何将图片上下翻转?

来源：互联网发布：淘宝客服的工作时间编辑：程序博客网时间：2024/05/17 18:04

这是我修Computer Vision的作业，此源代码也示范出如何Pixel By Pixel的方式编辑图片以及如何读取indexd的bmp图片格式。

<%@ Page Language="C#" %>
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<%@ Import Namespace="System.Drawing" %>
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<%@ Import Namespace="System.Drawing.Imaging" %>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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/// <summary>
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/// Upside-down lena.bmp
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/// </summary>
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/// <remarks>
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/// .NET Framework 2.0 can't draw indexd pixel format directly.
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/// and will get
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/// "A Graphics object cannot be created from an image that "
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/// has an indexed pixel format." exception.
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/// So we have to make a temporary bitmap, and manually draw
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/// indexed pixel format to general bitmap.
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///</remarks>
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protected void Page_Load(object sender, EventArgs e) {
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// Bitmap uses System.Drawing namespace.
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Bitmap bmp = new Bitmap(Server.MapPath("lena.bmp"));
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// Size the _bmp to original bitmap's dimension.
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Bitmap _bmp = new Bitmap(bmp.Width, bmp.Height);
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// Uses temp _bmp to write on canvas.
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Graphics canvas = Graphics.FromImage(_bmp);
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// Draw the original indexed bitmap's content to the temp _bmp.
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// Paint the entire region of original bitmap to the temp _bmp.
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// Use the rectangle type to select area of source image.
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canvas.DrawImage(bmp, new Rectangle(0, 0, _bmp.Width, _bmp.Height), 0, 0, bmp.Width, bmp.Height, GraphicsUnit.Pixel);
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// Make temp _bmp to general bmp.
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bmp = _bmp;
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// Make a new bitmap for Upside-down.
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Bitmap bmpUpsideDown = new Bitmap(bmp.Width, bmp.Height);
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int r = 0, g = 0, b = 0; // R,G,B for Original bmp's RGB value.
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int avgY = (0 + bmp.Height) / 2; // avgY for average Y-axle value.
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int tarY = 0; // tarY for Upside-down Y-axle value.
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// Pixel by pixcel image processing.
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for (int x = 0; x < bmp.Width; x++) {
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for (int y = 0; y < bmp.Height; y++) {
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// Get RGB from original bitmap.
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r = bmp.GetPixel(x, y).R;
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g = bmp.GetPixel(x, y).G;
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b = bmp.GetPixel(x, y).B;
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// Cause (Origal y + Target y) /2 = Average y.
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tarY = 2 * avgY - y;
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// Write to new Upsite-down bitmap on specified pixel and RGB.
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bmpUpsideDown.SetPixel(x, tarY-1, Color.FromArgb(r, g, b));
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}
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}
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// Specify HTML's content type.
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Response.Clear();
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Response.ContentType = "image/bmp";
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// ImageFormat uses System.Drawing.Imaging namespace.
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// Must use ImageFormat.Jpeg. If use ImageFormat.Bmp,
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// you'll get "System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI+." error.
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bmpUpsideDown.Save(Response.OutputStream, ImageFormat.Jpeg);
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// You should always call the Dispose method to release
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// the Graphics and related resources created by the
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// FromImage method.
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_bmp.Dispose();
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bmp.Dispose();
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bmpUpsideDown.Dispose();
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canvas.Dispose();
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}
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</script>
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head runat="server">
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<title>Untitled Page</title>
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</head>
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<body>
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<form id="form1" runat="server">
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<div>
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</div>
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</form>
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</body>
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</html>
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