HTML FAQ's
HTML FAQ's
If your images are inside a table, be sure to set the BORDER, CELLSPACING, and CELLPADDING attributes to 0. 
Extra space between images is often created by whitespace around the <IMG> tag in the markup. It is safe to use newlines inside a tag (between attributes), but not between two tags. For example, replace this:

<td ...>
<img src=... alt=...>
<img src=... alt=...>
</td>

with this:

<td ...><img src=... alt=...><img src=... alt=...></td>

According to the latest specifications, the two should be equivalent. However, common browsers do not comply with the specifications in this situation. 
Finally, extra space between images can appear in documents that trigger the "standards" rendering mode of Gecko-based browsers like Mozilla and Firefox.