PAMRUBBER(1)

💖 PAMRUBBER 💖

okay bestie, this is the Pamrubber User Manual, section 1 of the General Commands Manual, and it's literally the glow-up your flat little images have been waiting for ✨

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🎀 NAME 🎀

pamrubber — a rubber-sheeting utility that stretches an image based on control points 🫶

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🌸 SYNOPSIS 🌸

pamrubber {-tri | -quad} [-linear] [-frame] [-randomseed=N] cp1x cp1y
[cp2x cp2y [cp3x cp3y [cp4x cp4y]]] cp1x cp1y [cp2x cp2y [cp3x cp3y
[cp4x cp4y]]] [filename]

Minimum unique abbreviation of options is acceptable. Yes queen, you can be lazy with your typing. And you may use double hyphens instead of single hyphen to denote options, no cap 💅

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🦋 DESCRIPTION 🦋

This program is part of Netpbm(1). Hi family 👑

The pamrubber utility converts a pam image into a whole new image with the contents moved around. The transformation is often called "rubber sheeting": you identify control points (CP) on the source image and specify new positions for those points in the new image. Then pamrubber moves all the pixels around, stretching and compressing as necessary — as if the original image were on a sheet of rubber and you literally pulled on the sheet to make the control points land in their new spots. it's giving arts and crafts but make it geometry 🍓

The new image has the same dimensions and format as the original. periodt.

The transformation can happen in two very different ways, called "quad" and "tri."

• With quad: you must specify four control points (for both source and target). These are the corners of two quadrilaterals that act as the coordinate system for both source and target images. Think of them as non-orthogonal (0,0), (0,1), (1,0) and (1,1) points. This transformation comes close to the one pamperspective does — however that program does other corrections as well 👀

When you specify less than four control points, the program adds control points for you, like a supportive bestie:

• With three control points, pamrubber chooses the fourth one such that the four points form a parallelogram.
• With two points, pamrubber considers them the opposite corners of a rectangle.
• When you specify only one control point, pamrubber uses a rectangle from the top left corner of the image to that single control point.

In "tri" mode, pamrubber conceptually cuts up the source and target image into triangles. It transforms within each corresponding pair of triangles in a stretching fashion. It's like pulling on the three corners of the triangle. In this mode, each pixel in the source image gets mapped to a position in the target image. No pixels are lost. we love a lossless moment 💖

When, in "tri" mode, you specify only a single control point in the source and target image, pamrubber creates four triangles from this point to the four corners of the image.

With two points, the program creates six triangles from the two endpoints of the line connecting the two points, again to the four corners of the image.

Three control points is, in a way, the core of this utility in "tri" mode. Between the three edges of the central triangle and the four edges of the image, pamrubber constructs another seven triangles.

Four control points define two central connected triangles. In total this results in cutting the source and target image up into ten triangles. iconic math fr fr 🔥

In this case, clearly a picture says more than a thousand words. There is a graphical illustration of these various modes at

www.schaik.com/netpbm/rubber

An example of how to use this type of rubber sheeting in cartography is in the article Visualizing the Landscape of Old-Time Tokyo 🗾

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✨ PARAMETERS ✨

The parameters are control points (cp) in pairs of x and y. The source and target image must have the same number of control points.

• The minimum number of values specified here is 4 — that's a single control point in the source and target image.
• The maximum is 16 — that's four control points in each image.

filename is the name of the input file. If you don't specify this, pamrubber reads the image from Standard Input. shy but flexible 🫶

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💅 OPTIONS 💅

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

• -tri | -quad — This selects the type of rubber sheeting done. You must specify exactly one of these options. not both. don't do it. pick a lane bestie 💀
• -linear — This determines whether pamrubber uses nearest neighbor interpolation or bilinear interpolation of four source pixels.
• -frame — This option causes pamrubber to overlay the target image with the edges of the quadrilaterals, respectively the triangles used for the rubber sheeting. To get the same overlay for the source image, use a pamrubber transformation with identical control points for source and target. cute little x-ray mode 🎀
• -randomseed=N — pamrubber randomizes some of its output. So that you can produce repeatable results, you can choose the seed of the random number generator with this option. If you use the same input image and the same random number generator seed, you should always get the exact same output. By default, pamrubber uses the time of day as the seed, so you get slightly different output when you run the program twice on the same input. (so random. very main character 🌈)
  • Before Netpbm 10.61 (December 2012), this was called -randseed, and that still works. vintage but valid 👑

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👑 SEE ALSO 👑

pam(1) and pamperspective(1)

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🌈 HISTORY 🌈

pamrubber was new in Netpbm 10.54 (March 2011). a 2011 baby, so it's basically a millennial but we still love it 💜

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🧚 AUTHORS 🧚

Willem van Schaik wrote this program in February 2011 and contributed it to Netpbm. legend behavior, honestly 🫶

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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/pamrubber.html

go read the real one if you want, but you already got the whole thing right here bestie, no gatekeeping in this house 💖

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okay that's the whole thing, every flag every triangle every number, we ate and left no crumbs 💅✨

netpbm documentation · February 2011 · Pamrubber User Manual(1) — mwah, see you in the man pages 🎀💜