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POChecksum an image in Delphi
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  1. POChecksum an image in Delphi
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    copied!<p>I am trying to checksum an image, but it takes too long to give a result, tried add values, and Adler-32 but both finishes in a long time (approximately 2 seconds).</p> <p>Adding values:</p> <pre><code>Function Checksum_CountryFlag(Img : TPicture):Integer; var j, k, Checksum : Integer; begin Checksum := 0; For j := 0 to Img.Width do For k := 0 to Img.Height do If (((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 15577344) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 15311104) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 3816255) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 10526623) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 12303034) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 9013641)) Then begin Checksum := Checksum + Img.Bitmap.Canvas.Pixels[j,k]; end; Result := Abs(Checksum); end; </code></pre> <p>Adler-32:</p> <pre><code>Function Checksum_Adler32(Img : TPicture):Integer; var i,a,b,j,k : Integer; begin a := 1; b := 0; For j := 0 to Img.Width do For k := 0 to Img.Height do If (((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 15577344) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 15311104) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 3816255) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 10526623) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 12303034) And ((Img.Bitmap.Canvas.Pixels[j,k]) &lt;&gt; 9013641)) Then begin a := a + Img.Bitmap.Canvas.Pixels[j,k]; b := b + a; end; Result := Abs(a) + Abs(b); end; </code></pre> <p>As you see, i am trying to avoid some values (technical reasons). Maybe this what makes it takes too long, i don't know, any ideas for improving this algorithm ?</p>
 

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