C#处理大图片

2009-03-03 05:19:55 347 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

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c#学习(2):大图片的特效处理与获取屏幕上任一点的rgb值这里的大图片是指3M左右的图片，笔者所做的图片特效大约分为两种，一种是通过picturebox控件的变换而实现的，这类特效较为简单，其效率与图片本身并无关系；第二类是通过数值计算，利用计时器控制图片像素的显示，分块显示图片，例如百叶窗特效，旋转特效，马赛克特效等，这类特效的效率与图片本身的大小有很大关系。下边通过百叶窗的实现详细讲述一下如何高效的实现此类特效。首先，打开一阅读详情

今天要用C#写个图片切割的软件（要求图片能够在picturebox中显示出来）因为要处理的图片过大（150M左右）所以出现了一些问题源代码如下
由于图片过大所以首先想到先发图片压缩再显示出来下面是一个图片压缩的类网上找的
/// <summary>
/// 压缩图片类
/// </summary>
class ImgGDI
{
public ImgGDI()
{
//构造函数
}

/// <summary>
/// Bitmap转换byte[]数组
/// </summary>
/// <param name="bmp"></param>
/// <returns></returns>
public byte[] Bmptobyte(Bitmap bmp)
{
MemoryStream ms = new MemoryStream();
bmp.Save(ms, ImageFormat.Jpeg);
ms.Flush();
byte[] buffer = ms.GetBuffer();
ms.Close();
return buffer;
}

/// <summary>
/// byte[]数组转换Bitmap
/// </summary>
/// <param name="buffer"></param>
/// <returns></returns>
public Bitmap bytetobmp(byte[] buffer)
{
MemoryStream ms = new MemoryStream();
ms.Write(buffer, 0, buffer.Length);
Bitmap bmp = new Bitmap(ms);
ms.Close();
return bmp;
}

/// <summary>
/// 返回默认图片
/// </summary>
/// <returns></returns>
public Bitmap getInstance()
{
Bitmap bmp = DefaultPic();
return bmp;
}

/// <summary>
/// 选取本地图片
/// </summary>
/// <param name="IMG"></param>
/// <returns></returns>
public Bitmap LocalIMG(string IMG)
{
FileStream fs = new FileStream(IMG, FileMode.Open);
Bitmap bmp = new Bitmap(fs);
fs.Close();
return bmp;
}

/// <summary>
/// 返回流状态图片
/// </summary>
/// <param name="Img"></param>
/// <returns></returns>
public Bitmap ImgFromBase64(string Img)
{
Bitmap bmp;
byte[] buffer = Convert.FromBase64String(Img);
if (buffer.Length > 0)
{
MemoryStream ms = new MemoryStream();
ms.Write(buffer, 0, buffer.Length);
bmp = new Bitmap(ms);
ms.Close();
return bmp;
}
else
{
bmp = DefaultPic();
return bmp;
}
}

/// <summary>
/// 默认图片
/// </summary>
/// <returns></returns>
private Bitmap DefaultPic()
{
FileStream fs = new FileStream(Application.StartupPath + @"\Goodr.jpg", FileMode.Open);
Bitmap bmp = new Bitmap(fs);
fs.Close();
return bmp;
}

/// <summary>
/// GDI压缩图片
/// </summary>
/// <param name="bmp">传入参数Bitmap</param>
/// <returns></returns>
public byte[] ImageGdi(Bitmap bmp)
{

MemoryStream ms = new MemoryStream();

if (bmp != null)
{
Bitmap t = new Bitmap(bmp);//这里有问题，当图片较小的时候没有问题（7、8M左右）当图片大的时候提示构造函数的参数无效
t.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
}
byte[] buffer;
ms.Flush();
if (ms.Length > 95000)
{
//buffer = ms.GetBuffer();
double new_width = 0;
double new_height = 0;

Image m_src_image = Image.FromStream(ms);
if (m_src_image.Width >= m_src_image.Height)
{
new_width = 1024;
new_height = new_width * m_src_image.Height / (double)m_src_image.Width;
}
else if (m_src_image.Height >= m_src_image.Width)
{
new_height = 768;
new_width = new_height * m_src_image.Width / (double)m_src_image.Height;
}

Bitmap bbmp = new Bitmap((int)new_width, (int)new_height, m_src_image.PixelFormat);
Graphics m_graphics = Graphics.FromImage(bbmp);
m_graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
m_graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
m_graphics.DrawImage(m_src_image, 0, 0, bbmp.Width, bbmp.Height);

ms = new MemoryStream();

bbmp.Save(ms, ImageFormat.Jpeg);
buffer = ms.GetBuffer();
ms.Close();

return buffer;
}
else
{
buffer = ms.GetBuffer();
ms.Close();
return buffer;
}
}

}
以下是我的调用代码
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
ImgGDI img = new ImgGDI();
Bitmap btp = img.LocalIMG("211.jpg");
byte[] bt = img.ImageGdi(btp);
Bitmap btpsmall = img.bytetobmp(bt);
pictureBox1.Image = (Image)btpsmall;

}

private void label1_Click(object sender, EventArgs e)
{

}
}
图片小的时候没有问题图片大的时候（150M）时就出现了上面注释那里出现的错误参数无效
请大家帮忙看看帮忙改下算法或者提出一种更好的算法谢谢

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