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如何遍历.gif图像中的每个像素?

system.drawing c#

14

NoCarrier · 技术社区 · 17 年前

我需要通过一个.gif图像,确定每个像素的RGB值,x和y坐标。有人能给我一个如何实现这一点的概述吗?(方法、要使用的名称空间等)

2 回复 | 直到 14 年前

1

27

LarsTech 8 年前

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;

namespace BitmapReader
{
    class Program
    {
        static void Main(string[] args)
        {
            //Try a small pic to be able to compare output, 
            //a big one to compare performance
            System.Drawing.Bitmap b = new 
                System.Drawing.Bitmap(@"C:\Users\vinko\Pictures\Dibujo2.jpg"); 
            doSomethingWithBitmapSlow(b);
            doSomethingWithBitmapFast(b);
        }

        public static void doSomethingWithBitmapSlow(System.Drawing.Bitmap bmp)
        {
            for (int x = 0; x < bmp.Width; x++)
            {
                for (int y = 0; y < bmp.Height; y++)
                {
                    Color clr = bmp.GetPixel(x, y);
                    int red = clr.R;
                    int green = clr.G;
                    int blue = clr.B;
                    Console.WriteLine("Slow: " + red + " " 
                                       + green + " " + blue);
                }
            }
        }

        public static void doSomethingWithBitmapFast(System.Drawing.Bitmap bmp)
        {
            Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);

            System.Drawing.Imaging.BitmapData bmpData =
                bmp.LockBits(rect, 
                    System.Drawing.Imaging.ImageLockMode.ReadOnly,
                    bmp.PixelFormat);

            IntPtr ptr = bmpData.Scan0;

            int bytes = bmpData.Stride * bmp.Height;
            byte[] rgbValues = new byte[bytes];

            System.Runtime.InteropServices.Marshal.Copy(ptr, 
                           rgbValues, 0, bytes);

            byte red = 0;
            byte green = 0;
            byte blue = 0;

            for (int x = 0; x < bmp.Width; x++)
            {
                for (int y = 0; y < bmp.Height; y++)
                {
                    //See the link above for an explanation 
                    //of this calculation
                    int position = (y * bmpData.Stride) + (x * Image.GetPixelFormatSize(bmpData.PixelFormat)/8); 
                    blue = rgbValues[position];
                    green = rgbValues[position + 1];
                    red = rgbValues[position + 2];
                    Console.WriteLine("Fast: " + red + " " 
                                       + green + " " + blue);
                }
            }
            bmp.UnlockBits(bmpData);
        }
    }
}

2

9

Jon Skeet 17 年前

您可以使用加载图像 new Bitmap(filename) Bitmap.GetPixel 反复地这很慢,但很简单。(有关示例,请参见Vinko的回答。)

如果性能很重要,您可能希望使用 Bitmap.LockBits 和不安全代码。显然,这减少了您能够使用解决方案的位置(就信任级别而言)的数量,并且通常更为复杂-但这可能是一个问题更快。

3

0

mekb TanvirArjel 7 年前

如果您的gif未设置动画,请使用以下选项:

Image img = Image.FromFile("image.gif");

for (int x = 0; x < img.Width; x++)
{
    for (int y = 0; y < img.Height; y++)
    {
        // Do stuff here
    }
}

^{(未经测试)}

Image img = Image.FromFile("animation.gif");

FrameDimension frameDimension = new FrameDimension(img.FrameDimensionsList[0]);
int frames = img.GetFrameCount(frameDimension);

for (int f = 0; f < frames; f++)
{
    img.SelectActiveFrame(frameDimension, f);

    for (int x = 0; x < img.Width; x++)
    {
        for (int y = 0; y < img.Height; y++)
        {
            // Do stuff here
        }
    }
}

^{(未经测试)}