Gaussian Blur Filter (port of public domain BlitzMax code by Queller)

[DruggedBunny Participant]

Quick port of BlitzMax Gaussian Blur Filter by Queller.

The demo will load an image specified by you, apply gaussian blur of level 10 (edit ,10 parameter for more/less blur) and save to desktop with randomised name of GaussFilter_Test_RndULong.png.

Only briefly tested, fixed error noted in archive.org thread! Note that it operates on, and returns, RGBA8 format images. Use Pixmap.Convert on the result if you need different output.

Monkey

#Import "<std>" Using std.. ' ID: 2364 ' Author: Queller ' Date: 2008-11-26 17:10:55 ' Title: Gaussian Blur Filter ' Description: A true Gaussian blur filter ' http://www.blitzbasic.com/ '======== Example ======== Function Main () Local filename:String = "" Assert (filename <> "", "Input path to an image on your computer!") Local pix:Pixmap = GaussianBlur (Pixmap.Load (filename), 10) pix.Save (DesktopDir () + "GaussFilter_Test_" + RndULong () + ".png") End '====== Example Ends ====== Function GaussianBlur:Pixmap(tex:Pixmap, radius:Int) If radius <=0 Return tex If tex.Format <> PixelFormat.RGBA8 Then tex = tex.Convert (PixelFormat.RGBA8) Local texclone:Pixmap = tex.Copy() 'clone incoming texture Local filter:GaussianFilter = New GaussianFilter 'instantiate a new gaussian filter filter.radius = radius 'configure it Return filter.apply(tex, texclone) End Function Class GaussianFilter Field radius:Double Field kernel:Kernel Method apply:Pixmap(src:Pixmap, dst:Pixmap) kernel = makekernel(radius) convolveAndTranspose(kernel, src, dst, src.Width, src.Height, True) convolveAndTranspose(kernel, dst, src, dst.Height, dst.Width, True) dst = Null GCCollect() Return src End Method 'Make a Gaussian blur kernel. Method makekernel:Kernel(radius:Double) Local r:Int = Int(Ceil(radius)) Local rows:Int = r*2+1 Local matrix:Double[] = New Double[rows] Local sigma:Double = radius/3.0 Local sigma22:Double = 2*sigma*sigma Local sigmaPi2:Double = 2*Pi*sigma Local sqrtSigmaPi2:Double = Sqrt(sigmaPi2) Local radius2:Double = radius*radius Local total:Double = 0 Local index:Int = 0 For Local row:Int = -r To r Local distance:Double = Double(row*row) If (distance > radius2) matrix[index] = 0 Else matrix[index] = Double(Exp(-(distance/sigma22)) / sqrtSigmaPi2) total = total + matrix[index] index = index + 1 End If Next For Local i:Int = 0 Until rows matrix[i] = matrix[i]/total 'normalizes the gaussian kernel Next Return mkernel(rows, 1, matrix) End Method Function mkernel:Kernel(w:Int, h:Int, d:Double[]) Local k:Kernel = New Kernel k.width = w k.height = h k.data = d Return k End Function Method convolveAndTranspose(kernel:Kernel, in:Pixmap, out:Pixmap, width:Int, height:Int, alpha:Int) Local inba:UByte Ptr = in.Data Local outba:UByte Ptr = out.Data Local matrix:Double[] = kernel.getKernelData() Local cols:Int = kernel.getWidth() Local cols2:Int = cols/2 For Local y:Int = 0 Until height Local index:Int = y Local ioffset:Int = y*width For Local x:Int = 0 Until width Local r:Double = 0, g:Double = 0, b:Double = 0, a:Double = 0 Local moffset:Int = cols2 For Local col:Int = -cols2 To cols2 Local f:Double = matrix[moffset+col] If (f <> 0) Local ix:Int = x+col If ( ix < 0 ) ix = 0 Else If ( ix >= width) ix = width-1 End If Local rgb:Int = Cast <Int Ptr> (inba)[ioffset+ix] ' Was Int Ptr inba a = a + f *((rgb Shr 24) & $FF) b = b + f *((rgb Shr 16) & $FF) g = g + f *((rgb Shr 8) & $FF) r = r + f *(rgb & $FF) End If Next Local ia:Int If alpha = True Then ia = clamp(Int(a+0.5)) Else ia = $FF Local ir:Int =clamp( Int(r+0.5)) Local ig:Int = clamp(Int(g+0.5)) Local ib:Int = clamp(Int(b+0.5)) Cast <Int Ptr> (outba)[index] =((ia Shl 24) | (ib Shl 16) | (ig Shl 8) | (ir Shl 0)) ' Was Int Ptr outba index = index + height Next Next End Method End Class Kernel Field width:Int Field height:Int Field data:Double[] Method getKernelData:Double[]() Return data End Method Method getWidth:Int() Return width End Method Method getHeight:Int() Return height End Method End Function clamp:Int(val:Int) If val < 0 Return 0 ElseIf val > 255 Return 255 Else Return val EndIf End Function

