11 lines
387 B
Text
11 lines
387 B
Text
//24-bpp P6 PPM solution:
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image:=File("lena.ppm","rb").read();
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start:=image.find("\n255\n")+5; // Get sizeof PPM header
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foreach n in ([start..image.len()-1,3]){ // Transform color triplets
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r,g,b:=image[n,3]; // Read colors stored in RGB order
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l:=(0.2126*r + 0.7152*g + 0.0722*b).toInt(); // Derive luminance
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image[n,3]=T(l,l,l);
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}
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File("lenaGrey.ppm","wb").write(image);
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