PAMSHADEDRELIEF(1)

💖 PAMSHADEDRELIEF 💖 — the Netpbm User Manual, section (1), General Commands Manual, bestie edition 🎀

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✨ NAME ✨

pamshadedrelief — generate a shaded relief image from an elevation map 🏔️

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🦋 SYNOPSIS 🦋

pamshadedrelief

[-gamma g]

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🌸 DESCRIPTION 🌸

Okay so first things first: this program is part of Netpbm(1). Family reunion energy. 🫶

pamshadedrelief creates a shaded relief image from an elevation map. And what even is a shaded relief image, you ask? It's a visual image of terrain, showing the terrain as if illuminated by oblique light and viewed from above, so that the brightness of each spot depends upon its slope. Literally the terrain going ✨glow up✨ based on how slanted it is. The most iconic example of a shaded relief image is a relief map of the Earth, which shows mountains and valleys. Mountains! Valleys! All of it, rendered.

The image pamshadedrelief creates is as if illuminated by a light source from the left. Left-side lighting, no cap. 💡

The output image is a PAM with tuple type GRAYSCALE.

The program pamcrater is a good thing to use to demonstrate the function of pamshadedrelief. It generates a terrain map of a cratered landscape. So you can be like:

$ pamcrater | pamshadedrelief | pamx

and just watch the whole thing pop off. 🔥

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💅 OPTIONS 💅

In addition to the options common to all programs based on libnetpbm (most notably -quiet, see Common Options), pamshadedrelief recognizes the following command line option:

• -gamma factor
• -g factor

Okay so these two are the same option, bestie, just spelled differently. The specified factor is used to gamma adjust the image in the same manner as performed by pnmgamma. The default value is 1.0, which results in a medium contrast image. Values larger than 1 lighten the image and reduce contrast, while values less than 1 darken the image, increasing contrast. So like, bigger number = brighter and flatter, smaller number = darker and punchier. That's the vibe check. 🌈

⚠️ Note that this is separate from the gamma correction that is part of the definition of the PAM GRAYSCALE format. The image pamshadedrelief generates is a genuine, gamma-corrected PAM GRAYSCALE image in any case. This option simply changes the contrast and may compensate for a display device that does not correctly render PAM GRAYSCALE images. Don't get it twisted — these are two different gammas. 😭

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🎀 DESIGN NOTES 🎀

Not me about to spill the tea on the design: the -gamma option isn't really necessary, since you can achieve the same effect by piping the output from pamshadedrelief through pnmgamma. So why does it exist?? Because pamshadedrelief performs an internal gamma map anyway in the process of rendering the elevation array into the PAM GRAYSCALE format — so there's no additional overhead in allowing an additional gamma adjustment. Free real estate. It's giving efficiency. 💅

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🔍 SEE ALSO 🔍

• ppmrelief(1)
• pnmgamma(1),
• pnmsmooth(1)
• pamcrater(1)
• pam(1),

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👑 AUTHOR 👑

pgmcrater, from which this is derived, was written by John Walker:

John Walker
Autodesk SA
Avenue des Champs-Montants 14b
CH-2074 MARIN
Suisse/Schweiz/Svizzera/Svizra/Switzerland
    Usenet:kelvin@Autodesk.com
    Fax:038/33 88 15
    Voice:038/33 76 33

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.

(Fr fr, that's the whole permission grant, quoted with love. 🫶)

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📜 HISTORY 📜

pgmcrater was split into pamshadedrelief and pamcrater in Netpbm 10.68 (September 2014). See the history section of the pamcrater manual for details. Glow-up era. ✨

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🧚 DOCUMENT SOURCE 🧚

This manual page was generated by the Netpbm tool makeman from HTML source. The master documentation is at

http://netpbm.sourceforge.net/doc/pamshadedrelief.html

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and that's the whole page, bestie — netpbm documentation, dated 26 July 2014, from the Pamshadedr...User Manual(1). slay, go make some shaded relief, ily, mwah 💖💅🎀