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#Import "<std>"   Using std..   ' ID: 2364 ' Author: Queller ' Date: 2008-11-26 17:10:55 ' Title: Gaussian Blur Filter ' Description: A true Gaussian blur filter   ' http://www.blitzbasic.com/     '======== Example ========   Function Main ()   Local filename:String = "" Assert (filename <> "", "Input path to an image on your computer!") Local pix:Pixmap = GaussianBlur (Pixmap.Load (filename), 10) pix.Save (DesktopDir () + "GaussFilter_Test_" + RndULong () + ".png") End   '====== Example Ends ======   Function GaussianBlur:Pixmap(tex:Pixmap, radius:Int) If radius <=0 Return tex If tex.Format <> PixelFormat.RGBA8 Then tex = tex.Convert (PixelFormat.RGBA8) Local texclone:Pixmap = tex.Copy() 'clone incoming texture Local filter:GaussianFilter = New GaussianFilter 'instantiate a new gaussian filter filter.radius = radius 'configure it Return filter.apply(tex, texclone) End Function   Class GaussianFilter   Field radius:Double Field kernel:Kernel Method apply:Pixmap(src:Pixmap, dst:Pixmap) kernel = makekernel(radius) convolveAndTranspose(kernel, src, dst, src.Width, src.Height, True) convolveAndTranspose(kernel, dst, src, dst.Height, dst.Width, True) dst = Null GCCollect() Return src End Method   'Make a Gaussian blur kernel.   Method makekernel:Kernel(radius:Double) Local r:Int = Int(Ceil(radius)) Local rows:Int = r*2+1 Local matrix:Double[] = New Double[rows] Local sigma:Double = radius/3.0 Local sigma22:Double = 2*sigma*sigma Local sigmaPi2:Double = 2*Pi*sigma Local sqrtSigmaPi2:Double = Sqrt(sigmaPi2) Local radius2:Double = radius*radius Local total:Double = 0 Local index:Int = 0   For Local row:Int = -r To r Local distance:Double = Double(row*row) If (distance > radius2) matrix[index] = 0 Else matrix[index] = Double(Exp(-(distance/sigma22)) / sqrtSigmaPi2) total = total + matrix[index] index = index + 1 End If Next   For Local i:Int = 0 Until rows matrix[i] = matrix[i]/total 'normalizes the gaussian kernel Next   Return mkernel(rows, 1, matrix) End Method Function mkernel:Kernel(w:Int, h:Int, d:Double[]) Local k:Kernel = New Kernel k.width = w k.height = h k.data = d Return k End Function     Method convolveAndTranspose(kernel:Kernel, in:Pixmap, out:Pixmap, width:Int, height:Int, alpha:Int) Local inba:UByte Ptr = in.Data Local outba:UByte Ptr = out.Data Local matrix:Double[] = kernel.getKernelData() Local cols:Int = kernel.getWidth() Local cols2:Int = cols/2 For Local y:Int = 0 Until height Local index:Int = y Local ioffset:Int = y*width For Local x:Int = 0 Until width Local r:Double = 0, g:Double = 0, b:Double = 0, a:Double = 0 Local moffset:Int = cols2 For Local col:Int = -cols2 To cols2 Local f:Double = matrix[moffset+col] If (f <> 0) Local ix:Int = x+col If ( ix < 0 ) ix = 0 Else If ( ix >= width) ix = width-1 End If Local rgb:Int = Cast <Int Ptr> (inba)[ioffset+ix] ' Was Int Ptr inba a = a + f *((rgb Shr 24) & $FF) b = b + f *((rgb Shr 16) & $FF) g = g + f *((rgb Shr 8) & $FF) r = r + f *(rgb & $FF) End If Next Local ia:Int If alpha = True Then ia = clamp(Int(a+0.5)) Else ia = $FF Local ir:Int =clamp( Int(r+0.5)) Local ig:Int = clamp(Int(g+0.5)) Local ib:Int = clamp(Int(b+0.5)) Cast <Int Ptr> (outba)[index] =((ia Shl 24) | (ib Shl 16) | (ig Shl 8) | (ir Shl 0)) ' Was Int Ptr outba index = index + height Next Next End Method End   Class Kernel   Field width:Int Field height:Int Field data:Double[] Method getKernelData:Double[]() Return data End Method Method getWidth:Int() Return width End Method Method getHeight:Int() Return height End Method   End   Function clamp:Int(val:Int) If val < 0 Return 0 ElseIf val > 255 Return 255 Else Return val EndIf End Function

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