Processing large images with Delphi for saving as .jpeg

Question

In Delphi 7, I have a library that uses the TCanvas component to output some information. The resulting image is about 4800*6000 pixels and I would like to print it and save it as .jpeg.

To achieve this, I created a TBitmap and gave its Canvas as parameter to the library and then I assigned the bitmap to the jpeg. Apparently, this is taking too much memory, because I am getting an exception when trying to set the bitmap's width and height, saying "Not enough storage is available to process this command."

// output to printer
Printer.BeginDoc();
doPrint(Printer.Canvas);
Printer.EndDoc();

// output in bmp.Canvas
bmp := TBitmap.Create;
bmp.Width := Printer.PageWidth;
bmp.Height := Printer.PageHeight; // <- BAM! Exception!
doPrint(bmp.Canvas);

// save as jpeg
jpg := TJPEGImage.Create;
jpg.Assign(bmp);
jpg.SaveToFile('...');

// free
bmp.Free();
jpg.Free();

What am I doing wrong? Could I save Printer.Canvas directly as a .jpeg file?

Edit: Updated image size approximation from 2000*2000 to 4800*6000

Answer 1

you should be able to process large bitmaps using TBitmap32 from Graphic32 (http://www.graphics32.org/wiki/)

Answer 2

You should set the pixelformat for the bmp to something before sizing up the bmp, as Ben Ziegler suggests. This makes all the difference.