问题描述

求图像进行缩放的c代码。

c代码，不是c++。
希望是比较完整的代码，而不是一个子程序。
感谢！

解决方案

建议你去看开源的项目，如 CXImage
一般都是使用类似的开源项目来实现的类似的功能，完全自己写缩放代码不太现实。特别是对缩放后的效果要求比较高时！

解决方案二：

我这好像有，比较老的代码了，具体在光盘库的那张光盘上记不清了。

解决方案三：

http://blog.csdn.net/trent1985/article/details/45150677

解决方案四：

这个是目前市面上公认的比较好的缩放算法：
private Bitmap ZoomLanczos2Apply(Bitmap srcBitmap, double k)
{
Bitmap src = new Bitmap(srcBitmap);
int width = src.Width;
int height = src.Height;
BitmapData srcData = src.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
byte* pS = (byte*)srcData.Scan0;
int w = (int)((double)width * k);
int h = (int)((double)height * k);
Bitmap dst = new Bitmap(w, h, PixelFormat.Format32bppArgb);
BitmapData dstData = dst.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
byte* d = (byte*)dstData.Scan0;
int offset = dstData.Stride - w * 4;
int x = 0, y = 0;
double p = 0, q = 0;
double n1 = 0, n2 = 0, n3 = 0, n4 = 0, nSum = 0;
int p0 = 0, p1 = 0, p2 = 0, p3 = 0, p4 = 0, gray = 0;
byte* temp = null;
double[] NP1 = new double[] { -0.00623896218505032, -0.0122238956025722, -0.0179556611741633, -0.0234353793884155, -0.028664425422539, -0.0336444239814841, -0.0383772438642046, -0.0428649922670393, -0.0471100088344975, -0.0511148594680326, -0.0548823299036605, -0.0584154190695433, -0.0617173322348938, -0.0647914739617815, -0.0676414408716196, -0.0702710142382982, -0.0726841524200902, -0.0748849831426012, -0.0768777956451566, -0.0786670327031274, -0.0802572825387739, -0.0816532706332581, -0.0828598514525135, -0.0838820000996894, -0.0847248039068906, -0.0853934539789171, -0.0858932367016755, -0.0862295252278804, -0.0864077709525887, -0.0864334949910196, -0.086312279671003, -0.0860497600522689, -0.0856516154846428, -0.0851235612170509, -0.0844713400690516, -0.0837007141764163, -0.0828174568220629, -0.0818273443634177, -0.0807361482670294, -0.0795496272610035, -0.0782735196155422, -0.0769135355615895, -0.0754753498572731, -0.0739645945115212, -0.0723868516738999, -0.0707476466993797, -0.0690524413963838, -0.0673066274661114, -0.0655155201407567, -0.0636843520278618, -0.0618182671676555, -0.0599223153098279, -0.0580014464157926, -0.0560605053920726, -0.0541042270600343, -0.0521372313667693, -0.0501640188415028, -0.048188966301476, -0.0462163228108206, -0.0442502058955092, -0.0422945980170336, -0.0403533433070252, -0.0384301445645995, -0.0365285605177724, -0.0346520033498648, -0.0328037364913793, -0.0309868726774121, -0.0292043722702325, -0.0274590418462525, -0.0257535330461864, -0.0240903416868009, -0.0224718071322479, -0.0209001119225812, -0.0193772816566703, -0.0179051851263444, -0.0164855346982315, -0.015119886939392, -0.013809643482501, -0.0125560521259855, -0.0113602081641975, -0.0102230559423803, -0.00914539063088284, -0.00812786021277406, -0.00717096767873418, -0.00627507342282205, -0.00544039783246632, -0.00466702406578012, -0.00395490100907222, -0.00330384640720963, -0.00271355015928674, -0.00218357777186753, -0.00171337396189679, -0.00130226640121749, -0.000949469594490465, -0.00065408888218426, -0.000415124560192089, -0.000231476107535702, -0.000101946513534946, -0 };
