- You could also calculate which color is the most used color in the image, and make that the background color of the table. If 10% of the image have that color (for example white, in a logo) you could leave the class or id out of the table for these pixels.
- if two or more columns have the same color in a row, one could add a colspan. Since the word is rather long, it makes only sense from 2 columns onward, I guess, but if, say, the first 100 pixels of the image portrait a white line, instead of having 100 x '<td id='ff'></td>' you'd have <td id='ff' colspan=100></td'.
- The same could be done with column for colspan, albeit a bit more difficult.
- If there're certain pixel color patterns that appear throughout the image (say a white pixel next to a black pixel) one could create a css .before and .after rule for these, that defines the pattern for one td, making the 2. unnecessary.
There's probably more.