Problem extracting full palette from 8bit image

[Sepharo]

Machine can more than handle this that's why I posted the question because it's so strange... Yes it does stall during the loop not during the bitsfrompixel Bits from pixel is just a simply switch anyway public static int BitsFromPixelFormat(PixelFormat pixelFormat) { switch (pixelFormat) { case PixelFormat.Format1bppIndexed: return 1; case PixelFormat.Format4bppIndexed: return 4; case PixelFormat.Format8bppIndexed: return 8; ... etc.

[Sepharo]

Here's a picture of my actual breakpoints... http://wwwp.mirror.waffleimages.com/files/13/13e214fd705683442d70081bb7c901230aac708a.png With the wya they are setup in the picture it takes a while to manually step through 256times but it reaches the end eventually and all is fine... But only because it took some time to do manually. If I remove the breakpoints on i < bmp.Palette.Entries.Length; and i++; the stall happens directly between int i=0; and return rgbArray; There isn't any further question in my mind that something is going wrong during that palette copying inside that loop. But the real question is why? This machine is a beast and the rest of the code is fine just for somereason 256 iterations of rgbArray[i].rgbRed = bmp.Palette.Entries[i].R; rgbArray[i].rgbGreen= bmp.Palette.Entries[i].G; rgbArray[i].rgbBlue = bmp.Palette.Entries[i].B; stalls the program for 30 seconds or so.

[Mark Salsbery]

Hmmm... Is this managed C++? If so, does optimizing the loop help any?

public static RGBQUAD[] RGBQUADFromColorArray(Bitmap bmp)
{
// Some programs as Axialis have problems with a reduced palette, so lets create a full palette
int bits = Tools.BitsFromPixelFormat(bmp.PixelFormat);

if (bits <= 8)
{
RGBQUAD[] rgbArray = new RGBQUAD[1 << bits];

  ColorPalette ^palette = bmp.Palette;
  array<Color>^palcolors = palette->Entries;
  for(int i=0; i < palcolors->Length; i++)
  {
     rgbArray\[i\].rgbRed = palcolors\[i\].R;
     rgbArray\[i\].rgbGreen= palcolors\[i\].G;
     rgbArray\[i\].rgbBlue = palcolors\[i\].B;
  }

  return rgbArray;

}

return 0;
}

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Mark Salsbery]

I'm wondering if it's reallocating/recreating a new palette every time the Palette property is accessed. Maybe the optimized loop I posted below will help :) Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Sepharo]

The language is C#

[Mark Salsbery]

You should be able to do the same thing. The point is, pull the Palette and Palette.Entries property accesses OUT of the loop and loop through the entries array only. Sorry I don't know the syntax - it should be simple for you I would think :) Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Mark Salsbery]

I'll take a WILD stab at the C# syntax LOL...

public static RGBQUAD[] RGBQUADFromColorArray(Bitmap bmp)
{
// Some programs as Axialis have problems with a reduced palette, so lets create a full palette
int bits = Tools.BitsFromPixelFormat(bmp.PixelFormat);

if (bits <= 8)
{
RGBQUAD[] rgbArray = new RGBQUAD[1 << bits];

  ColorPalette palette = bmp.Palette;
  Color\[\] palcolors = palette.Entries;
  for(int i=0; i < palcolors.Length; i++)
  {
     rgbArray\[i\].rgbRed = palcolors\[i\].R;
     rgbArray\[i\].rgbGreen= palcolors\[i\].G;
     rgbArray\[i\].rgbBlue = palcolors\[i\].B;
  }

  return rgbArray;

}

return 0;
}

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Sepharo]

Wow that worked... You're a lifesaver and a genius. I wouldn't have thought that could fix it either but I was willing to try anything, so thanks for suggesting what I thought didn't matter. :D

[Sepharo]

Yep you got it, same thing I translated your C++ to. In case you didn't see my above reply... You got it fixed thanks so much.

[Mark Salsbery]

Cool! I had no idea using the properties in the loop would be that slow! Good to know! :) Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder