Images.md

-By default, images have a width of 80% of the page column width. The aspect ratio is calculated from the size of the original image. Large images will be reduced in size, because of size limitations of images embedded directly in HTML.
+By default, images have a width of 80% of the page column width. The aspect ratio is calculated from the size of the original image. Large images will be reduced in size, because of size limitations of images embedded directly in HTML; for details see below.
 
-The `includegraphics` macro has a standard argument `scale`. If it is set **and is not equal to 1**, *laweb* writes size information to the HTML. A `scale` factor of 1.001 is a convenient value.
-
-This will cause the following conversion to XML to use the size information to format the image to the width given.
+The `includegraphics` macro has a standard argument `scale`. If it is set **and is not equal to 1**, *laweb* writes size information to the HTML. A `scale` factor of 1.001 is a convenient value. This will cause the following conversion to XML to use the size information to format the image to the width given.
 
 If you want to use the fixed size feature, it is your responsibility to scale the original image to reasonable sizes! Oversized images will probably not displayed correctly by all browsers. The standard display width in Pressbooks is about 720px, keep your size below this value.
 
-**Note**: the size written to HTML is off by a factor of 6.89. This will be fixed during XML conversion, so don't edit the sizes manually.
+**Note**: the size written to HTML is off by a factor of 6.89. This will be fixed during XML conversion, so don't edit the sizes manually.
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+
+# Detailed Size Control
+
+For a finer control, two macros are provided:
+
+Absolute scaling of images:
+```
+\graphicswidth[<width>][<url>]{<image>}
+```
+
+Relative scaling:
+```
+\graphicsscale[<scale>][<url>]{<image>}
+```
+
+The optional parameter `url` can be used in combination with the `--external-images` option in _laweb2pressbooks_, in case you want to host the images on a webserver. External images support SVG images, which are not supported for embedded images.