将图像大小调整为 2x2 像素为 4x4 像素，保持颜色相同

Question

请想象我有一个非常简单的棋盘图像。

在这里，我用字母表示图像作为像素：黑色像素“B”，白色像素“W”

这是起始的 2x2 像素图像：

BW
WB

我想调整图像大小，可以说按 2x 的比例给我：

BBWW
BBWW
WWBB
WWBB

或比例 4x

BBBBWWWW
BBBBWWWW
WWWWBBBB
WWWWBBBB

所以像素颜色根本不会以任何方式抖动。

我已经在 C# 中尝试过了，但图像一团糟，全部抖动，我需要学习如何在不抖动/颜色变化的情况下做到这一点。

到目前为止，这是我的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Text;

namespace PageTwine
{
    public partial class RandonGiff : System.Web.UI.Page
    {


        protected void Page_Load(object sender, EventArgs e)
        {

            // create 2x2 chequerboard:
            Bitmap oBitmap = new Bitmap(2, 2);
            Graphics oGraphic = Graphics.FromImage(oBitmap);

            // color black pixels (i think the default is black but this helps to explain)
            SolidBrush oBrush = new SolidBrush(Color.FromArgb(255, 255, 255));
            oGraphic.FillRectangle(oBrush, 0, 0, 1, 1);
            oGraphic.FillRectangle(oBrush, 1, 1, 1, 1);

            //color white pixels
            oBrush = new SolidBrush(Color.FromArgb(0, 0, 0));
            oGraphic.FillRectangle(oBrush, 0, 1, 1, 1);
            oGraphic.FillRectangle(oBrush, 1, 0, 1, 1);

            // expand to 4x4
            Bitmap result = new Bitmap(4, 4);
            using (Graphics graphics = Graphics.FromImage(result))
            {
                // I don't know what these settings should be :

                graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.NearestNeighbor;
                graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.None;

                //draw the image into the target bitmap 
                graphics.DrawImage(oBitmap, 0, 0, result.Width, result.Height);
            }

            //send image directly to the browser
            Response.ContentType = "image/gif";
            result.Save(Response.OutputStream, ImageFormat.Gif);

        }
    }

}

结果是抖动图像，但我需要干净清晰的棋盘效果。 请你帮帮我。

编辑：07/02/12

感谢到目前为止的建议，但我仍在搜索但没有找到解决方案。

我创建了一个演示页面，以便您可以亲自查看结果。

演示的 URL 为：

http://www. Leansoftware.net/servicedesk/publicadhoc/randomgif.aspx?columns=3&rows=3

该演示将创建一个棋盘格，其中初始列 x 行作为像素，然后放大为 300x300 像素的 gif 图像。

你会看到颜色扭曲/有点小——这是我试图解决的问题。

以下是演示的源代码：

using System;
using System.Collections.Generic;
using System.Web;
using System.IO;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Text;
using System.Linq;


    public partial class RandomGif : System.Web.UI.Page
    {
        public class Coordinates
        {
            public int x { get; set; }
            public int y { get; set; }
        }

        static Random rand = new Random();

        protected void Page_Load(object sender, EventArgs e)
        {
            // Output type gif
            int iwidth;
            int iheight;
            int bits;
            Response.ContentType = "image/gif";

            // Get parameters
            if (Request.QueryString["count"] != null)
            {
                bits = Convert.ToInt32(Request.QueryString["count"]);
                int square = Convert.ToInt32(Math.Ceiling(Math.Sqrt(bits + Math.Floor(bits / 4.0))));
                iwidth = square;
                iheight = square;
                bits = (square * square)-1;
            }
            else
                if (Request.QueryString["rows"] != null && Request.QueryString["columns"] != null)
                {
                    iwidth = Convert.ToInt32(Request.QueryString["columns"]);
                    iheight = Convert.ToInt32(Request.QueryString["rows"]);
                    bits = (iwidth * iheight);
                }
                else {
                    return;
                }
        if (bits > 1000){
        Response.Write("Please specify a grid <= 1000 pixels");
        return;
        }

            int plotCount = 0;

            //web safe colors : 00, 33, 66, 99, CC, FF;
            List<int> webSafeColor = new List<int>();
            webSafeColor.Add(0); //00
            webSafeColor.Add(51);//33
            webSafeColor.Add(102);//66
            webSafeColor.Add(153);//99
            webSafeColor.Add(204);//CC
            webSafeColor.Add(255);//FF

            // Create a structure to hold all possible coordinates
            var Grid = new List<Coordinates>();
            for (int xi = 1; xi <= iwidth; xi++)
            {
                for (int yi = 1; yi <= iheight; yi++)
                {
                    Grid.Add(new Coordinates { x = xi, y = yi });
                    plotCount++;
                }
            }

            //create a new Bitmap object
            Bitmap oBitmap = new Bitmap(iwidth, iheight);

            //create a new Graphics object, which will allow us to draw on our bitmap:
            Graphics oGraphic = Graphics.FromImage(oBitmap);


            //fill the image rectangle with n bits
            for (int i = 1; i <= bits; i++)
            {
                //Random rand = new Random();
                int row = rand.Next(Grid.Count());

                // random red
                int ircolor = webSafeColor[rand.Next(5)];

                // random green
                int igcolor = webSafeColor[rand.Next(5)];

                // random blue
                int ibcolor = webSafeColor[rand.Next(5)];

                Color randomColor = Color.FromArgb(ircolor, igcolor, ibcolor);
                SolidBrush oBrush = new SolidBrush(randomColor);
                oGraphic.FillRectangle(oBrush, Grid[row].x - 1, Grid[row].y - 1, 1, 1);

        // Delete this coordinate#
                Grid.Remove(Grid[row]);
            }

            // resize image
            Bitmap result = new Bitmap(300, 300);
            using (Graphics graphics = Graphics.FromImage(result))
            {
                //set the resize quality modes to high quality 
                graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.AssumeLinear;
                graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.NearestNeighbor;
                graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
                graphics.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.Half; 

                //draw the image into the target bitmap 
                graphics.DrawImage(oBitmap, 0, 0, result.Width, result.Height);
            }

            //send image directly to the browser
            Response.ContentType = "image/gif";
            result.Save(Response.OutputStream, ImageFormat.Gif);

        }
    }

如果您可以提出修改建议，我们可以尝试一下，看看是否可以解决问题。

谢谢理查德

Answer 1

这可能是 c# Draw 的重复项图像（缩放）到图形无法正确插值。修复？

您需要添加：

graphics.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.Half;

或者，您可以使用

graphics.DrawImage(oBitmap, 0, 0, result.Width * 2, result.Height * 2);

强制画笔填充而不会在右下图像边缘扭曲的情况下实现类似的效果。

更新：

添加用于使用自定义调色板创建索引图像的链接。
http://support.microsoft.com/kb/319061

Answer 2

使用：

System.Drawing.Drawing2D.InterpolationMode.NearestNeighbor;