CODEWITHSUNDEEP
c#
zmahir
zmahir

Reputation: 23

Same size Bitmaps yield byte arrays

When generating Bitmaps from a WebBrowser's DrawToBitmap() function, while using two images of the same size, why in certain instances, when converting the Bitmap to a byte array, do you have arrays of different sizes? The function I used:

public static byte[] ImageToByte(Image img)
{
    ImageConverter converter = new ImageConverter();
    return (byte[])converter.ConvertTo(img, typeof(byte[]));
}

From here there is a problem with the images I use. They are different, I use snapshots of http://www.google.com and http://www.google.co.uk. They both generate images with a size of {Width = 833 Height = 500}. However, the sizes of the byte arrays are 20072 and 24368 respectively.

Any ideas?

Thanks!

EDIT

Let me add some more information. The images are turned into BMPs. I'll attach some more of my janked up C# for you all to understand a bit more.

public void captureSnapshot(string url)
{
    this.url = url;
    var thr = new Thread(() =>
    {
        browser = new WebBrowser();
        browser.DocumentCompleted += snapshotEventCompleted;
        browser.Navigate(url);
        Application.Run();
    });

    thr.SetApartmentState(ApartmentState.STA);
    thr.Start();
}

public void snapshotEventCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
    int pageHeight = browser.Document.Body.ScrollRectangle.Height;
    int pageWidth = browser.Document.Body.ScrollRectangle.Width;
    snapshot = new Bitmap(pageWidth, pageHeight);
    browser.Size = new Size(pageWidth, pageHeight);
    browser.ScrollBarsEnabled = false;
    browser.DrawToBitmap(snapshot, new Rectangle(browser.Location.X, browser.Location.Y, pageWidth, pageHeight));
}

SOLVED:

So it turns out the function DrawToBitmap is not supported. womp

Upvotes: 0

Views: 254

Answers (3)

zmahir
zmahir

Reputation: 23

So turns out the function DrawToBitmap not supported.

Upvotes: 0

Thomas Levesque
Thomas Levesque

Reputation: 292345

It depends on the codec used to save the image. If it's PNG or JPG for instance, then the compression might produce outputs of different sizes for images of the same size. That's because large uniform areas are compressed much more efficiently than areas with lots of details.

Upvotes: 3

Mehran
Mehran

Reputation: 1449

It's because of something called Stride please take a look at this article : Image Stride

enter image description here

Two buffers that contain video frames with equal dimensions can have two different strides. If you process a video image, you must take the stride into account.

Upvotes: 2

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