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Diffstat (limited to 'pamrubber.html')
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diff --git a/pamrubber.html b/pamrubber.html index 1ebe15ba..30cce228 100644 --- a/pamrubber.html +++ b/pamrubber.html @@ -33,8 +33,8 @@ hyphens instead of single hyphen to denote options.</p> of <a href="http://netpbm.sourceforge.net/doc/index.html">Netpbm</a>.</p> <p>The <b>pamrubber</b> utility converts a pam image into a new image with the -contents moved around. The transformation is often called "rubber -sheeting": you identify control points (CP) on the source image and +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. <b>pamrubber</b> moves all the pixels around, stretching and compressing as necessary, as if the original image were on a sheet of rubber and you pulled on the sheet @@ -43,7 +43,7 @@ to make the control points move to their new locations. <p>The new image has the same dimensions and format as the original. <p>The transformation can happen in two very different ways, called -"quad" and "tri." With the former, you must specify four +"quad" and "tri." With the former, you must specify four control points (for both source and target). These are the corners of two quadrilaterals that will act as the coordinate system for both source and target images. Consider them as non-orthogonal (0,0), (0,1), (1,0) and (1,1) @@ -58,18 +58,18 @@ rectangle. When you specify only one control point, <b>pamrubber</b> uses a rectangle from the top left corner of the image to the single control point.</p> -<p>In "tri" mode, <b>pamrubber</b> conceptually cuts up the source +<p>In "tri" mode, <b>pamrubber</b> 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. -<p>When, in "tri" mode, you specify only a single control point in +<p>When, in "tri" mode, you specify only a single control point in the source and target image, <b>pamrubber</b> 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 +core of this utility in "tri" mode. Between the three edges of the central triangle and the four edges of the image, <b>pamrubber</b> constructs another seven triangles. Four control points define two central connected triangles. In total this results in cutting the source and target image up |