mass changes; fix titles; add examples; correct typos; clarifications;
unified style; etc.
diff --git a/Doc/libimageop.tex b/Doc/libimageop.tex
index 836ae76..4e15117 100644
--- a/Doc/libimageop.tex
+++ b/Doc/libimageop.tex
@@ -1,9 +1,9 @@
-\section{Built-in module \sectcode{imageop}}
+\section{Built-in Module \sectcode{imageop}}
\bimodindex{imageop}
The \code{imageop} module contains some useful operations on images.
It operates on images consisting of 8 or 32 bit pixels
-stored in Python strings. This is the same format as used
+stored in Python strings. This is the same format as used
by \code{gl.lrectwrite} and the \code{imgfile} module.
The module defines the following variables and functions:
@@ -17,49 +17,48 @@
\begin{funcdesc}{crop}{image\, psize\, width\, height\, x0\, y0\, x1\, y1}
-This function takes the image in \var{image}, which should by
+Return the selected part of \var{image}, which should by
\var{width} by \var{height} in size and consist of pixels of
-\var{psize} bytes, and returns the selected part of that image. \var{x0},
-\var{y0}, \var{x1} and \var{y1} are like the \code{lrectread}
-parameters, i.e. the boundary is included in the new image.
-The new boundaries need not be inside the picture. Pixels that fall
-outside the old image will have their value set to zero.
-If \var{x0} is bigger than \var{x1} the new image is mirrored. The
-same holds for the y coordinates.
+\var{psize} bytes. \var{x0}, \var{y0}, \var{x1} and \var{y1} are like
+the \code{lrectread} parameters, i.e.\ the boundary is included in the
+new image. The new boundaries need not be inside the picture. Pixels
+that fall outside the old image will have their value set to zero. If
+\var{x0} is bigger than \var{x1} the new image is mirrored. The same
+holds for the y coordinates.
\end{funcdesc}
\begin{funcdesc}{scale}{image\, psize\, width\, height\, newwidth\, newheight}
-This function returns an \var{image} scaled to size \var{newwidth} by
-\var{newheight}. No interpolation is done, scaling is done by
-simple-minded pixel duplication or removal. Therefore, computer-generated
-images or dithered images will not look nice after scaling.
+Return \var{image} scaled to size \var{newwidth} by \var{newheight}.
+No interpolation is done, scaling is done by simple-minded pixel
+duplication or removal. Therefore, computer-generated images or
+dithered images will not look nice after scaling.
\end{funcdesc}
\begin{funcdesc}{tovideo}{image\, psize\, width\, height}
-This function runs a vertical low-pass filter over an image. It does
-so by computing each destination pixel as the average of two
-vertically-aligned source pixels. The main use of this routine is to
-forestall excessive flicker if the image is displayed on a video
-device that uses interlacing, hence the name.
+Run a vertical low-pass filter over an image. It does so by computing
+each destination pixel as the average of two vertically-aligned source
+pixels. The main use of this routine is to forestall excessive
+flicker if the image is displayed on a video device that uses
+interlacing, hence the name.
\end{funcdesc}
\begin{funcdesc}{grey2mono}{image\, width\, height\, threshold}
-This function converts a 8-bit deep greyscale image to a 1-bit deep
-image by tresholding all the pixels. The resulting image is tightly
-packed and is probably only useful as an argument to \code{mono2grey}.
+Convert a 8-bit deep greyscale image to a 1-bit deep image by
+tresholding all the pixels. The resulting image is tightly packed and
+is probably only useful as an argument to \code{mono2grey}.
\end{funcdesc}
\begin{funcdesc}{dither2mono}{image\, width\, height}
-This function also converts an 8-bit greyscale image to a 1-bit
-monochrome image but it uses a (simple-minded) dithering algorithm.
+Convert an 8-bit greyscale image to a 1-bit monochrome image using a
+(simple-minded) dithering algorithm.
\end{funcdesc}
\begin{funcdesc}{mono2grey}{image\, width\, height\, p0\, p1}
-This function converts a 1-bit monochrome image to an 8 bit greyscale
-or color image. All pixels that are zero-valued on input get value
-\var{p0} on output and all one-value input pixels get value \var{p1}
-on output. To convert a monochrome black-and-white image to greyscale
-pass the values \code{0} and \code{255} respectively.
+Convert a 1-bit monochrome image to an 8 bit greyscale or color image.
+All pixels that are zero-valued on input get value \var{p0} on output
+and all one-value input pixels get value \var{p1} on output. To
+convert a monochrome black-and-white image to greyscale pass the
+values \code{0} and \code{255} respectively.
\end{funcdesc}
\begin{funcdesc}{grey2grey4}{image\, width\, height}
@@ -74,7 +73,7 @@
\begin{funcdesc}{dither2grey2}{image\, width\, height}
Convert an 8-bit greyscale image to a 2-bit greyscale image with
-dithering. As for \code{dither2mono}, the dithering algorithm is
+dithering. As for \code{dither2mono}, the dithering algorithm is
currently very simple.
\end{funcdesc}