README.md

C#/.NET6.0 Script to convert images

Converts from any type that is readable by Image.FromFile() to any of {BMP, JPG, PNG}

usage:

ImageConverter.exe {BMP, JPG, PNG} <files>

Dependencies: System.Drawing.Common

ImageConverter.cs

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

namespace ImageConverter
{
    class Program
    {
        enum ImageFormat { BMP, JPG, PNG, INVALID }

        static void Main(string[] args)
        {
            System.Drawing.Imaging.ImageFormat outputFormat;
            
            if (!Enum.TryParse(typeof(ImageFormat), args.First(), out object outputTypeObj))
            {
                Console.WriteLine($"Specify output-format as first argument, supported: {string.Join(',', Enum.GetValues(typeof(ImageFormat)))}");
                Environment.Exit(1);
            }

            IEnumerable<string> images = args[1] == "*"
                ? Directory.EnumerateFiles(Environment.CurrentDirectory, "*.png", SearchOption.TopDirectoryOnly)
                    .Concat(Directory.EnumerateFiles(Environment.CurrentDirectory, "*.jpg", SearchOption.TopDirectoryOnly))
                    .Concat(Directory.EnumerateFiles(Environment.CurrentDirectory, "*.bmp", SearchOption.TopDirectoryOnly))
                : new List<string>(args[1..]);
                outputFormat = ToGDIImageFormat((ImageFormat)outputTypeObj);

            foreach (var path in images)
            {
                if (!File.Exists(path))
                {
                    Console.WriteLine($"Bad input arg: {path}");
                    Environment.Exit(1);
                }

                try
                {
                    Image image = Image.FromFile(path);
                    var inputFormat = image.RawFormat;
                    if (inputFormat != outputFormat)
                        image.Save(Path.ChangeExtension(path, ToExtension(ToImageFormat(outputFormat))), outputFormat);
                }
                catch (Exception e)
                {
                    Console.WriteLine($"Could not convert {path} to {ToImageFormat(outputFormat)}");
                    Console.WriteLine(e.ToString());
                    Environment.Exit(1);
                }                
            }
            Environment.Exit(0);
        }

        private static string ToExtension(ImageFormat format) => format switch
        {
            ImageFormat.BMP => ".bmp",
            ImageFormat.PNG => ".png",
            ImageFormat.JPG => ".jpg",
            _ => throw new NotImplementedException($"imageFormat {format} was not implemented because of laziness")
        };

        private static ImageFormat ToImageFormat(System.Drawing.Imaging.ImageFormat gdi_imageFormat)
        {
            if (gdi_imageFormat == System.Drawing.Imaging.ImageFormat.Bmp)
                return ImageFormat.BMP;
            else if (gdi_imageFormat == System.Drawing.Imaging.ImageFormat.Jpeg)
                return ImageFormat.JPG;
            else if (gdi_imageFormat == System.Drawing.Imaging.ImageFormat.Png)
                return ImageFormat.PNG;
            else
                return ImageFormat.INVALID;
        }

        private static System.Drawing.Imaging.ImageFormat ToGDIImageFormat(ImageFormat format) => format switch
        {
            ImageFormat.BMP => System.Drawing.Imaging.ImageFormat.Bmp,
            ImageFormat.JPG => System.Drawing.Imaging.ImageFormat.Jpeg,
            ImageFormat.PNG => System.Drawing.Imaging.ImageFormat.Png,
            _ => throw new NotImplementedException($"imageFormat {format} was not implemented because of laziness")
        };
    }
}