hi friends

I'm working with some large images, I want to tile them into small parts, so I use following lines in order to break my large image (a JPEG or BMP which may be up to 30000 x 30000 pixels in size), when my image is somehow smaller (almost smaller than 10000 x 10000) there is no problem, but when I have a bigger image I get an error in the first line

can you suggest my anything better? is there a good and secure way for tiling very large images using C#?



Bitmap bmpImage = new Bitmap(fname);// I get error here
int tile_width = bmpImage.Width / tile_x;
int tile_height = bmpImage.Height / tile_y;

//loop through all tiles
int counter = 0;
for (int y = 0; y < tile_y; y++)
{
for (int x = 0; x < tile_x; x++)
{

if (!File.Exists(_filename + (counter).ToString() + ".JPG"))//create only if file doesn't exist
{
Rectangle cropArea = new Rectangle(x * tile_width, y * tile_height, tile_width, tile_height);

Image img_cropped;
Bitmap bmpCrop = bmpImage.Clone(cropArea,
bmpImage.PixelFormat);
img_cropped = (Image)(bmpCrop);

EncoderParameter qualityParam =
new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 85L);

// Jpeg image codec
ImageCodecInfo jpegCodec = getEncoderInfo("image/jpeg");

if (jpegCodec == null)
return;

EncoderParameters encoderParams = new EncoderParameters(1);
encoderParams.Param[0] = qualityParam;

//img_cropped.Save(_filename + (counter).ToString() + ".BMP", ImageFormat.Bmp);
img_cropped.Save(_filename + (counter).ToString() + ".JPG", jpegCodec, encoderParams);
counter++;
MDIParent1.layerstatus = "Processing Layer...";
}
}
}


thanks

What is your Bitmap class, does it load the image when you call the constructor?

A 30000x30000 bmp is going to be something like 3-4GB, you probably just don't have enough memory to load the whole file at once.

Bitmap is a fairly easy filetype to parse so you could load the image in chunks yourself and then tile it out piece by piece, but jpg is quite a bit more difficult and I don't think any existing loader would be able to do a partial load like that (or maybe, I don't know).

Alternatively, you could just get a 64bit OS and 8-16GB of ram to be able to load it all at once.