图象处理问题

[ladofwind]

我的系统需要把以前的影像处理成要求的格式和大小,也就是A4 size, 200dpi ,用了程序:

Bitmap bmpSource = new Bitmap(((Bitmap)this.images[0]), 1653, 2338);

//Bitmap bmpSource = new Bitmap(((Bitmap)this.images[0]));

int iSourceWidth = bmpSource.Width;

int iSourceHeight = bmpSource.Height;

float fSourceHorResolution = bmpSource.HorizontalResolution;

float fSourceVerResolution = bmpSource.VerticalResolution;

//图象dpi

float fTargetHorResolution = 200;

float fTargetVerResolution = 200;

Bitmap bmpTarget = new Bitmap(1653, 2338);

Graphics g = Graphics.FromImage(bmpTarget);

g.DrawImage(bmpSource, 0, 0, iSourceWidth, iSourceHeight);

bmpTarget.SetResolution(fTargetHorResolution, fTargetVerResolution);

bmpTarget = TiffManager.ConvertTo1bbpIndexed(bmpTarget, (float)0.9);

bmpTarget.Save(filename, info, ep);



在setResolution后,图象清晰度失真,变得很粗,我怀疑是原来图象96dpi,现在程序转成200dpi会造成像素填充.



一张黑白图上,只改动dpi的话,会不会对图象质量造成影响?

[wuxing2006]

不改图像大小

[ladofwind]

什么意思?我是问改大dpi后清晰度会有失真吗?

[wood87654321]

当然会失真，这和用photoshop把一张320*240的图放大到640*480保存一个道理

[ladofwind]

那如何获得原始图象的dpi呢, 我现在读进来全变96了,说是windows的默认

System.Drawing.Image img = System.Drawing.Image.FromHbitmap(this.bmp.GetHbitmap());
float x = img.VerticalResolution;
float y = img.HorizontalResolution;
这样拿到的是x,y =96

this.bmp.Save(filename); 存出来其实是200 dpi

[ladofwind]

弄错了,读出来是200