前幾天碰上需要對(duì)bmp位圖進(jìn)行縮放的功能,
調(diào)用API函數(shù),雖然能實(shí)現(xiàn)位圖縮放,但是對(duì)有放大的效果好,縮小會(huì)造成失真,圖像上有花點(diǎn),讓人難以接受
,因?yàn)楸救艘郧皩W(xué)易語(yǔ)言,易語(yǔ)言有一段代碼,對(duì)bmp圖像縮放效果非常 好,
昨天抽空,把它翻譯成c++代碼了,經(jīng)驗(yàn)證,非常 好用,帖上代碼:
這一段是對(duì)寬度進(jìn)行縮放:
void __stdcall bmpsetH(unsigned char *bitmap,int h,unsigned char *bitmap2){int i,j,k,bitmapH1,bitmapH2,bitmapV1,bitmapV2,bitmapSize1,bitmapSize2,bitmapLen1,bitmapLen2;int startH1,startH2,R,G,B,R1,G1,B1; // 位圖寬1 ＝ 取字節(jié)集數(shù)據(jù) (位圖數(shù)據(jù), #整數(shù)型, 19)bitmapH1=*((int*)(bitmap+18)); bitmapV1=*((int*)(bitmap+22)); int redress1=bitmapH1%4; int bitmapNH1=bitmapH1*3+redress1; bitmapLen1=bitmapNH1*bitmapV1; bitmapSize1=bitmapLen1+54; int redress2=h%4; int bitmapNH2=h*3+redress2; bitmapLen2=bitmapNH2*bitmapV1; bitmapSize2=bitmapLen2+54; memcpy(bitmap2,bitmap,54); memcpy(bitmap2+2,&bitmapSize2,4); memcpy(bitmap2+18,&h,4); double Hval=(double)bitmapH1/h; double Hvala=0; int Hvalb=0,Hvalc=0; for (i=1;i<=bitmapV1;i++) { startH2=bitmapSize2-i*bitmapNH2; startH1=bitmapSize1-i*bitmapNH1; B1=bitmap[startH1]; G1=bitmap[startH1+1]; R1=bitmap[startH1+2]; for(j=1;j<=h;j++) { startH2=startH2+3; Hvala=Hvala+Hval; if (Hvala<1) { Hvalb=3; } else { Hvalc=Hvala; Hvalb=Hvalc*3; } startH1=bitmapSize1-i*bitmapNH1+Hvalb; B=(bitmap[startH1-3]+B1)/2; G=(bitmap[startH1-2]+G1)/2; R=(bitmap[startH1-1]+R1)/2; bitmap2[startH2-3]=B; bitmap2[startH2-2]=G; bitmap2[startH2-1]=R; B1=bitmap[startH1-3]; G1=bitmap[startH1-2]; R1=bitmap[startH1-1]; } Hvala=0; }}這一段是對(duì)高度進(jìn)行縮放:
void BmpSetV(unsigned char *bitmap,int v,unsigned char *bitmap2){ double Vval,Vvala=0; int i,j,Vvalb=0,bitH1,bitNH1,bitV1,redress,bitLen1,bitsize1,bitLen2,bitsize2;int start3=0,start2=0,start1=0,G1,B1,R1,R,G,B; bitH1=*((int*)(bitmap+18));bitV1=*((int*)(bitmap+22));redress=bitH1%4;bitNH1=bitH1*3+redress;bitLen1=bitNH1*bitV1;bitsize1=bitLen1+54;bitLen2=bitNH1*v;bitsize2=bitLen2+54;memcpy(bitmap2,bitmap,54);memcpy(bitmap2+2,&bitsize2,4);memcpy(bitmap2+22,&v,4);Vval=bitV1/(double)v;for (i=1;i<=bitH1;i++){ start3=bitsize1-bitNH1+i*3; B1=bitmap[start3-3]; G1=bitmap[start3-2]; R1=bitmap[start3-1]; for (j=1;j<=v;j++) { Vvala=Vvala+Vval; if (Vvala<1)Vvalb=1; else Vvalb=Vvala; start2=bitsize2-j*bitNH1+i*3; start1=bitsize1-Vvalb*bitNH1+i*3; if (Vvalb<bitV1) { start3=bitsize1-Vvalb*bitNH1-bitNH1+i*3; if(i==1) { bitmap2[start2-3]=bitmap[start1-3]; bitmap2[start2-2]=bitmap[start1-2];bitmap2[start2-1]=bitmap[start1-1]; } else { B=(B1+bitmap[start1-3])/2; G=(G1+bitmap[start1-2])/2; R=(R1+bitmap[start1-1])/2; bitmap2[start2-3]=B; bitmap2[start2-2]=G; bitmap2[start2-1]=R; B1=bitmap[start3-3]; G1=bitmap[start3-2]; R1=bitmap[start3-1]; } } else { bitmap2[start2-3]=bitmap[start1-3]; bitmap2[start2-2]=bitmap[start1-2];bitmap2[start2-1]=bitmap[start1-1]; } } Vvala=0;}}示例:
