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diff --git a/upstream/debian-unstable/man1/ppmcie.1 b/upstream/debian-unstable/man1/ppmcie.1 new file mode 100644 index 00000000..2f0a9428 --- /dev/null +++ b/upstream/debian-unstable/man1/ppmcie.1 @@ -0,0 +1,372 @@ +\ +.\" This man page was generated by the Netpbm tool 'makeman' from HTML source. +.\" Do not hand-hack it! If you have bug fixes or improvements, please find +.\" the corresponding HTML page on the Netpbm website, generate a patch +.\" against that, and send it to the Netpbm maintainer. +.TH "Ppmcie User Manual" 1 "31 July 2005" "netpbm documentation" + +.SH NAME + +ppmcie - draw a CIE color chart as a PPM image + +.UN synopsis +.SH SYNOPSIS + +\fBppmcie\fP + +[ +\fB-rec709\fP|\fB-cie\fP|\fB-ebu\fP|\fB-hdtv\fP|\fB-ntsc\fP|\fB-smpte\fP +] +[\fB-xy\fP|\fB-upvp\fP] + +[\fB-red\fP \fIrx\fP \fIry\fP] + +[\fB-green\fP \fIgx\fP \fIgy\fP] + +[\fB-blue\fP \fIbx\fP \fIby\fP] + +[\fB-white\fP \fIwx\fP \fIwy\fP] + +[\fB-size\fP \fIedge\fP] + +[{\fB-xsize\fP|\fB-width\fP} \fIwidth\fP] + +[{\fB-ysize\fP|\fB-height\fP} \fIheight\fP] + +[\fB-noblack\fP] +[\fB-nowpoint\fP] +[\fB-nolabel\fP] +[\fB-noaxes\fP] +[\fB-full\fP] + +.UN description +.SH DESCRIPTION +.PP +This program is part of +.BR "Netpbm" (1)\c +\&. + +\fBppmcie\fP creates a PPM file containing a plot of the CIE +"tongue" color chart -- to the extent possible in a PPM +image. Alternatively, creates a pseudo-PPM image of the color tongue +using RGB values from a color system of your choice. +.PP +The CIE color tongue is an image of all the hues that can be described +by CIE X-Y chromaticity coordinates. They are arranged on a two +dimensional coordinate plane with the X chromaticity on the horizontal +axis and the Y chromaticity on the vertical scale. (You can choose +alternatively to use CIE u'-v' chromaticity coordinates, but the +general idea of the color tongue is the same). +.PP +Note that the PPM format specifies that the RGB values in the file are +from the ITU-R Recommendation BT.709 color system, gamma-corrected. +And positive. See +.BR "ppm" (1)\c +\& for details. If +you use one of the color system options on \fBppmcie\fP, what you get +is not a true PPM image, but is very similar. If you display such +\fBppmcie\fP output using a device that expects PPM input (which +includes just about any computer graphics display program), it will +display the wrong colors. +.PP +However, you may have a device that expects one of these variations on +PPM. +.PP +In every RGB color system you can specify, including the default +(which produces a true PPM image) there are hues in the color tongue +that can't be represented. For example, monochromatic blue-green with +a wavelength of 500nm cannot be represented in a PPM image. +.PP +For these hues, \fBppmcie\fP substitutes a similar hue as follows: +They are desaturated and rendered as the shade where the edge of the +Maxwell triangle intersects a line drawn from the requested shade to +the white point defined by the color system's white point. +Furthermore, unless you specify the \fB-full\fP option, \fBppmcie\fP +reduces their intensity by 25% compared to the true hues in the image. +.PP +\fBppmcie\fP draws and labels the CIE X-Y coordinate axes unless you +choose otherwise with options. +.PP +\fBppmcie\fP draws the Maxwell triangle for the color system in use +on the color tongue. The Maxwell triangle is the triangle whose +vertices are the primary illuminant hues for the color system. The +hues inside the triangle show the color gamut for the color system. +They are also the only ones that are correct for the CIE X-Y +chromaticity coordinates shown. (See explanation above). \fBppmcie\fP +denotes the Maxwell triangle by rendering it at full brightness, while +rendering the rest of the color tongue as 3/4 brightness. You can turn +this off with options. +.PP +\fBppmcie\fP also places a black cross at the color system's white +point (with the center of the cross open so you can actually see the +white color) and displays in text the CIE X-Y chromaticities of the +primary illuminants and white point for the color system. You can +turn this off with options, though. +.PP +\fBppmcie\fP annotates the periphery of the color tongue with the +wavelength, in nanometers of the monochromatic hues which appear +there. +.PP +\fBppmcie\fP displays the black body chromaticity curve for Planckian +radiators from 1000 to 30000 kelvins on the image. This curve traces the +colors of black bodies as various temperatures. +.PP +You can choose from several standard color systems, or specify one of +your own numerically. +.PP +CIE charts, by their very nature, contain a very large number of +colors. If you're encoding the chart for a color mapped device or +file