Question

I have to resize images exceeding a max size. Different methods I tried so far are not good enough:

1. System.Drawing.Image.GetThumbnailImage generates very poor quality images in general.
2. Playing with options like this one I can generate better images in quality but heavier than the original one.

Probably the second option (or something similar) is the best option and I would need to resize using the proper options.

Any advice?

EDIT
My option 2 was generating heavier images for some specific pictures. In general is working as expected so I’d say this is solved.

Answer 1

Try something like this:

public Bitmap Resize(Bitmap originalImage, int newWidth)
{
    int newHeight = (int)Math.Round(originalImage.Height * (decimal)newWidth / originalImage.Width, 0);
    var destination = new Bitmap(newWidth, newHeight);
    using (Graphics g = Graphics.FromImage(destination))
    {
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.PixelOffsetMode = PixelOffsetMode.HighQuality;
        g.DrawImage(originalImage, 0, 0, newWidth, newHeight);
    }
    return destination;
}