位图的颜色转换

[yflc]

24位转成256色和16色，怎么转？

[yflc]

help

[zhlmnet2003]

24bit to 16bit

red = (truecolor>>8)&0xf800;
green = (truecolor>>5)&0x7e0;
blue = (truecolor>>3)&0x1f;
hicolor=red|green|blue;

[yflc]

有没有直接对象素的RGB进行转换的算法？

[用户 昵称]

HBITMAP LoadBitmap(
HINSTANCE hInstance, // handle to application instance
LPCTSTR lpBitmapName // address of bitmap resource name
);

BITMAPINFO * BitmapToDIB(HPALETTE hPal, // palette for color conversion
HBITMAP hBmp, // DDB for convert
int nBitCount, int nCompression) // format wanted
{
typedef struct
{
BITMAPINFOHEADER bmiHeader;
RGBQUAD bmiColors[256+3];
} DIBINFO;

BITMAP ddbinfo;
DIBINFO dibinfo;

// retrieve DDB information
if ( GetObject(hBmp, sizeof(BITMAP), & ddbinfo)==0 )
return NULL;

// fill out BITMAPINFOHEADER based on size and required format
memset(&dibinfo, 0, sizeof(dibinfo));

dibinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
dibinfo.bmiHeader.biWidth = ddbinfo.bmWidth;
dibinfo.bmiHeader.biHeight = ddbinfo.bmHeight;
dibinfo.bmiHeader.biPlanes = 1;
dibinfo.bmiHeader.biBitCount = nBitCount;
dibinfo.bmiHeader.biCompression = nCompression;

HDC hDC = GetDC(NULL); // screen DC
HGDIOBJ hpalOld;

if ( hPal )
hpalOld = SelectPalette(hDC, hPal, FALSE);
else
hpalOld = NULL;

// query GDI for image size
GetDIBits(hDC, hBmp, 0, ddbinfo.bmHeight, NULL, (BITMAPINFO *) & dibinfo, DIB_RGB_COLORS);

int nInfoSize = sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * GetDIBColorCount(dibinfo.bmiHeader);
int nTotalSize = nInfoSize + GetDIBPixelSize(dibinfo.bmiHeader);

BYTE * pDIB = new BYTE[nTotalSize];

if ( pDIB )
{
memcpy(pDIB, & dibinfo, nInfoSize);

if ( ddbinfo.bmHeight != GetDIBits(hDC, hBmp, 0, ddbinfo.bmHeight, pDIB + nInfoSize, (BITMAPINFO *) pDIB, DIB_RGB_COLORS) )
{
delete [] pDIB;
pDIB = NULL;
}
}

if ( hpalOld )
SelectObject(hDC, hpalOld);

ReleaseDC(NULL, hDC);

return (BITMAPINFO *) pDIB;
}

BOOL SaveDIBToBmp(const char* pFileName, const BITMAPINFO *pBMI, const BYTE *pBits)
{
if(pFileName==NULL){
return FALSE;
}

HANDLE handle = CreateFile(pFileName, GENERIC_WRITE, FILE_SHARE_READ,
NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

if(handle == INVALID_HANDLE_VALUE){
return FALSE;
}

BITMAPFILEHEADER bmFH;

int nHeadSize = sizeof(BITMAPINFOHEADER) +
sizeof(RGBQUAD) * GetDIBColorCount(pBMI->bmiHeader);

bmFH.bfType = 0x4D42;
bmFH.bfSize = nHeadSize + GetDIBPixelSize(pBMI->bmiHeader);
bmFH.bfReserved1 = 0;
bmFH.bfReserved2 = 0;
bmFH.bfOffBits = nHeadSize + sizeof(BITMAPFILEHEADER);

DWORD dwRead = 0;
WriteFile(handle, & bmFH, sizeof(bmFH), & dwRead, NULL);

if(pBits==NULL) // packed DIB
pBits = (BYTE *) pBMI + nHeadSize;

WriteFile(handle, pBMI, nHeadSize, & dwRead, NULL);
WriteFile(handle, pBits, GetDIBPixelSize(pBMI->bmiHeader), & dwRead, NULL);

CloseHandle(handle);

return TRUE;
}

给下面函数nBitCount 传递8表示保存为256色位图
BITMAPINFO * BitmapToDIB(HPALETTE hPal, // palette for color conversion
HBITMAP hBmp, // DDB for convert
int nBitCount, int nCompression) // format wanted

