Unit unit1;

Interface

Uses

Windows, messages, sysutils, variants, classes, graphics, controls, forms,

Dialogs, stdctrls, extctrls;

Type

Tform1 = Class (tform)

Colorbox1: tcolorbox;

Procedure btn1click (Sender: tobject );

Procedure colorbox1select (Sender: tobject );

Procedure formpaint (Sender: tobject );

Private

{Private Declarations}

Public

{Public declarations}

End;

VaR

Form1: tform1;

Implementation

{$ R *. DFM}

Procedure tform1.btn1click (Sender: tobject );

VaR

I, J: integer;

Row: prgbtriple;

RGB: longint;

Rgb_r, rgb_g, rgb_ B: byte;

Gray: byte;

BMP: tbitmap;

Begin

RGB: = colortorgb (colorbox1.selected );

Rgb_r: = getrvalue (RGB );

Rgb_g: = getgvalue (RGB );

Rgb_ B: = getbvalue (RGB );

BMP: = tbitmap. Create;

Try

BMP. loadfromfile ('e:/Documents and Settings/siow/desktop/main.bmp ');

For I: = 0 to BMP. Height-1 do

Begin

Row: = BMP. scanline [I];

For J: = 0 to BMP. Width-1 do

Begin

// Grayscale

Gray: = trunc (row ^. rgbtred * 306 + row ^. rgbtgreen * 601 + row ^. rgbtblue * 117 + 512) SHR 10 );

Row ^. rgbtred: = round (255-(255-gray) * (255-rgb_r)/255 );

Row ^. rgbtgreen: = round (255-(255-gray) * (255-rgb_g)/255 );

Row ^. rgbtblue: = round (255-(255-gray) * (255-rgb_ B)/255 );

INC (ROW );

End;

End;

Self. Canvas. stretchdraw (BMP. Canvas. cliprect, BMP );

Finally

BMP. Free;

End;

End;

Procedure tform1.colorbox1select (Sender: tobject );

Begin

Btn1click (NiL );

End;

Procedure tform1.formpaint (Sender: tobject );

Begin

Btn1click (NiL );

End;

End.