I’m a newbie to dotnet, so sorry if this is a silly question.
I couldn’t find yet a solution, so I’d appreciate any hint.

There’s an open source program which get a png through http, first requests png format:

client.DefaultRequestHeaders.TryAddWithoutValidation("Accept", "image/png");

and stores it as ByteArray:

image1 = await response.Content.ReadAsByteArrayAsync()

I’d want to to two modifications with this png as byte array:

• First, draw a grid every x pixels
• Second, load another png file to use as a background image, and merge them.
  Then, replace the original ByteArray with the new ByteArray with these modifications.

I tried the easiest one, drawing the grid, using several ways, without success. I think the most correct one, despite it fails, is:

ImageSource image1_bitmap_frame = BitmapFrame.Create(new MemoryStream image1), BitmapCreateOptions.IgnoreImageCache, BitmapCacheOption.OnLoad);


WriteableBitmap combined_bitmap = new (image1.Clone());

// Draw a grid
for (int x = 0; x < combined_bitmap.PixelWidth; x +=50)
{
    for (int y = 0; y < combined_bitmap.PixelHeight; y++)
    {
        combined_bitmap.SetPixel(x,y, Colors.Black);
    }
}

But I get some errors:

• can’t convert System.Windows.Media.ImageSource to System.Windows.Media.Imaging.BitmapSource.
• there is no SetPoxel in WriteableBitmap

Could someone give me any hint about how to do this correctly?

Thanks in advance!