# ppmchange(1) - man - phpman > **TLDR:** Change all pixels of one color in a PPM image to another color. > - Exchange the first color in each `oldcolor` - `newcolor` pair with the second color: `ppmchange {{oldcolor1 newcolor1 oldcolor2 newcolor2 ...}} {{path/to/input.ppm}} > {{path/to/output.ppm}}` - Specify how similar colors must be in order to be considered the same: `ppmchange -closeness {{percentage}} {{oldcolor1 newcolor1 oldcolor2 newcolor2 ...}} {{path/to/input.ppm}} > {{path/to/output.ppm}}` - Replace all pixels not specified in the arguments by a color: `ppmchange {{-r|-remainder}} {{color}} {{oldcolor1 newcolor1 oldcolor2 newcolor2 ...}} {{path/to/input.ppm}} > {{path/to/output.ppm}}` *Source: tldr-pages* --- [ppmchange(1)](https://www.chedong.com/phpMan.php/man/ppmchange/1/markdown) General Commands Manual [ppmchange(1)](https://www.chedong.com/phpMan.php/man/ppmchange/1/markdown) ## NAME ppmchange - change all pixels of one color to another in a portable pixmap ## SYNOPSIS **ppmchange** [ **-closeness** _closeness_percent_ ] [ **-remainder** _remainder_color_ ] [ _oldcolor_ _newcolor_ ] ... [_ppmfile_] ## DESCRIPTION Reads a portable pixmap as input. Changes all pixels of _oldcolor_ to _newcolor_. You may spec‐ ify up to 256 oldcolor/newcolor pairs on the command line. **ppmchange** leaves all colors not mentioned unchanged, unless you specify the **-remainder** option, in which case they are all changed to the single specified color. You can specify that colors similar, but not identical, to the ones you specify get replaced by specifying a "closeness" factor. The colors can be specified in five ways: o A name, assuming that a pointer to an X11-style color names file was compiled in. o An X11-style hexadecimal specifier: rgb:r/g/b, where r g and b are each 1- to 4-digit hexadecimal numbers. o An X11-style decimal specifier: rgbi:r/g/b, where r g and b are floating point numbers between 0 and 1. o For backwards compatibility, an old-X11-style hexadecimal number: #rgb, #rrggbb, #rrrgggbbb, or #rrrrggggbbbb. o For backwards compatibility, a triplet of numbers separated by commas: r,g,b, where r g and b are floating point numbers between 0 and 1. (This style was added before MIT came up with the similar rgbi style.) If a pixel matches two different _oldcolor_s, **ppmchange** replaces it with the _newcolor_ of the leftmost specified one. ## OPTIONS ### -closeness _closeness_ is an integer per centage indicating how close to the color you specified a pixel must be to get replaced. By default, it is 0, which means the pixel must be the exact color you specified. A pixel gets replaced if the distance in color between it and the color you specified is less than or equal to _closeness_. The "distance" in color is defined as the cartesian sum of the individual differences in red, green, and blue intensities between the two pixels, normalized so that the difference between black and white is 100%. This is probably simpler than what you want most the time. You probably would like to change colors that have similar chrominance, regardless of their intensity. So if there's a red barn that is variously shadowed, you want the entire barn changed. But because the shadowing significantly changes the color according to **ppmchange**'s dis‐ tance formula, parts of the barn are probably about as distant in color from other parts of the barn as they are from green grass next to the barn. Maybe **ppmchange** will be enhanced some day to do chrominance analysis. ### -remainder **ppmchange** changes all pixels which are not of a color for which you specify an ex‐ plicit replacement color on the command line to color _color_. An example application of this is **ppmchange** **-remainder=black** **red** **red** to lift only the red portions from an image, or **ppmchange** **-remainder=black** **red** **white** **|** **ppmtopgm** to create a mask file for the red portions of the image. ## SEE ALSO [**pgmtoppm**(1)](https://www.chedong.com/phpMan.php/man/pgmtoppm/1/markdown), [**ppmcolormask**(1)](https://www.chedong.com/phpMan.php/man/ppmcolormask/1/markdown), [**ppm**(5)](https://www.chedong.com/phpMan.php/man/ppm/5/markdown) ## AUTHOR Wilson H. Bent. Jr. () with modifications by Alberto Accomazzi (‐ vard.edu) 07 January 2001 [ppmchange(1)](https://www.chedong.com/phpMan.php/man/ppmchange/1/markdown)