double[] NP2 = new double[] { 0.999794398630316, 0.999177779156011, 0.998150695261436, 0.996714069021198, 0.994869189802256, 0.992617712728975, 0.989961656713271, 0.986903402052547, 0.983445687598761, 0.979591607502511, 0.975344607536654, 0.9707084810045, 0.965687364238256, 0.960285731693901, 0.954508390649264, 0.948360475512591, 0.941847441749449, 0.934975059436304, 0.927749406449645, 0.920176861299994, 0.912264095620641, 0.904018066321406, 0.895446007418168, 0.886555421549337, 0.877354071190877, 0.867849969581877, 0.858051371373022, 0.847966763010743, 0.83760485287009, 0.826974561149762, 0.816085009542993, 0.804945510698284, 0.793565557484247, 0.781954812073053, 0.770123094857198, 0.758080373214511, 0.745836750136481, 0.733402452735159, 0.720787820644003, 0.708003294328147, 0.695059403319663, 0.68196675439345, 0.668736019699406, 0.655377924866579, 0.641903237094975, 0.628322753250659, 0.614647287979759, 0.600887661856885, 0.587054689583387, 0.573159168250756, 0.559211865684328, 0.545223508882287, 0.531204772564777, 0.517166267847729, 0.503118531055783, 0.489072012688425, 0.47503706655321, 0.461023939079635, 0.447042758826945, 0.433103526198797, 0.419216103377392, 0.405390204489315, 0.391635386014941, 0.37796103745288, 0.364376372250524, 0.350890419011333, 0.33751201298905, 0.324249787878619, 0.311112167913061, 0.298107360275149, 0.285243347832182, 0.272527882201696, 0.259968477155437, 0.247572402368387, 0.235346677519141, 0.223298066747373, 0.211433073473617, 0.199757935586031, 0.188278620998268, 0.177000823582037, 0.165929959477376, 0.155071163783102, 0.144429287629353, 0.13400889563358, 0.123814263740785, 0.113849377448258, 0.104117930414501, 0.0946233234514916, 0.0853686638988765, 0.0763567653781721, 0.0675901479244855, 0.059071038492763, 0.050801371835042, 0.0427827917446759, 0.0350166526629909, 0.0275040216433488, 0.0202456806670952, 0.0132421293054104, 0.00649358772061002 };
double[] NP3 = new double[] { 0.00649358772061002, 0.0132421293054104, 0.0202456806670952, 0.0275040216433488, 0.0350166526629909, 0.0427827917446759, 0.0508013718350421, 0.059071038492763, 0.0675901479244855, 0.0763567653781721, 0.0853686638988765, 0.0946233234514916, 0.104117930414501, 0.113849377448258, 0.123814263740785, 0.13400889563358, 0.144429287629353, 0.155071163783102, 0.165929959477376, 0.177000823582037, 0.188278620998268, 0.199757935586031, 0.211433073473617, 0.223298066747373, 0.235346677519141, 0.247572402368387, 0.259968477155437, 0.272527882201696, 0.285243347832182, 0.298107360275149, 0.311112167913061, 0.324249787878619, 0.33751201298905, 0.350890419011333, 0.364376372250524, 0.37796103745288, 0.391635386014941, 0.405390204489315, 0.419216103377392, 0.433103526198797, 0.447042758826944, 0.461023939079634, 0.475037066553209, 0.489072012688425, 0.503118531055783, 0.517166267847729, 0.531204772564777, 0.545223508882287, 