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Date Posted: 07:19:33 05/16/00 Tue
Author: Michel
Subject: Re: SmoothTransform
In reply to: Hans-Eric Grönlund 's message, "SmoothTransform" on 09:16:01 05/15/00 Mon


Hi Hans-Eric,

Thank you for reporting this. I have added it to my "to do" list. I will verify and correct this. The only thing that needs to be checked is to ensure that only valid pixels are accessed, as the convolution transform selects pixels from a 3x3 area in the source image.

Best regards,

Michel

> Hi,
>
> we discovered that TSmoothTransform (and the other
> transformations that derives from
> TConvolutionTransform) is leaving the four corner dots
> uncopied (in our case they become black although they
> originally were white).
>
> We traced the problem into
> TConvolutionTransform.ApplyOnDest and it's CopyBorder
> procedure. CopyBorder as I understand it is copying a
> 1 pixel border, leaving it untouched by the
> transformation (why?). Now the problem is that
> CopyBorder are missing the four corner dots. I made a
> small correction that seems to work fine. Here it is:
>
> procedure CopyBorder;
> var
> X, Y : LongInt;
> begin
> for Y := 0 to (Height-1) do
> begin
> if (Y = 0) or (Y = (Height-1)) then
> begin
> //
> //OLD CODE: for X := 1 to (Width-2) do
> //
> // The old code miss the corner pixels
> //
> for X := 0 to (Width-1) do
> begin
> { draw horizontal borders }
> Dest.Rgb[X, 0] :=
> Source.Rgb[X, 0];
> Dest.Rgb[X, Height-1] :=
> Source.Rgb[X, Height-1];
> end;
> end
> else
> begin
> { draw vertical borders }
> Dest.Rgb[0, Y] := Source.Rgb[0,
> Y];
> Dest.Rgb[Width-1, Y] :=
> Source.Rgb[Width-1, Y];
> end;
> end;
> end;

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