[gammergr]

hehe ,我做过这样的东东，256色的8个bit 中（RGB332）,
一个语句就搞定了：
return (P[tag].red/32*32+(P[tag].green/32)*4+P[tag].blue/64);

[zyl910]

有没有直接对象素的RGB进行转换的算法？
-------------------------------------------------
肯定没有
16色、256色都是调色版格式
必须考虑色彩量化处理


我以前用VB写的通过有序抖动保存各种格式的BMP（先进行相应抖动运算，再保存）的程序：
http://zyl910vb.51.net/vb/map/ddsfDIB.htm
右击连接，目标另存为
注意把下载后的*.zip.jpg改名成*.zip


这个程序是以前写的
刚学计算机图形学
不太懂
效率较低

[akiy]

如果用了gammergr的方法觉得效果不好
请联系我，不过是付费的！

[wrcluomo]

CCh1_1Doc* pDoc = GetDocument();// 获取文档
HDIB hDIB=pDoc->GetHDIB();
m_UnDo=CopyHandle(hDIB);
LPSTR lpDIB; // 指向DIB的指针
lpDIB = (LPSTR) ::GlobalLock((HGLOBAL) pDoc->GetHDIB());// 锁定DIB
if (lpDIB==NULL)return;
int NumColors;
NumColors=((LPBITMAPINFOHEADER)lpDIB)->biBitCount;
if(NumColors!=24)
{
MessageBox("不是24位真彩位图，不能操作。");
return;
}
BeginWaitCursor(); // 更改光标形状
LPSTR lpDIBBits;// 指向DIB图像开始处象素指针
LPSTR lpNewDIBBits;// 指向DIB灰度图图像开始处象素的指针
unsigned char * ired;
unsigned char * igreen;
unsigned char * iblack;
long i,j;// 循环变量
long lWidth,lHeight;// 图像宽度,图像高度
lWidth = ::DIBWidth(lpDIB); // 获取图像宽度
lHeight = ::DIBHeight(lpDIB);// 获取图像高度
lWidth =WIDTHBYTES(lWidth * 8);
lpDIBBits=::FindDIBBits(lpDIB);// 找到DIB图像象素起始位置&lpDIB[sizeof(BITMAPINFOHEADER)];
unsigned char * lpdest;
lpdest=(unsigned char *)::malloc(lHeight*lWidth);
int n=0;
for(j = 0; j <3*lWidth*lHeight; n++,j=j+3)//读取图像数据并转化成灰度
{
ired= (unsigned char*)lpDIBBits + j+2;
igreen = (unsigned char*)lpDIBBits+j+1;
iblack = (unsigned char*)lpDIBBits +j;
lpdest[n] =(unsigned char)(0.299*(*ired)+0.587*(*igreen)+0.114*(*iblack));
}
LPBITMAPINFOHEADER lpBI;//位图信息头
// 读取BITMAPINFO结构，初始化指针
lpBI = (LPBITMAPINFOHEADER)lpDIB;//[sizeof(BITMAPFILEHEADER)];
lpBI->biBitCount=8;
//设置256色灰度调色板
RGBQUAD *lpRGBquad;
lpRGBquad=(RGBQUAD *)&lpDIB[sizeof(BITMAPINFOHEADER)];//位图信息头后面为调色板
for (i = 0; i < 256; i++)
{
lpRGBquad[i].rgbRed =(unsigned char)i;// 读取红色分量
lpRGBquad[i].rgbGreen =(unsigned char)i;// 读取绿色分量
lpRGBquad[i].rgbBlue = (unsigned char)i;// 读取红色分量
lpRGBquad[i].rgbReserved = 0;// 保留位
}
lpNewDIBBits= ::FindDIBBits(lpDIB);// 找到DIB图像象素起始位置
unsigned char * lpSrc;
for (i=0;i<lHeight*lWidth;i++)//写灰度图像数据
{
lpSrc=(unsigned char*)lpNewDIBBits+i;
*lpSrc=lpdest[i];
}
::free((void *)lpdest);
pDoc->UpdateAllViews(NULL);//更新视图
::GlobalUnlock((HGLOBAL) pDoc->GetHDIB());// 解除锁定
EndWaitCursor();// 恢复光标