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Different Image Conversion Techniques

Well, so many image formats are available in the world. Like BMP (Bitmap),TIFF (Tagged Image File Format ), JPG/JPEG (Joint Photographic Experts Group),GIF (Graphic Interchange Format),PNG (Portable Network Graphics) etc.

I already mentioned that, my current multimedia project gave me a lot of chance to improve my coding practice as well as to learn a lot of new things, like GDI,GDI+,Cryptographic services etc.

One of the requirement for me was to “Convert images between different formats”. Nice requirement

And I’m  in bloody confident that, I can complete my work within a day. And I started my job. But…..:(

I searched MSDN and found IPicture, (Nice COM). By using that, I load the image,resized the image, cropped, etc.. Then the main requirement is in front of the curtain. “Image conversion.” and I use the IPicture::SaveAsFile(). Then only i noticed the method thoroughly. “Saves the picture’s data into a stream in the same format that it would save itself into a file. Bitmaps use the BMP file format, metafiles the WMF format, and icons the ICO format “

So again google the keyword..

Then one of my friend suggested this page..

Converting a BMP Image to a PNG Image http://msdn.microsoft.com/en-us/library/ms533837(VS.85).aspx

A very simple and nice article. by using that, we can convert the images between different formats.

code from MSDN

#include <windows.h>
#include <gdiplus.h>
#include <stdio.h>
using namespace Gdiplus;
int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
   UINT  num = 0;          // number of image encoders
   UINT  size = 0;         // size of the image encoder array in bytes

   ImageCodecInfo* pImageCodecInfo = NULL;

   GetImageEncodersSize(&num, &size);
   if(size == 0)
      return -1;  // Failure

   pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
   if(pImageCodecInfo == NULL)
      return -1;  // Failure

   GetImageEncoders(num, size, pImageCodecInfo);

   for(UINT j = 0; j < num; ++j)
   {
      if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
      {
         *pClsid = pImageCodecInfo[j].Clsid;
         free(pImageCodecInfo);
         return j;  // Success
      }
   }

   free(pImageCodecInfo);
   return -1;  // Failure
}

INT main()

{

   // Initialize GDI+.

   GdiplusStartupInput gdiplusStartupInput;

   ULONG_PTR gdiplusToken;

   GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

   CLSID   encoderClsid;

   Status  stat;

   Image*   image = new Image(L”Bird.bmp”);

   // Get the CLSID of the PNG encoder.

   GetEncoderClsid(L”image/png”, &encoderClsid);

   stat = image->Save(L”Bird.png”, &encoderClsid, NULL);

   if(stat == Ok)

      printf(“Bird.png was saved successfully\n”);

   else

      printf(“Failure: stat = %d\n”, stat);

   delete image;

   GdiplusShutdown(gdiplusToken);

   return 0;

}

 

For retrieving the Class Identifier for an Encoder we can use the following formats.

• image/bmp
• image/jpeg
• image/gif
• image/tiff
• image/png

So again curtain…

 

If you want to cross the sea, you have to step into the waves..

At first, the waves may distract you;

But gradually, you will subdue the fear within you.

For, no wave is mightier than the power of your mind.

 

for http://vctipsplusplus.wordpress.com/

BijU