.NET GDI+ image size - file codec limitations
- by roygbiv
Is there a limit on the size of image that can be encoded using the image file codecs available from .NET?
I'm trying to encode images 4GB in size, but it simply does not work (or does not work properly i.e. writes out an unreadable file) with .bmp, .jpg, .png or the .tif encoders.
When I lower the image size to < 2GB it does work with the .jpg but not the .bmp, .tif or .png.
My next attempt would be to try libtiff because I know tiff files are meant for large images.
What is a good file format for large images? or am I just hitting the file format limitations?
Random r = new Random((int)DateTime.Now.Ticks);
int width = 64000;
int height = 64000;
int stride = (width % 4) > 0 ? width + (width % 4) : width;
UIntPtr dataSize = new UIntPtr((ulong)stride * (ulong)height);
IntPtr p = Program.VirtualAlloc(IntPtr.Zero, dataSize, Program.AllocationType.COMMIT | Program.AllocationType.RESERVE, Program.MemoryProtection.READWRITE);
Bitmap bmp = new Bitmap(width, height, stride, PixelFormat.Format8bppIndexed, p);
BitmapData bd = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, bmp.PixelFormat);
ColorPalette cp = bmp.Palette;
for (int i = 0; i < cp.Entries.Length; i++)
{
cp.Entries[i] = Color.FromArgb(i, i, i);
}
bmp.Palette = cp;
unsafe
{
for (int y = 0; y < bd.Height; y++)
{
byte* row = (byte*)bd.Scan0.ToPointer() + (y * bd.Stride);
for (int x = 0; x < bd.Width; x++)
{
*(row + x) = (byte)r.Next(256);
}
}
}
bmp.UnlockBits(bd);
bmp.Save(@"c:\test.jpg", ImageFormat.Jpeg);
bmp.Dispose();
Program.VirtualFree(p, UIntPtr.Zero, 0x8000);
I have also tried using a pinned GC memory region, but this is limited to < 2GB.
Random r = new Random((int)DateTime.Now.Ticks);
int bytesPerPixel = 4;
int width = 4000;
int height = 4000;
int padding = 4 - ((width * bytesPerPixel) % 4);
padding = (padding == 4 ? 0 : padding);
int stride = (width * bytesPerPixel) + padding;
UInt32[] pixels = new UInt32[width * height];
GCHandle gchPixels = GCHandle.Alloc(pixels, GCHandleType.Pinned);
using (Bitmap bmp = new Bitmap(width, height, stride, PixelFormat.Format32bppPArgb, gchPixels.AddrOfPinnedObject()))
{
for (int y = 0; y < height; y++)
{
int row = (y * width);
for (int x = 0; x < width; x++)
{
pixels[row + x] = (uint)r.Next();
}
}
bmp.Save(@"c:\test.jpg", ImageFormat.Jpeg);
}
gchPixels.Free();
