如何修改一张图片的颜色通道

Question

以前记得有个delphi程序的例子是修改图片颜色通道的.
一时想不起来了.请高手指教一下.
如何修改一张图片的RGB,最好R,G,B,能分开说一下.或发原代码学习一下

Answer 1

给lz一些代码看看，希望能有所帮助：
// 计算BITMAP的平均亮度
function getbmpbrightness(thebitmap: tbitmap): byte; 
var
  i,j: integer;
  p: pbytearray;
  hh,ww: integer;
  sum: int64;
  total: int64;
begin
  sum:=0;
  total:=0;
  with thebitmap do
  begin
    hh:=thebitmap.height;
    ww:=thebitmap.width;
    i:=0;
    while i<hh do
    begin
      p:=scanline[i];
      inc(i,3);
      for j:=0 to ww-1 do
      begin
        sum:=sum+p[j*3]+p[j*3+1]+p[j*3+2];// &&&
        total:=total+3;// &&&
      end;
    end;
  end;
  result:=sum div total;
end;
以上为计算BITMAP的平均亮度的函数。
在计算中没有考虑RGB三种颜色的加权。
如果只计算某种颜色通道的平均亮度，
则将total:=total+3改为+1，
将sum:=sum+p[j*3]+p[j*3+1]+p[j*3+2]
改为sum:=sum+p[j*3]或p[j*3+1]或p[j*3+2]
返回值为0-255之间的一个数值。
要求thebitmap为24bit。
// bitmap的平滑（模糊），其中，smoothlevel为平滑程度，取值为1、2、3
// x1,y1,x2,y2为此BITMAP中需要平滑的范围。
// 要求mybitmap为24bit。
procedure bmpSmooth(mybitmap: tbitmap; smoothlevel: byte; x1,y1,x2,y2: integer);
var
  p,p1,p2: pbytearray;
  i,j: integer;
  thew,theh: integer;
  s1,s2,s3: integer;
  rvalue: integer;
  gvalue: integer;
  bvalue: integer;
  tmpbitmap: tbitmap;
  maxnum,minnum: integer;
begin
  tmpbitmap:=tbitmap.create;
  tmpbitmap.assign(mybitmap);
  with mybitmap do
  begin
    thew:=width;
    theh:=height;
    if (x1=x2) or (y1=y2) then
    begin
      x1:=2;
      y1:=2;
      x2:=thew-2;
      y2:=theh-2;
    end
    else
    begin
      minnum:=min(y1,y2);
      maxnum:=max(y1,y2);
      y1:=minnum;
      y2:=maxnum;
      minnum:=min(x1,x2);
      maxnum:=max(x1,x2);
      x1:=minnum;
      x2:=maxnum;
    end;
    if x1<2 then x1:=2;
    if y1<2 then y1:=2;
    if x2>thew-2 then x2:=thew-2;
    if y2>theh-2 then y2:=theh-2;
    for i:=y1 to y2 do
    begin
      p:=ScanLine[i];
      p1:=tmpbitmap.scanline[i-1];
      p2:=tmpbitmap.scanline[i+1];
      for j:=x1 to x2 do
      begin
        s1:=j*3;
        s2:=j*3+1;
        s3:=j*3+2;
        case smoothlevel of
          1: begin  // 轻微
               rvalue:=(p[s3]*3+p[s3-3]+p[s3+3]+p1[s3]+p1[s3-3]+p1[s3+3]+
                        p2[s3]+p2[s3-3]+p2[s3+3]) div 11;
               gvalue:=(p[s2]*3+p[s2-3]+p[s2+3]+p1[s2]+p1[s2-3]+p1[s2+3]+
                        p2[s2]+p2[s2-3]+p2[s2+3]) div 11;
               bvalue:=(p[s1]*3+p[s1-3]+p[s1+3]+p1[s1]+p1[s1-3]+p1[s1+3]+
                        p2[s1]+p2[s1-3]+p2[s1+3]) div 11;
             end;
          2: begin  // 普通
               rvalue:=(p[s3]*2+p[s3-3]+p[s3+3]+p1[s3]+p1[s3-3]+p1[s3+3]+
                        p2[s3]+p2[s3-3]+p2[s3+3]) div 10;
               gvalue:=(p[s2]*2+p[s2-3]+p[s2+3]+p1[s2]+p1[s2-3]+p1[s2+3]+
                        p2[s2]+p2[s2-3]+p2[s2+3]) div 10;
               bvalue:=(p[s1]*2+p[s1-3]+p[s1+3]+p1[s1]+p1[s1-3]+p1[s1+3]+
                        p2[s1]+p2[s1-3]+p2[s1+3]) div 10;
