Mega Code Archive
Simple TBitmap blur algorithm
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Title: Simple TBitmap blur algorithm
Question: How to blur a TBitmap.
Answer:
The algorithm is very simple. The value of every pixel in the bitmap is replaced by the sum of the pixels information around the taken pixel divided by 8 (because there are 8 pixels around one pixel). To avoid problems we skip the pixels on the first and the last line and on the first and the last column.
function blur(source:TBitmap):TBitmap;
var
x,y:integer;
tline, mline, bline:PByteArray;
begin
for y := 1 to source.Height - 2 do begin
tline := source.ScanLine[y-1];
mline := source.ScanLine[y];
bline := source.ScanLine[y+1];
for x := 1 to source.Width - 2 do begin
mline^[x*3] := (mline^[x*3 - 3] + mline^[x*3 + 3] +
tline^[x*3 - 3] + tline^[x*3 + 3] + tline^[x*3] +
mline^[x*3 - 3] + mline^[x*3 + 3] + mline^[x*3]) div 8;
mline^[x*3+1] := (mline^[x*3 - 2] + mline^[x*3 + 4] +
tline^[x*3 - 2] + tline^[x*3 + 4] + tline^[x*3+1] +
mline^[x*3 - 2] + mline^[x*3 + 4] + mline^[x*3+1]) div 8;
mline^[x*3+2] := (mline^[x*3 - 1] + mline^[x*3 + 5] +
tline^[x*3 - 1] + tline^[x*3 + 5] + tline^[x*3+2] +
mline^[x*3 - 1] + mline^[x*3 + 5] + mline^[x*3+2]) div 8;
end;
end;
result := source;
end;
Usage example:
image1.picture.bitmap := blur(image1.picture.bitmap);
where image1 is a TPicture object.
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