Dr. Mark Humphrys

School of Computing. Dublin City University.

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Displaying equations in HTML (using transparent gifs)

Like a lot of people, I write my mathematics in latex and then run latex2html to convert it to HTML for the web.

latex2html renders mathematics as inline images. We have 3 colors to think of - the mathematics, its background within the image, and the background of the window. Ideally, we would like black-on-X-on-X. One way of achieving this would be to have black-on-(transparent)-on-X. This is what latex2html does by default.

For various reasons, many of my pages use normal, solid, non-transparent, white gifs, and then a white background.

How to make non-transparent gifs (latex2html switch)


How to make non-transparent gifs (comment latex2html code)

I had some problems with the above switch, so here's an alternative. I noticed that latex2html generates normal gifs first and only then runs a routine to make them transparent. So I copied the latex2html file itself, edited the make_transparent routine, and commented out the relevant lines.

How to convert to other color (netpbm)

You can then convert these images to a color (non-transparent) other than white, and then give the pages that color background.

To use netpbm / pbmplus to convert the images:

for i in *.gif
 giftopnm $i | pnmdepth 255 | pgmtoppm "#ffffcc" | ppmtogif > tmp.gif
 mv tmp.gif $i

How to convert to other color (giftrans)

You can do the same conversion using giftrans:
 giftrans -g white="#ffffcc" $i > tmp.gif


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On the Internet since 1987.

Wikipedia: Sometimes I link to Wikipedia. I have written something In defence of Wikipedia. It is often a useful starting point but you cannot trust it. Linking to it is like linking to a Google search. A starting point, not a destination. I automatically highlight in red all links to Wikipedia and Google search and other possibly-unreliable user-generated content.