             end;
          3: begin  // 加强
               rvalue:=(p[s3]+p[s3-3]+p[s3+3]+p1[s3]+p1[s3-3]+p1[s3+3]+
                        p2[s3]+p2[s3-3]+p2[s3+3]) div 9;
               gvalue:=(p[s2]+p[s2-3]+p[s2+3]+p1[s2]+p1[s2-3]+p1[s2+3]+
                        p2[s2]+p2[s2-3]+p2[s2+3]) div 9;
               bvalue:=(p[s1]+p[s1-3]+p[s1+3]+p1[s1]+p1[s1-3]+p1[s1+3]+
                        p2[s1]+p2[s1-3]+p2[s1+3]) div 9;
             end;
          else
            begin
              rvalue:=p[s3];
              gvalue:=p[s2];
              bvalue:=p[s1];
            end;
        end;
        p[s3]:=rvalue;
        p[s2]:=gvalue;
        p[s1]:=bvalue;
      end;
    end;
  end;
  tmpbitmap.free;
end;// 直方图均衡
// darkness为黑度，即均衡输出亮度的下限。
// brightness为白度，为均衡输出亮度的上限。
// 可以参考PHOTOSHOP类似功能的概念。
// x1,y1,x2,y2为处理的区域。
procedure grayextend(mybitmap: tbitmap; darkness,brightness: byte;
                     x1,y1,x2,y2: integer);
var
  his: array [0..255,1..3] of real;
  ihis: array [0..255,1..3] of extended;
  hiseq: array [0..255,1..3] of integer;
  sum: extended;
  i,j: integer;
  thew,theh: integer;
  p: pbytearray;
  sumreal: array [1..3] of real;
  rate: real;
  maxnum,minnum: integer;
begin
  for i:=0 to 255 do
    for j:=1 to 3 do
      ihis[i,j]:=0;
  sum:=0;
  with mybitmap do
  begin
    thew:=width;
    theh:=height;
    if (x1=x2) or (y1=y2) then
    begin
      x1:=1;
      y1:=1;
      x2:=thew-1;
      y2:=theh-1;
    end
    else
    begin
      minnum:=min(y1,y2);
      maxnum:=max(y1,y2);
      y1:=minnum;
      y2:=maxnum;
      minnum:=min(x1,x2);
      maxnum:=max(x1,x2);
      x1:=minnum;
      x2:=maxnum;
    end;
    if x1<1 then x1:=1;
    if y1<1 then y1:=1;
    if x2>thew-1 then x2:=thew-1;
    if y2>theh-1 then y2:=theh-1;
    for i:=y1 to y2 do
    begin
      p:=scanline[i];
      for j:=x1 to x2 do
      begin
        ihis[p[j*3],1]:=ihis[p[j*3],1]+i*i;
        ihis[p[j*3+1],2]:=ihis[p[j*3+1],2]+i*i;
        ihis[p[j*3+2],3]:=ihis[p[j*3+2],3]+i*i;
        sum:=sum+i*i;
      end;
    end;
    for i:=0 to 255 do
      for j:=1 to 3 do his[i,j]:=ihis[i,j]/sum;
    for i:=0 to 255 do
    begin
      sumreal[1]:=0;
      sumreal[2]:=0;
      sumreal[3]:=0;
      for j:=0 to i do
      begin
        sumreal[1]:=sumreal[1]+his[j,1];
        sumreal[2]:=sumreal[2]+his[j,2];
        sumreal[3]:=sumreal[3]+his[j,3];
      end;
      rate:=1;
      hiseq[i,1]:=round((brightness-darkness)*sumreal[1]*rate+darkness);
      hiseq[i,2]:=round((brightness-darkness)*sumreal[2]*rate+darkness);
      hiseq[i,3]:=round((brightness-darkness)*sumreal[3]*rate+darkness);
    end;
    for i:=y1 to y2 do
    begin
      p:=scanline[i];
      for j:=x1 to x2 do
      begin
        p[j*3]:=hiseq[p[j*3],1];
        p[j*3+1]:=hiseq[p[j*3+1],2];
        p[j*3+2]:=hiseq[p[j*3+2],3];
      end;
    end;
  end;  // end of with
end;