Grayscale image: Difference between revisions
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=={{header|REXX}}== |
=={{header|REXX}}== |
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Note: REXX uses characters instead of binary for storing numbers, so there is no rounding (using |
Note: REXX uses decimal (characters) instead of binary for storing numbers, so there is no rounding (using |
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<br> store numbers is almost the same as using decimal floating point). |
<br> characters to store numbers is almost the same as using decimal floating point). |
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<lang rexx>/*REXX program converts a RGB (red─green─blue) image into a grayscale/greyscale image. |
<lang rexx>/*REXX program converts a RGB (red─green─blue) image into a grayscale/greyscale image.*/ |
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blue= '00 00 ff'x /*define the blue color (hexadecimal).*/ |
blue= '00 00 ff'x /*define the blue color (hexadecimal).*/ |
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@.= blue /*set the entire image to blue color.*/ |
@.= blue /*set the entire image to blue color.*/ |
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do col=1 for width |
do col=1 for width |
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do row=1 for height /* [↓] C2D convert char |
do row=1 for height /* [↓] C2D convert char ───► decimal*/ |
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r= |
r= left(@.col.row, 1) ; r= c2d(r) /*extract the component red & convert.*/ |
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g=substr(@.col.row, 2, 1) ; g=c2d(g) |
g= substr(@.col.row, 2, 1) ; g= c2d(g) /* " " " green " " */ |
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b= right(@.col.row, 1) ; b=c2d(b) |
b= right(@.col.row, 1) ; b= c2d(b) /* " " " blue " " */ |
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_= d2c( (.2126*r + .7152*g + .0722*b) % 1) /*convert RGB number ───► grayscale. */ |
_= d2c( (.2126*r + .7152*g + .0722*b) % 1) /*convert RGB number ───► grayscale. */ |
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@.col.row=copies(_, 3) |
@.col.row= copies(_, 3) /*redefine old RGB ───► grayscale. */ |
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end /*row*/ /* [↑] D2C convert decimal ───► char*/ |
end /*row*/ /* [↑] D2C convert decimal ───► char*/ |
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end /*col*/ /* [↑] x%1 is the same as TRUNC(x) */ |
end /*col*/ /* [↑] x%1 is the same as TRUNC(x) */ |
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/*stick a fork in it, we're all done. */</lang> |
/*stick a fork in it, we're all done. */</lang><br><br> |
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Other alternatives to express the ''blue'' color are: |
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<lang rexx> blue= "00 00 ff"x /*define the blue color (hexadecimal).*/ |
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blue= '00 00 FF'x /*define the blue color (hexadecimal).*/ |
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blue= '0000ff'x /*define the blue color (hexadecimal).*/ |
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blue= '00000000 00000000 11111111'b /*define the blue color (binary). */ |
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blue= '000000000000000011111111'b /*define the blue color (binary) */ |
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blue= 'zzy' /*define the blue color (character). */ |
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/*not recommended because of rendering.*/ |
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/*where Z is the character '00'x */ |
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/*where Y is the character 'ff'x */ |
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/*Both Z & Y are normally not viewable*/ |
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/*on most terminals (appear as blanks).*/</lang><br><br> |
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=={{header|Ruby}}== |
=={{header|Ruby}}== |
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