0.559211865684328, 0.573159168250756, 0.587054689583387, 0.600887661856885, 0.614647287979759, 0.628322753250659, 0.641903237094975, 0.655377924866579, 0.668736019699406, 0.68196675439345, 0.695059403319663, 0.708003294328147, 0.720787820644003, 0.733402452735159, 0.745836750136481, 0.758080373214511, 0.770123094857198, 0.781954812073053, 0.793565557484247, 0.804945510698284, 0.816085009542993, 0.826974561149762, 0.837604852870089, 0.847966763010743, 0.858051371373022, 0.867849969581877, 0.877354071190877, 0.886555421549337, 0.895446007418168, 0.904018066321406, 0.912264095620641, 0.920176861299994, 0.927749406449646, 0.934975059436304, 0.941847441749449, 0.948360475512591, 0.954508390649264, 0.960285731693901, 0.965687364238256, 0.9707084810045, 0.975344607536654, 0.979591607502512, 0.983445687598761, 0.986903402052547, 0.989961656713271, 0.992617712728975, 0.994869189802256, 0.996714069021198, 0.998150695261436, 0.999177779156011, 0.999794398630316 };
double[] NP4 = new double[] { -0, -0.000101946513534946, -0.000231476107535702, -0.000415124560192089, -0.00065408888218426, -0.000949469594490465, -0.0013022664012175, -0.00171337396189679, -0.00218357777186754, -0.00271355015928674, -0.00330384640720965, -0.00395490100907222, -0.00466702406578012, -0.00544039783246632, -0.00627507342282205, -0.00717096767873415, -0.00812786021277406, -0.00914539063088281, -0.0102230559423803, -0.0113602081641975, -0.0125560521259855, -0.013809643482501, -0.015119886939392, -0.0164855346982315, -0.0179051851263444, -0.0193772816566703, -0.0209001119225812, -0.0224718071322479, -0.0240903416868009, -0.0257535330461864, -0.0274590418462525, -0.0292043722702326, -0.0309868726774121, -0.0328037364913794, -0.0346520033498648, -0.0365285605177724, -0.0384301445645995, -0.0403533433070252, -0.0422945980170336, -0.0442502058955092, -0.0462163228108205, -0.048188966301476, -0.0501640188415028, -0.0521372313667693, -0.0541042270600343, -0.0560605053920726, -0.0580014464157926, -0.0599223153098279, -0.0618182671676555, -0.0636843520278618, -0.0655155201407567, -0.0673066274661114, -0.0690524413963838, -0.0707476466993797, -0.0723868516738999, -0.0739645945115212, -0.0754753498572731, -0.0769135355615895, -0.0782735196155421, -0.0795496272610035, -0.0807361482670294, -0.0818273443634177, -0.0828174568220629, -0.0837007141764163, -0.0844713400690516, -0.0851235612170509, -0.0856516154846428, -0.0860497600522689, -0.086312279671003, -0.0864334949910196, -0.0864077709525887, -0.0862295252278804, -0.0858932367016755, -0.0853934539789171, -0.0847248039068906, -0.0838820000996894, -0.0828598514525135, -0.0816532706332581, -0.0802572825387739, -0.0786670327031274, -0.0768777956451566, -0.0748849831426012, -0.0726841524200902, -0.0702710142382982, -0.0676414408716196, -0.0647914739617815, -0.0617173322348938, -0.0584154190695433, -0.0548823299036604, -0.0511148594680326, -0.0471100088344975, -0.0428649922670393, -0.0383772438642045, -0.0336444239814841, -0.028664425422539, -0.0234353793884155, -0.0179556611741633, -0.0122238956025722, -0.00623896218505032 };
