Image as output!

[ancalime]

Hi,

I'm writing a program that should produce an image as the output...
Can anyone help?

[helios]

FreeImage and ImageMagick are the most popular free image manipulation libraries.

[Duthomhas]

There are also BMP and TGA files, two of the simplest file formats in existance.

For example, a TGA:

#include <fstream>
#include <string>
using namespace std;

typedef unsigned char byte;
typedef struct
  {
  byte red, green, blue;
  }
  RGB_t;

// It is presumed that the image is stored in memory as 
//   RGB_t data[ height ][ width ]
// where lines are top to bottom and columns are left to right
// (the same way you view the image on the display)

// The routine makes all the appropriate adjustments to match the TGA format specification.

bool write_truecolor_tga( const string& filename, RGB_t* data, unsigned width, unsigned height )
  {
  ofstream tgafile( filename.c_str(), ios::binary );
  if (!tgafile) return false;

  // The image header
  byte header[ 18 ] = { 0 };
  header[  2 ] = 1;  // truecolor
  header[ 12 ] =  width        & 0xFF;
  header[ 13 ] = (width  >> 8) & 0xFF;
  header[ 14 ] =  height       & 0xFF;
  header[ 15 ] = (height >> 8) & 0xFF;
  header[ 16 ] = 24;  // bits per pixel

  tgafile.write( (const char*)header, 18 );

  // The image data is stored bottom-to-top, left-to-right
  for (int y = height -1; y >= 0; y--)
  for (int x = 0; x < width; x++)
    {
    tgafile.put( (char)data[ (y * width) + x ].blue  );
    tgafile.put( (char)data[ (y * width) + x ].green );
    tgafile.put( (char)data[ (y * width) + x ].red   );
    }

  // The file footer. This part is totally optional.
  static const char footer[ 26 ] =
    "\0\0\0\0"  // no extension area
    "\0\0\0\0"  // no developer directory
    "TRUEVISION-XFILE"  // yep, this is a TGA file
    ".";
  tgafile.write( footer, 26 );

  tgafile.close();
  return true;
  }

Hope this helps.

[edit] BTW, I just typed this in... I didn't test it, so I may have typoed or otherwise made a really stoopid mistake somewhere. I don't think I did.... but just so you know. :-)

[helios]

Oh, how could I have forgotten the simpler formats?

RAW is even simpler, but it won't work if you need to create images of different sizes or bit depths.

[Mythios]

Just so he knows your code you forgot using namespace std; Just in case he gets confused why it won't build.

[Duthomhas]

Fixed. :-)


It depends on what you are doing. If all you want is something you can load in xv or paint, then a simple dump is fine. Otherwise I wholly agree with helios and also recommend using an imaging library.

[Mythios]

Wooo - your code worked fine by the way - i didn't realize you could do this so I gave it a little test. So cheers for the info heh