format, you'll need to use \fBpnmquant\fP or \fBppmdither\fP to +reduce the number of colors in the image. + +.UN options +.SH OPTIONS +.PP +In addition to the options common to all programs based on libnetpbm +(most notably \fB-quiet\fP, see +.UR index.html#commonoptions + Common Options +.UE +\&), \fBppmcie\fP recognizes the following +command line options: +.PP +You may abbreviate any option to its shortest unique prefix. + + +.TP +\fB-rec709\fP +.TP +\fB-cie\fP +.TP +\fB-ebu\fP +.TP +\fB-hdtv\fP +.TP +\fB-ntsc\fP +.TP +\fB-smpte\fP +Select a standard color system whose gamut to plot. The default is +\fB-rec709\fP, which chooses ITU-R Recommendation BT.709, +gamma-corrected. This is the only color system for which +\fBppmcie\fP's output is a true PPM image. See explanation above. +\fB-ebu\fP chooses the primaries used in the PAL and SECAM +broadcasting standards. \fB-ntsc\fP chooses the primaries specified +by the NTSC broadcasting system (few modern monitors actually cover +this range). \fB-smpte\fP selects the primaries recommended by the +Society of Motion Picture and Television Engineers (SMPTE) in +standards RP-37 and RP-145, and \fB-hdtv\fP uses the much broader +\fIHDTV ideal\fP primaries. \fB-cie\fP chooses a color system that +has the largest possible gamut within the spectrum of the chart. This +is the same color system as you get with the \fB-cie\fP option to +John Walker's \fBcietoppm\fP program. + +.TP +\fB-xy\fP +plot CIE 1931 x y chromaticities. This is the default. + +.TP +\fB-upvp\fP +plot u' v' 1976 chromaticities rather than CIE 1931 x y +chromaticities. The advantage of u' v' coordinates is that equal +intervals of distance on the u' v' plane correspond roughly to the +eye's ability to discriminate colors. + +.TP +\fB-red\fP\fI rx ry\fP +specifies the CIE \fIx\fP and \fIy\fP co-ordinates of the red +illuminant of a custom color system and selects the custom system. + +.TP +\fB-green\fP\fI gx gy\fP +specifies the CIE \fIx\fP and \fIy\fP co-ordinates of the green +illuminant of the color system and selects the custom system. + +.TP +\fB-blue\fP\fI bx by\fP +specifies the CIE \fIx\fP and \fIy\fP co-ordinates of the blue +illuminant of the color system and selects the custom system. + +.TP +\fB-white\fP\fI wx wy\fP +specifies the CIE \fIx\fP and \fIy\fP co-ordinates of the white +point of the color system and selects the custom system. + +.TP +\fB-size\fP\fI edge\fP +Create an image of \fIedge\fP by \fIedge\fP pixels. The default is +512x512. + +.TP +\fB-xsize|-width\fP\fI width\fP +Sets the width of the generated image to \fIwidth\fP pixels. The +default width is 512 pixels. If the height and width of the image are +not the same, the CIE diagram will be stretched in the longer +dimension. + +.TP +\fB-ysize|-height\fP\fI height\fP +Sets the height of the generated image to \fIheight\fP pixels. The +default height is 512 pixels. If the height and width of the image +are not the same, the CIE diagram will be stretched in the longer +dimension. + +.TP +\fB-noblack\fP +Don't plot the black body chromaticity curve. + +.TP +\fB-nowpoint\fP +Don't plot the color system's white point. + +.TP +\fB-nolabel\fP +Omit the label. + +.TP +\fB-noaxes\fP +Don't plot axes. + +.TP +\fB-full\fP +Plot the entire CIE tongue in full brightness; don't dim the part +which is outside the gamut of the specified color system (i.e. outside +the Maxwell triangle). + + + +.UN interpretation +.SH INTERPRETATION OF COLOR CHART +.PP +A color spectrum is a linear combination of one or more monochromatic +colors. +.PP +A color is a set of color spectra that all look the same to the +human eye (and brain). Actually, for the purposes of the definition, +we assume the eye has infinite precision, so we can call two color +spectra different colors even though they're so close a person +couldn't possibly tell them apart. +.PP +The eye contains 3 kinds of color receptors (cones). Each has a +different response to the various monochromatic colors. One kind +responds most strongly to blue, another red, another green. Because +there are only three, many different color spectra will excite the +cones at exactly the same level, so the eye cannot tell them apart. +All such spectra that excite the cones in the same way are a single +color. +.PP +Each point in the color tongue represents a unique color. But +there are an infinite number of color spectra in the set that is that +color; i.e. an infinite number of color spectra that would look to you +like this point. A machine could tell them apart, but you could not. +.PP +Remember that the colors outside the highlighted triangle are +approximations of the real colors because the PPM format cannot +represent them (and your display device probably cannot display them). +That is, unless