Search engine spiders don't read graphics. They read only text. When submitting your URL to engines, be sure to follow the directions carefully and supply the URL as they ask for it. Bottom line, if the info that you provide for your URL doesn't work, your site won't get spidered. So, no typos, no spaces, no missing bits.
Some search engines spider almost immediately.
Some can take weeks. Some like Yahoo, involve a human screening process Some search engines use other resources for material. Many email applications will read a URL as a hypertext link if the whole thing is there, making it easier to click through to it. Get reciprocal links on more heavily trafficked sites. Not only are people already going there and will have a better chance of finding your page, but those sites get spidered frequently.