Ok, I've finally snapped

    I was just writing some code to manipulate a bitmap, something I need to do for my PhD (specifically, I'm converting YUV420P to RGB24). Anyhoo, the image isn't looking right, so before I go to sleep on it I thought I would dump the YUV values next to the RGB ones and see if I could eyeball the problem.

    I swear that as I was writing this I was thinking -- "I'll let the compiler optimise and write for readability". Do you think I succeeded? 

      for(x = 0; x < 320; x++)
    {
      for(y = 0; y < 240; y++)
	{
	  raster[((y + 480) * 640 * 2 + x + 640) * 3] = 
	    realfile[640 * 480 + (y * 320 + x)];
	  raster[((y + 480) * 640 * 2 + x + 640) * 3 + 1] = 
	    realfile[640 * 480 + (y * 320 + x)];
	  raster[((y + 480) * 640 * 2 + x + 640) * 3 + 2] = 
	    realfile[640 * 480 + (y * 320 + x)];

	  raster[((y + 480) * 640 * 2 + x + 640 + 320) * 3] = 
	    realfile[640 * 480 + (320 * 240) + (y * 320 + x)];
	  raster[((y + 480) * 640 * 2 + x + 640 + 320) * 3 + 1] = 
	    realfile[640 * 480 + (320 * 240) + (y * 320 + x)];
	  raster[((y + 480) * 640 * 2 + x + 640 + 320) * 3 + 2] = 
	    realfile[640 * 480 + (320 * 240) + (y * 320 + x)];
	}
    }


    Here's the image I get at the moment:



    See how the RGB image on the left isn't colorful enough? That pen there is lime green. Anyways, if anyone can see the problem and wants to give me a hint, that would be cool too.

    Update: It would seem that the terms YUV420, YUV420P, iYUV, and I420 are all interchangeable, to add to the fun.

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posted at: 17:46 | path: /phd | permanent link to this entry