you're using a variation of PPM and a special display +device, as discussed earlier in this manual. +.PP +A color is always relative to some given maximum brightness. A +particular beam of light looks lime green if in a dim field, but +pea green if in a bright field. An image on a movie screen may +look pitch black because the projector is not shining any light on +it, but when you turn off the projector and look at the same spot in +room light, the screen looks quite white. The same light from that spot +hit your eye with the project on as with it off. +.PP +The chart shows two dimensions of color. The third is intensity. +All the colors in the chart have the same intensity. To get all +possible colors in the gamut, Make copies of the whole chart at every +intensity between zero and the maximum. +.PP +The edge of the tongue consists of all the monochromatic colors. +A monochromatic color is one with a single wavelength. I.e. a color +that is in a rainbow. The numbers you see are the wavelengths in +nanometers. +.PP +Any straight line segment within the tongue contains colors which +are linear combinations of two colors -- the colors at either end of +the line segment. +.PP +Any color in the chart can be created from two other colors (actually, +from any of an infinite number of pairs of other colors). +.PP +All the colors within a triangle inside the tongue can be created +from a linear combination of the colors at the vertices of that triangle. +.PP +Any color in the tongue can be created from at most 3 monochromatic +colors. +.PP +The highlighted triangle shows the colors that can be expressed +in the tristimulus color system you chose. (ITU-R BT.709 by default). +The corners of the triangle are the 3 primary illuminants in that +system (a certain red, green, and blue for BT.709). The edges of +the triangle, then, represent the colors you can represent with two +of the primary illuminants (saturated colors), and the interior colors +require all three primary illuminants (are not saturated). +.PP +In the ITU-R BT.709 color system (the default), the white point is +defined as D65, which is (and is named after) the color of a black +body at 6502 kelvins. Therefore, you should see the temperature curve +on the image pass through the white part of the image, and the cross +that marks the white point, at 6502 kelvins. +.PP +D65 white is supposed to be the color of the sun. If you have a +perfect BT.709 display device, you should see the color of the sun +at the white point cross. That's an important color, because when you +look at an object in sunlight, the color that reflects of the object +is based on the color of sunlight. Note that the sun produces a +particular color spectrum, but many other color spectra are the same +color, and display devices never use the actual color spectrum of the +sun. +.PP +The colors at the corners of the triangle have the chromaticities +phosphors in a monitor that uses the selected color system. Note +that in BT.709 they are very close to monochromatic red, green, +and blue, but not quite. That's why you can't display even one true +color of the rainbow on a video monitor. +.PP +Remember that the chart shows colors of constant intensity, +therefore the corners of the triangles are not the full colors of the +primary illuminants, but only their chromaticities. In fact, the +illuminants typically have different intensities. In BT.709, the +blue primary illuminant is far more intense than the green, which is +more intense than the red. Designers did this in order to make an +equal combination of red, green, and blue generate gray. I.e. a +combination of full strength red, full strength green, and full +strength blue BT.709 primary illuminants is D65 white. +.PP +The tongue has a sharp straight edge at the bottom because that's +the limit of human vision. There are colors below that line, but they +involve infrared and ultraviolet light, so you can't see them. This +line is called the "line of purples." + +.UN seealso +.SH SEE ALSO +.BR "ppmdither" (1)\c +\&, +.BR "pnmquant" (1)\c +\&, +.BR "ppm" (1)\c +\& + +.UN author +.SH AUTHOR +.PP +Copyright (C) 1995 by John Walker (\fIkelvin@fourmilab.ch\fP) +.PP +WWW home page: +.UR http://www.fourmilab.ch/ +http://www.fourmilab.ch/ +.UE +\& +.PP +Permission to use, copy, modify, and distribute this software and its +documentation for any purpose and without fee is hereby granted, +without any conditions or restrictions. This software is provided as +is without express or implied warranty. +.SH DOCUMENT SOURCE +This manual page was generated by the Netpbm tool 'makeman' from HTML +source. The master documentation is at +.IP +.B http://netpbm.sourceforge.net/doc/ppmcie.html +.PP
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