int main(int argc, char* argv[]){ unsigned char *bmp,*bmp2;bmp=(unsigned char*)malloc(1244214);bmp2=(unsigned char*)malloc(1244214);FILE *fp=fopen("D://開機(jī)畫面.bmp","rb");fread(bmp,1,304182,fp);fclose(fp); //bmpsetH(bmp,720,bmp2); // memcpy(bmp,bmp2,1244214);BmpSetV(bmp,290,bmp2); fp=fopen("D://開機(jī).bmp","wb");fwrite(bmp2,1,1244214,fp);fclose(fp); free(bmp);free(bmp2);return 0;}看到這確實(shí)不容易，這里武林網(wǎng)小編就為大家分享另一個(gè)代碼
// suofang.cpp : 定義控制臺(tái)應(yīng)用程序的入口點(diǎn)。//#include "stdafx.h"#include struct header{ short BM; unsigned int filesize; unsigned int recv; unsigned int offset; unsigned int bitmapheadlong; unsigned int bitmapwith; unsigned int bitmaphight; short bitmappageinfo; short bitperpixel; unsigned int compress; unsigned int bitmapsize; unsigned int levelresolution; unsigned int verticalresolution; unsigned int colourmap; unsigned int colourmapsize;}bitmapheader;#if 0 typedef struct tagBITMAPFILEHEADER { WORD bfType; // 位圖文件的類型，必須為BM(0-1字節(jié)) DWORD bfSize; // 位圖文件的大小，以字節(jié)為單位(2-5字節(jié)) WORD bfReserved1; // 位圖文件保留字，必須為0(6-7字節(jié)) WORD bfReserved2; // 位圖文件保留字，必須為0(8-9字節(jié)) DWORD bfOffBits; // 位圖數(shù)據(jù)的起始位置，以相對(duì)于位圖(10-13字節(jié)) // 文件頭的偏移量表示，以字節(jié)為單位 } BITMAPFILEHEADER; typedef struct tagBITMAPINFOHEADER{ DWORD biSize; // 本結(jié)構(gòu)所占用字節(jié)數(shù)(14-17字節(jié)) LONG biWidth; // 位圖的寬度，以像素為單位(18-21字節(jié)) LONG biHeight; // 位圖的高度，以像素為單位(22-25字節(jié)) WORD biPlanes; // 目標(biāo)設(shè)備的級(jí)別，必須為1(26-27字節(jié)) WORD biBitCount;// 每個(gè)像素所需的位數(shù)，必須是1(雙色),(28-29字節(jié)) // 4(16色)，8(256色)或24(真彩色)之一 DWORD biCompression; // 位圖壓縮類型，必須是 0(不壓縮),(30-33字節(jié)) // 1(BI_RLE8壓縮類型)或2(BI_RLE4壓縮類型)之一 DWORD biSizeImage; // 位圖的大小，以字節(jié)為單位(34-37字節(jié)) LONG biXPelsPerMeter; // 位圖水平分辨率，每米像素?cái)?shù)(38-41字節(jié)) LONG biYPelsPerMeter; // 位圖垂直分辨率，每米像素?cái)?shù)(42-45字節(jié)) DWORD biClrUsed;// 位圖實(shí)際使用的顏色表中的顏色數(shù)(46-49字節(jié)) DWORD biClrImportant;// 位圖顯示過(guò)程中重要的顏色數(shù)(50-53字節(jié)) } BITMAPINFOHEADER; typedef struct tagRGBQUAD { BYTE rgbBlue;// 藍(lán)色的亮度(值范圍為0-255) BYTE rgbGreen; // 綠色的亮度(值范圍為0-255) BYTE rgbRed; // 紅色的亮度(值范圍為0-255) BYTE rgbReserved;// 保留，必須為0 } RGBQUAD; #endifvoid scale(int srcwith,int srcheight,int destwith,int destheight){ }int _tmain(int argc, _TCHAR* argv[4000000]){ BITMAPFILEHEADER bmfHdr; BITMAPINFOHEADER bi,bi1; CFile file("d://pic1.bmp",CFile::modeRead); file.Read(&bmfHdr, sizeof(BITMAPFILEHEADER)); file.Read(&bi,sizeof(BITMAPINFOHEADER)); DWORD dwSize = (bi.biWidth*bi.biBitCount+31)/32*4*bi.biHeight; PBYTE pBuf = new