Scaling performance problem

[James Dean]

I have tried a few different methods for scaling an image down but all
seem a bit on the slow side. Is there any way i can make this scaling
faster.......
Here is how i do it now.
To display my image at 1:2 zoom i have the following
xScaleFactor = 0.5
yScaleFactor = 0.5
public static Bitmap ScaleBitmap(Bit map inputBmp, double xScaleFactor,
double yScaleFactor) {
//Create a new bitmap object based on the input
Bitmap newBmp = new Bitmap((int)(in putBmp.Size.Wid th*xScaleFactor ),
(int)(inputBmp. Size.Height*ySc aleFactor),
PixelFormat.For mat32bppArgb);//Graphics.FromIm age doesn't
like Indexed pixel format

//Create a graphics object attached to the new bitmap
Graphics newBmpGraphics = Graphics.FromIm age(newBmp);
newBmpGraphics. InterpolationMo de = InterpolationMo de.HighQualityB icubic;

newBmpGraphics. ScaleTransform( (float)xScaleFa ctor, (float)yScaleFa ctor);
Rectangle drawRect = new Rectangle(0, 0, inputBmp.Size.W idth,
inputBmp.Size.H eight);

newBmpGraphics. DrawImage(input Bmp, drawRect, drawRect,
GraphicsUnit.Pi xel);
newBmpGraphics. Dispose();
return ConvertBitmap(n ewBmp, inputBmp.RawFor mat);
}

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[Marcin Grzębski]

Hi James,

From my point-of-view, you've got to choose:

A) QUALITY (InterpolationM ode.HighQuality Bicubic)
B) SPEED (InterpolationM ode.NearestNeig hbor)

....and from my practise i can say that speed difference
can be greater than 8x (depends on image size)

Regards

Marcin

I have tried a few different methods for scaling an image down but all
seem a bit on the slow side. Is there any way i can make this scaling
faster.......
Here is how i do it now.
To display my image at 1:2 zoom i have the following
xScaleFactor = 0.5
yScaleFactor = 0.5
public static Bitmap ScaleBitmap(Bit map inputBmp, double xScaleFactor,
double yScaleFactor) {
//Create a new bitmap object based on the input
Bitmap newBmp = new Bitmap((int)(in putBmp.Size.Wid th*xScaleFactor ),
(int)(inputBmp. Size.Height*ySc aleFactor),
PixelFormat.For mat32bppArgb);//Graphics.FromIm age doesn't
like Indexed pixel format

//Create a graphics object attached to the new bitmap
Graphics newBmpGraphics = Graphics.FromIm age(newBmp);
newBmpGraphics. InterpolationMo de = InterpolationMo de.HighQualityB icubic;

newBmpGraphics. ScaleTransform( (float)xScaleFa ctor, (float)yScaleFa ctor);
Rectangle drawRect = new Rectangle(0, 0, inputBmp.Size.W idth,
inputBmp.Size.H eight);

newBmpGraphics. DrawImage(input Bmp, drawRect, drawRect,
GraphicsUnit.Pi xel);
newBmpGraphics. Dispose();
return ConvertBitmap(n ewBmp, inputBmp.RawFor mat);
}

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