for (int j = 0; j < h; j++)
{
q = (double)j / (double)k;
y = (int)q;
q = Math.Abs(q - (double)y);
p0 = y * srcData.Stride;
y = y >= height ? height - 1 : y;
for (int i = 0; i < w; i++)
{
p = (double)i / (double)k;
x = (int)p;
p = Math.Abs(p - (double)x);
temp = d + i * 4 + j * dstData.Stride;
if (p != 0)
{
x = (x >= width - 3 ? width - 3 : x);
x = x < 1 ? 1 : x;
gray = (int)(p * 100.0) - 1;
gray = Math.Max(0, gray);
n1 = NP1[gray];
n2 = NP2[gray];
n3 = NP3[gray];
n4 = 1.0 - n1 - n2 - n3;// NP4[gray];
p2 = x * 4 + p0;
p1 = p2 - 4;
p3 = p2 + 4;
p4 = p2 + 8;
nSum = n1 + n2 + n3 + n4;
gray = (int)((n1 * (double)((pS + p1)[0]) + n2 * (double)((pS + p2)[0]) + n3 * (double)((pS + p3)[0]) + n4 * (double)((pS + p4)[0])));
gray = Math.Max(0, Math.Min(255, gray));
temp[0] = (byte)gray;
gray = (int)((n1 * (double)((pS + p1)[1]) + n2 * (double)((pS + p2)[1]) + n3 * (double)((pS + p3)[1]) + n4 * (double)((pS + p4)[1])));
gray = Math.Max(0, Math.Min(255, gray));
temp[1] = (byte)gray;
gray = (int)((n1 * (double)((pS + p1)[2]) + n2 * (double)((pS + p2)[2]) + n3 * (double)((pS + p3)[2]) + n4 * (double)((pS + p4)[2])));
gray = Math.Max(0, Math.Min(255, gray));
temp[2] = (byte)gray;
}
else
{
x = x >= width ? width - 1 : x;
gray = x * 4 + y * srcData.Stride;
temp[0] = (byte)(pS + gray)[0];
temp[1] = (byte)(pS + gray)[1];
temp[2] = (byte)(pS + gray)[2];
}
temp[3] = (byte)255;
}
}
for (int i = 0; i < w; i++)
{
p = (double)i / (double)k;
x = (int)p;
p = Math.Abs(p - (double)x);
x = x >= width ? width - 1 : x;
for (int j = 0; j < h; j++)
{
q = (double)j / (double)k;
y = (int)q;
q = Math.Abs(q - (double)y);
p0 = y * srcData.Stride;
temp = d + i * 4 + j * dstData.Stride;
if (q != 0)
{
y = y >= height - 3 ? height - 3 : y;
y = y < 1 ? 1 : y;
gray = (int)(q * 100.0) - 1;
gray = Math.Max(0, gray);
n1 = NP1[gray];
n2 = NP2[gray];
n3 = NP3[gray];
n4 = 1.0 - n1 - n2 - n3;// NP4[gray];
nSum = n1 + n2 + n3 + n4;
p2 = x * 4 + y * srcData.Stride;
p1 = p2 - srcData.Stride;
p3 = p2 + srcData.Stride;
p4 = p3 + srcData.Stride;
gray = (int)((n1 * (double)((pS + p1)[0]) + n2 * (double)((pS + p2)[0]) + n3 * (double)((pS + p3)[0]) + n4 * (double)((pS + p4)[0])));
gray = Math.Max(0, Math.Min(255, gray));
temp[0] = (byte)gray;
gray = (int)((n1 * (double)((pS + p1)[1]) + n2 * (double)((pS + p2)[1]) + n3 * (double)((pS + p3)[1]) + n4 * (double)((pS + p4)[1])));
gray = Math.Max(0, Math.Min(255, gray));
temp[1] = (byte)gray;
gray = (int)((n1 * (double)((pS + p1)[2]) + n2 * (double)((pS + p2)[2]) + n3 * (double)((pS + p3)[2]) + n4 * (double)((pS + p4)[2])));
gray = Math.Max(0, Math.Min(255, gray));
temp[2] = (byte)gray;
}
else
{
y = y >= height ? height - 1 : y;
gray = x * 4 + y * srcData.Stride;
temp[0] = (byte)(pS + gray)[0];
temp[1] = (byte)(pS + gray)[1];
temp[2] = (byte)(pS + gray)[2];
}
temp[3] = (byte)255;
}
}
src.UnlockBits(srcData);
dst.UnlockBits(dstData);
return dst;
}