BYTE[dwSize]; file.Read(pBuf,dwSize); file.Close(); ///////////////////////////////////////////////////////////////////////// file.Open("d://tmp1.bmp",CFile::modeCreate|CFile::modeReadWrite); memcpy(&bi1,&bi, sizeof(BITMAPINFOHEADER)); bi1.biWidth = 4000; //400->200 ,718->359 bi1.biHeight = 4000; //266->133,397->794 DWORD dwSize1 = (bi1.biWidth * bi1.biBitCount + 31)/32*4*bi1.biHeight; PBYTE pBuf1 = new BYTE[dwSize1]; BYTE *pSrc,*pDest; //ofstream file1("D://tmp.log");#if 0///////////////////////////////////最鄰近值采樣法（速度快）//////////////////////////////////////////////// float m_xscale,m_yscale; m_xscale = (float)bi.biWidth/(float)bi1.biWidth; m_yscale = (float)bi.biHeight/(float)bi1.biHeight; unsigned long k=0; for(int y = 0; y { for(int x=0; x { pSrc = pBuf+(int)(y*m_yscale)*bi.biWidth*3+(int)(x*m_xscale)*3; pDest = pBuf1+(int)(y*bi1.biWidth*3+x*3); memcpy(pDest,pSrc,3); //*(unsigned long*)pDest=k++; //*(unsigned long*)pDest=0x000000ff; } }////////////////////////////////////縮放結(jié)束///////////////////////////////////////////////#endif#if 1/////////////////////////////////////雙線性插值法（經(jīng)過(guò)優(yōu)化）///////////////////////////////////////////////////// int sw = bi.biWidth - 1, sh = bi.biHeight - 1, dw = bi1.biWidth - 1, dh = bi1.biHeight - 1; //源圖像寬度，目標(biāo)圖像寬度 int B, N, x, y; //計(jì)算出的目標(biāo)點(diǎn)對(duì)應(yīng)于源圖像中的浮點(diǎn)數(shù)橫坐標(biāo)N、縱坐標(biāo)B,目標(biāo)整數(shù)橫坐標(biāo)x、縱坐標(biāo)y int nPixelSize = bi.biBitCount/8; //像素大小 BYTE * pLinePrev, *pLineNext; //源圖像中的行開始坐標(biāo)和下一行開始坐標(biāo) //BYTE * pDest; BYTE * pA, *pB, *pC, *pD; //源圖像中最鄰近的四個(gè)點(diǎn) for ( int i = 0; i <= dh; ++i ) //高度遞增 { pDest = ( BYTE * )(pBuf1+bi1.biWidth*i*nPixelSize); y = i * sh / dh; N = dh - i * sh % dh; pLinePrev = ( BYTE * )(pBuf+bi.biWidth*y*nPixelSize); y++; pLineNext = ( N == dh ) ? pLinePrev : ( BYTE * )(pBuf+bi.biWidth*y*nPixelSize); for ( int j = 0; j <= dw; ++j ) //寬度遞增 { x = j * sw / dw * nPixelSize; B = dw - j * sw % dw; pA = pLinePrev + x; pB = pA + nPixelSize; pC = pLineNext + x; pD = pC + nPixelSize; if ( B == dw ) { pB = pA; pD = pC; } for ( int k = 0; k < nPixelSize; ++k ) *pDest++ = ( BYTE )( int )( ( B * N * ( *pA++ - *pB - *pC + *pD ) + dw * N * *pB++ + dh * B * *pC++ + ( dw * dh - dh * B - dw * N ) * *pD++ + dw * dh / 2 ) / (double)( dw * dh ) ); } }#endiffile.Write(&bmfHdr,sizeof(BITMAPFILEHEADER)); file.Write(&bi1,sizeof(BITMAPINFOHEADER)); file.Write(pBuf1,dwSize1); file.Close(); //==release p memory==delete pBuf;pBuf = NULL;delete pBuf1;pBuf1 = NULL;//==release p memory===if (pDest!=NULL){pDest = NULL;}//if (pSrc!=NULL)//{//pSrc = NULL;//}////////////////////////////////////////////////////////////////MessageBox("Test successful","Info",MB_OKCANCEL); return 0;}新聞熱點(diǎn)
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