Saving resized images with alpha is bigger than ImageMagick

[trivalik]

ImageSharp Encodersettings:

var encoder = new PngEncoder
{
    CompressionLevel = PngCompressionLevel.BestCompression,
    FilterMethod = PngFilterMethod.Adaptive,
    SkipMetadata = true
};

Use of Magick

magick mogrify -trim -strip +repage -path cropped *.png

[JimBobSquarePants]

I really do not understand what you expect me or anyone else to do with such little information.

Do better.

[trivalik]

Steps:

• I have an image with alpha channel and padding arround.
• I apply resize with Magick and also with the C# (see code below)
• comparing file size of cropped images --> Magick wins

#:package SixLabors.ImageSharp@3.1.12

// Compile & run with:
// dotnet run cropFiles.cs "inputFolder" "outputFolder"

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Processing;

if (args.Length < 2)
{
    Console.WriteLine("Usage: dotnet run <inputFolder> <outputFolder>");
    return;
}

string inputDir = args[0];
string outputDir = args[1];

Directory.CreateDirectory(outputDir);

var encoder = new PngEncoder
{
    CompressionLevel = PngCompressionLevel.BestCompression,
    FilterMethod = PngFilterMethod.Adaptive,
    SkipMetadata = true
};

foreach (var file in Directory.GetFiles(inputDir))
{
    using var image = Image.Load<Rgba32>(file);

    var bg = image[0, 0];

    int left = 0, right = image.Width - 1;
    int top = 0, bottom = image.Height - 1;

    bool IsBg(Rgba32 p) => p.Equals(bg);

    while (left < right && Enumerable.Range(0, image.Height).All(y => IsBg(image[left, y]))) left++;
    while (right > left && Enumerable.Range(0, image.Height).All(y => IsBg(image[right, y]))) right--;
    while (top < bottom && Enumerable.Range(0, image.Width).All(x => IsBg(image[x, top]))) top++;
    while (bottom > top && Enumerable.Range(0, image.Width).All(x => IsBg(image[x, bottom]))) bottom--;

    image.Mutate(ctx =>
        ctx.Crop(new Rectangle(left, top, right - left + 1, bottom - top + 1))
    );

    string outPath = Path.Combine(outputDir, Path.GetFileName(file));
    image.Save(outPath, encoder);
}

[JimBobSquarePants]

What image did you use?
What are the output dimensions?
What is the encoded color type of both output images?