ImageLoad

MainForm.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ImageLoad
{
    public partial class MainForm : Form
    {
        Bitmap[] bitmaps;

        public MainForm()
        {
            InitializeComponent();
        }

        private void MainForm_Load(object sender, EventArgs e)
        {
            IEnumerable<FileInfo> resources = new DirectoryInfo("Resources").EnumerateFiles("*.png", SearchOption.AllDirectories);
            listView.Items.AddRange(resources.Select(selector => new ListViewItem(selector.Name)).ToArray());
            bitmaps = new Bitmap[resources.Count()];
            Parallel.ForEach(resources.Select((file, index) => new { file, index }), item => bitmaps[item.index] = new Bitmap(item.file.OpenRead())/*.Clone(new Rectangle(0, 0, 16, 16), PixelFormat.Canonical)*/);
        }

        private void listView_DrawItem(object sender, DrawListViewItemEventArgs e)
        {
            e.Graphics.DrawImageUnscaledAndClipped(bitmaps[e.ItemIndex], e.Bounds);
            if (e.State.HasFlag(ListViewItemStates.Selected)) Text = e.Item.Text;
            else if (e.State.HasFlag(ListViewItemStates.Focused)) Text = "";
        }
    }
}

MainForm.Designer.cs

namespace ImageLoad
{
    partial class MainForm
    {
        /// <summary>
        /// 必要なデザイナー変数です。
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// 使用中のリソースをすべてクリーンアップします。
        /// </summary>
        /// <param name="disposing">マネージ リソースを破棄する場合は true を指定し、その他の場合は false を指定します。</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows フォーム デザイナーで生成されたコード

        /// <summary>
        /// デザイナー サポートに必要なメソッドです。このメソッドの内容を
        /// コード エディターで変更しないでください。
        /// </summary>
        private void InitializeComponent()
        {
            this.listView = new System.Windows.Forms.ListView();
            this.SuspendLayout();
            // 
            // listView
            // 
            this.listView.Dock = System.Windows.Forms.DockStyle.Fill;
            this.listView.Location = new System.Drawing.Point(0, 0);
            this.listView.Name = "listView";
            this.listView.OwnerDraw = true;
            this.listView.Size = new System.Drawing.Size(284, 261);
            this.listView.TabIndex = 0;
            this.listView.TileSize = new System.Drawing.Size(20, 18);
            this.listView.UseCompatibleStateImageBehavior = false;
            this.listView.View = System.Windows.Forms.View.Tile;
            this.listView.DrawItem += new System.Windows.Forms.DrawListViewItemEventHandler(this.listView_DrawItem);
            // 
            // MainForm
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(284, 261);
            this.Controls.Add(this.listView);
            this.Name = "MainForm";
            this.Load += new System.EventHandler(this.MainForm_Load);
            this.ResumeLayout(false);

        }

        #endregion

        private System.Windows.Forms.ListView listView;
    }
}

Program.cs

using System;
using System.Windows.Forms;

namespace ImageLoad
{
    static class Program
    {
        /// <summary>
        /// アプリケーションのメイン エントリ ポイントです。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new MainForm());
        }
    }
}