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pnmtopng !!!pnmtopng NAME SYNOPSIS DESCRIPTION OPTIONS SEE ALSO NOTE BUGS AUTHORS ---- !!NAME pnmtopng - convert a portable anymap into a Portable Network Graphics file !!SYNOPSIS __pnmtopng__ [[-verbose] [[-downscale] [[-interlace] [[-alpha file] [[-transparent [[=]color] [[-background color] [[-gamma value] [[-hist] [[-chroma wx wy rx ry gx gy bx by] [[-phys x y unit] [[-text file] [[-ztxt file] [[-time [[yy]yy-mm-dd hh:mm:ss] [[-filter type] [[-compression level] [[-force] [[''pnmfile''] !!DESCRIPTION Reads a portable pixmap as input. Produces a Portable Network Graphics file as output. Color values in PNG files are either eight or sixteen bits wide, so ''pnmtopng'' will automatically scale colors to have a maxval of 255 or 65535. Grayscale files will be produced with bit depths 1, 2, 4, 8 or 16. An extra ''pnmdepth'' step is not necessary. !!OPTIONS __-verbose__ Display the format of the output file. __-downscale__ Enables scaling of maxvalues of more then 65535 to 16 bit. Since this means loss of image data, the step is not performed by default. __-interlace__ Creates an interlaced PNG file (Adam7). __-alpha file__ The alpha channel of pixel (or image) specifies the transparency of a pixel. To create this fourth pixel value a separate ''.pbm-'' or ''.pgm-file'' is needed. In this file black (0) stands for fully transparant and white (1) will become opaque. The sizes of both pbm/pgm/ppm-files must be the same. If the information contained in the alpha mask can also be represented as a transparency index, it will be used, since this should result in a smaller image file. __-transparent color__ __ppmtogif__ marks the specified color as transparent in the PNG image. You specify the color as in ppmmake(1).__E.g. red__ or __rgb:ff/00/0d__. If the color you specify is not present in the image, __pnmtopnm__ selects instead the color in the image that is closest to the one you specify. Closeness is measured as a cartesian distance between colors in RGB space. If multiple colors are equidistant, __pnmtopnm__ chooses one of them arbitrarily. However, if you prefix your color specification with __-transparent =red__ Only the exact color you specify will be transparent. If that color does not appear in the image, there will be no transparency. __pnmtopng__ issues an information message when this is the case. __-background color__ To create a background color chunck in the ''png-file,'' which can be used for subsequent alpha-channel or transparent-color conversions. See -transparent for format of color. __-gamma value__ Creates an gAMA chunk. By providing the gamma-value of the ''pnm-file'' the software that lateron will display the ''png-file'' will be able to do the necessary gamma-corrections. A good rule-of-thumb is that when the file is created by a software program (like a CAD-program or a ray-tracer) the value is probably 1.0. When the ''pnm-file'' looks good on a non-gamma corrected PC display (which has itself a gamma-value of 2.2 - 2.8), a value of 0.45 should be given. __-hist__ Use this parameter to create a chunk that specifies the frequency (or histogram) of the colors in the image. __-chroma white point X and Y, red X and Y, green X and Y, and blue X and Y__ To specify the white point and rgb values following the CIE-1931 spec. __-phys x y unit__ When your image should not be displayed with square but with rectangular pixels this option should be used to create a pHYS chunk. When the unit-value is 0 the x and y only gives the ratio of pixel width and height. When it is 1 the x and y specify the number of pixels per meter. __-text file__ Allows to include comments in the text-chunk of the ''png-file.'' The format of the text-file is as follows: when the first column does not contain a blank or a tab, the first word is considered to be the keyword. For keywords to contain spaces, enclose them in double-quotes. When the first character on a line is a blank or tab, the rest of the line is a new line of the current comment. Note that the initial spaces are not considered to be part of the comment line. Here is an example: ------------------------------------------- Title PNG-file Author your name Description how to include a text-chunk into a PNG file Software pnmtopng ------------------------------------------- __-ztxt file__ The same as -text, but now the text will be compressed. __-time yy-mm-dd hh:mm:ss or -time yyyy-mm-dd hh:mm:ss__ This option allows you to specify the (modification)time. The year parameter can be given as a two- or a four-digit value. __-filter type__ When the types of filters must be restricted you can specify here which filter you want to use. Allowed values are: 0 (none), 1 (sub), 2 (up), 3 (avg) and 4 (paeth). __-compression level__ To explicitly set the compression level of zlib use this parameter. Select a level between 0 for no compression (max speed) and 9 for maximum compression. __-force__ When set, -force limits the optimizations of pnmtopng. A png-file similar to the pnm-input is as much as possible enforced. For example no paletted files will be created and alpha-channel images will not be converted to images with a transparency chunck. All flags can be abbreviated to their shortest unique prefix. !!SEE ALSO pngtopnm(1), gif2png(1), pnmgamma(1), pnm(5) !!NOTE Instead of xxxtopnm|pnmtopng, a specific converter should be used, if available. E.g. ''gif2png'' (GIF conversion), etc. !!BUGS There could be an option to read the comment text from pnm comments instead of a separate file. The program could be much faster, with a bit of code optimizing. !!AUTHORS Copyright (C) 1995-1997 by Alexander Lehmann and Willem van Schaik. ----
3 pages link to
pnmtopng(1)
:
pngtopnm(1)
ppmcolormask(1)
Man1p
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