Code Lab - Box Blur Effect

[Whiterock 0]

Hello community,

I've just tried to make a simple box blur effect in pdn. My code is:

#region UICode
#endregion

void Render(Surface dst, Surface src, Rectangle rect)
{
// Delete any of these lines you don't need
Rectangle selection = this.EnvironmentParameters.GetSelection(src.Bounds).GetBoundsInt();
int CenterX = ((selection.Right - selection.Left) / 2)+selection.Left;
int CenterY = ((selection.Bottom - selection.Top) / 2)+selection.Top;
ColorBgra PrimaryColor = (ColorBgra)EnvironmentParameters.PrimaryColor;
ColorBgra SecondaryColor = (ColorBgra)EnvironmentParameters.SecondaryColor;
int BrushWidth = (int)EnvironmentParameters.BrushWidth;

ColorBgra CurrentPixel;
ColorBgra LeftPixel;
ColorBgra RightPixel;
ColorBgra AbovePixel;
ColorBgra BelowPixel;


for (int y = rect.Top + 1; y < rect.Bottom - 1; y++)
{
	for (int x = rect.Left + 1; x < rect.Right - 1; x++)
	{
	CurrentPixel = src[x,y];
	LeftPixel = src[x-1,y];
	AbovePixel = src[x,y-1];
	BelowPixel = src[x,y+1];
	RightPixel = src[x+1,y];

	CurrentPixel.R = (byte)((LeftPixel.R+AbovePixel.R+BelowPixel.R+RightPixel.R)/4);
	CurrentPixel.G = (byte)((LeftPixel.G+AbovePixel.G+BelowPixel.G+RightPixel.G)/4);
	CurrentPixel.B = (byte)((LeftPixel.B+AbovePixel.B+BelowPixel.B+RightPixel.B)/4);
	CurrentPixel.A = (byte)((LeftPixel.A+AbovePixel.A+BelowPixel.A+RightPixel.A)/4);

	dst[x,y] = CurrentPixel;
	}
}
}

But i don't know the reason, why it doesn't work correctly. It's so strange, because it's just working every 2y-coords.

I hope someone or BoltBait can help me:roll:

MfG whiterock

p.s: I'm from Austria

[Cookies 6]

for (int y = rect.Top + 1; y < rect.Bottom - 1; y++)
{
for (int x = rect.Left + 1; x < rect.Right - 1; x++)
{

should be

for (int y = rect.Top; y < rect.Bottom; y++)
{
for (int x = rect.Left; x < rect.Right; x++)
{

Edited January 9, 2011 by Cookies

[Tanel 7]

Render rect's coordinates don't always match those of canvas.

Thererefore y loop starting at y = rect.Top + 1 will cause unpredictable results.

You could work around though, by using coordinates from Rectangle selection :

for (int y = selection.Top + 1; y < selection.Bottom - 1; y++)

Someone will sure present a better solution.

[Whiterock 0]

Ok, lets see: Why can do a "+1" say the program, that it it should calucate each second y-coord/x coord ? (strange)

I will try it and infomate (? does this word exist) you if its working or not;)

MfG Whiterock ("MfG" menas in Austria, something like "With friendly Greetings")

[Cookies 6]

Render rect's coordinates don't always match those of canvas.

Thererefore y loop starting at y = rect.Top + 1 will cause unpredictable results.

You could work around though, by using coordinates from Rectangle selection :

for (int y = selection.Top + 1; y < selection.Bottom - 1; y++)

Someone will sure present a better solution.

I wouldn't do that, if its in an irregular selection (round, shaped) it will do it outside the selection that way

Ok, lets see: Why can do a "+1" say the program, that it it should calucate each second y-coord/x coord ? (strange)

I will try it and infomate (? does this word exist) you if its working or not;)

MfG Whiterock ("MfG" menas in Austria, something like "With friendly Greetings")

read this: http://www.boltbait....lp/tutorial.asp it explains it

edit: I guess your trying to avoid going "outside" the image, if so use

src.GetBilinearSampleClamped(x, y);

Edited January 11, 2011 by Cookies

[skyoxZ 0]

src[x+0,y+0] should also be in the Box.

[Whiterock 0]

src.GetBilinearSampleClamped(x, y);

How can i use ist?

[Cookies 6]

like this

CurrentPixel = src.GetBilinearSampleClamped(x, y);