Question

我有byte[]，我想使用ImageSharp库创建灰度图像。

这就是我现在正在做的事情：

byte[] arr = MnistReader.ReadTestData(); //this gives me byte[] with 784 pixel values

ImageSharp.Image image = new ImageSharp.Image(28, 28);

for (int i = 0; i < image.Height; i++)
{
    for (int j = 0; j < image.Width; j++)
    {
        int curPixel = j + i * image.Width;
        image.Pixels[curPixel].R = arr[curPixel];
        image.Pixels[curPixel].G = arr[curPixel];
        image.Pixels[curPixel].B = arr[curPixel];
    }
}

我想知道是否有更优雅的方式来做这件事？

Answer 1

你可以这样做：

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ContestLibrary
{
    public class Problem
    {
        delegate string StringDelegate(string s);

        static void Benchmark(string description, StringDelegate d, int times, string text)
        {
            Stopwatch sw = new Stopwatch();
            sw.Start();
            for (int j = 0; j < times; j++)
            {
                d(text);
            }
            sw.Stop();
            Console.WriteLine("{0} Ticks {1} : called {2} times.", sw.ElapsedTicks, description, times);
        }

        public static string ReverseXor(string s)
        {
            char[] charArray = s.ToCharArray();
            int len = s.Length - 1;

            for (int i = 0; i < len; i++, len--)
            {
                charArray[i] ^= charArray[len];
                charArray[len] ^= charArray[i];
                charArray[i] ^= charArray[len];
            }

            return new string(charArray);
        }

        public static string ReverseClassic(string s)
        {
            char[] charArray = s.ToCharArray();
            int len = s.Length-1;

            for (int i = 0; i < len; i++, len--)
            {
                char temp = charArray[len];
                charArray[len] = charArray[i];
                charArray[i] = temp;
            }
            return new string(charArray);
         }

        public static string StringOfLength(int length)
        {
            Random random = new Random();
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < length; i++)
            {
                sb.Append(Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65))));
            }
            return sb.ToString();
        }

        static void Main(string[] args)
        {

            int[] lengths = new int[] {1,10,100,1000, 10000, 100000};

            foreach (int l in lengths)
            {
                int iterations = 10000;
                string text = StringOfLength(l);
                Benchmark(String.Format("Classic (Length: {0})", l), ReverseClassic, iterations, text);
                Benchmark(String.Format("Xor (Length: {0})", l), ReverseXor, iterations, text);
                Console.WriteLine();    
            }
            Console.Read();
        }
    }
}

使用ImageSharp从byte []创建图像

1 个答案: