ImageResizer generate wrong width for the image

Question

I let users upload a banner with a minimum width of 400px. This image will then get a wide of 1110px. I try to upload images with the following sizes: 960x390, 410x410, 784x250. When i upload 784x250, the image get the same size 784x250 not the width, 1110px.

I use this:

        int Height;
        using (var Bmp = new Bitmap(str))
        {
            if (Bmp.Width < 400)
            {
                throw;
            }
            if (Bmp.Height < 150)
            {
                throw;
            }
            Height = Bmp.Height;
        }

        if (Height > 300)
        {
            Height = 300;
        }

        str.Position = 0;
        var ImageData = str.StreamToByteArray();

        var Settings = "width=1110;height="+ Height + ";format=jpg;mode=crop;"

        var Setting = new ResizeSettings(Settings);
        using (var Out = new MemoryStream())
        {
            using (var In = new MemoryStream(ImageData))
            {
                In.Seek(0, SeekOrigin.Begin);

                var I = new ImageJob(In, Out, Setting)
                {
                    CreateParentDirectory = false
                };
                I.Build();
            }

            Out.Position = 0;

            // Upload to blob
        }

(str contains a stream with the image)

I want the image to be 1110px wide and max 300px high. Whats wrong?

I'm going to hazard a guess that this is the culprit: "mode=crop;" — Darren Gourley
– Darren Gourley, Commented Nov 10, 2015 at 14:06

Lilith River · Accepted Answer · 2015-11-10 16:33:02Z

2

ImageResizer does not upscale images unless you specifically ask for it via scale=both or scale=canvas. Upscaling is typically undesired.

Also, you can pass the stream directly to ImageJob and simplify your code significantly.

str.Seek(0, SeekOrigin.Begin);
var Out = new MemoryStream(8096);
new ImageJob(str, Out, new Instructions("width=1110;height="+ Height + ";format=jpg;mode=crop;scale=both")).Build();
Out.Seek(0, SeekOrigin.Begin);

answered Nov 10, 2015 at 16:33

Lilith River

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Comments

Oceans · Accepted Answer · 2015-11-10 14:58:41Z

1

The other sizes you tested each have a Bmp.Height > 300 which means the image requires to be cropped.
However when using an image size 784x250, the image doesn't require to be cropped. So you'll never re-size the image.

Assuming you wish to keep the image proportionally correct, you should first re-size the image to match the wanted width and afterwards crop the exceeding height if necessary.

var image = new Bitmap(str);

var ratio = (double)1110 / image.Width;

var newWidth = (int)(image.Width * ratio);
var newHeight = (int)(image.Height * ratio);

var newImage = new Bitmap(newWidth, newHeight);

Graphics.FromImage(newImage).DrawImage(image, 0, 0, newWidth, newHeight);
var bmp = new Bitmap(newImage);

if(bmp.Height > 300){
//Resize again using crop, like you did in your original code.
}

answered Nov 10, 2015 at 14:58

Oceans

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1 Comment

Lilith River Over a year ago

Keep in mind that Bitmap and Graphics instances are not garbage collected as they appear as 1kb (instead of 90mb) to the .NET GC. Thus this code, if called a few dozen times sequentially, will crash the server. Also, DrawImage uses a process-wide lock (unlike ImageResizer's FastScaling engine), so if there are concurrent requests, those large blocks of memory will be held for a very, very long time.

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