Create Large PNG with .NET

Question

I want to create a single large PNG file from a set of PNGs (max 25 files of 4080 x 800 pixels each).

The result that I expect is a single PNG with all stacked images.

I wrote this code:

private void PngCreate(List<FileInfo> imageListRef, string basePathPng, string filenamePng, int counter)
{
    if (imageListRef.Count > 0)
    {
        try
        {
            List<int> imageHeights = new List<int>();
            int width = 0;
            int height = 0;

            foreach (FileInfo file in imageListRef)
            {
                System.Drawing.Image img = System.Drawing.Image.FromFile(file.FullName);
                width = img.Width;
                height += img.Height;
                img.Dispose();
            }

            Bitmap bigImage = new Bitmap(width, height);
            Graphics g = Graphics.FromImage(bigImage);

            int y = 0;

            foreach (FileInfo file in imageListRef)
            {
                System.Drawing.Image img = System.Drawing.Image.FromFile(file.FullName);

                g.DrawImage(img, new Point(0, y));
                y += img.Height;

                img.Dispose();
            }
            g.Dispose();

            if (!Directory.Exists(basePathPng))
                Directory.CreateDirectory(basePathPng);

            bigImage.Save(filenamePng, System.Drawing.Imaging.ImageFormat.Png);
            bigImage.Dispose();

        }
        catch (Exception ex)
        {
            debugLogger.Debug(ex.Message);
            throw ex;
        }
    }
}

But I run out of memory with the new size of bigImage (4080 x 20000). What could I do in this case?

I thought about reducing or compressing the resolution of the single image, but I do not know how to do this.

I do not want to lose the quality of the image.

yes...but in reality, the 25 images have all the same dimensions (4080 x 800). Should not be a problem. Thanks for the correction anyway. — Cosma Iaffaldano, Dec 28 '17 at 14:53
At what point you're getting the exception? Another recommendation would be to use the statement `using (var img = Image.FromFile(file.FullName)){...}` to avoid manually dispose the `img` object. — dcg, Dec 28 '17 at 14:56
Exactly when I instantiate a new bitmap object `Bitmap bigImage = new Bitmap(width, height);` — Cosma Iaffaldano, Dec 28 '17 at 15:00
I don't know why is that happening to you, I created a sample code creating a `Bitmap` with the same dimensions, save it to file and worked perfectly (no exceptions). — dcg, Dec 28 '17 at 15:23
The obvious question is, how much free memory do you have before starting your application? — Jonny, Dec 28 '17 at 15:25
@Jonny the address space is virtual so it is not as easy as how much free memory the system has. — Crowcoder, Dec 28 '17 at 15:27
Well, how about debugging a bit and finding out which dimensions are actually used when creating the bitmap? — Jonny, Dec 28 '17 at 15:30
Do what @Jonny says and see the actual `width` and `height` you're passing in — dcg, Dec 28 '17 at 15:32
Have a look at this thread https://stackoverflow.com/questions/29175585/what-is-the-maximum-resolution-of-c-sharp-net-bitmap — Jonny, Dec 28 '17 at 15:33
Now I'm in debug and the demensions of bigImage are 4080 x 20000 @Jonny — Cosma Iaffaldano, Dec 28 '17 at 15:35
Project > Properties > Build tab, untick the "Prefer 32-bit" checkbox. You don't prefer it. — Hans Passant, Dec 28 '17 at 15:36
[This is my configuration](https://www.dropbox.com/s/q2ad1pag2o7ixij/Capture.PNG?dl=0) — Cosma Iaffaldano, Dec 28 '17 at 15:40

Create Large PNG with .NET

0 Answers0