Inconvenients
Yeah there has to be some ;¬)
Difficulty of application
Unfortunately, this technique doesn't apply very easily to any kind of image. For instance, if you use it with photographs, there is very little chance that you'll get any size reduction, since a photo barely ever features exactly repetitive areas. Nevertheless, you can still use the scrolling, as shows Pat McClellan, in this article on DOUG (sources available)
The tile based scrolling specs will be better used on images completely created from scratch, for the sole purpose of being used with this technique. Which leads us to the second inconvenient...
Difficulty of creation
To create a level map, you'd better do it "upside down", that is start with tiles, and create the image with them. You'd then still have to create the map, which can be rather tedious to do "by hand". You'll probably want to create a level editor for this purpose.
Once you've created such a tool, it becomes way easier to create such images at will.
Repetitive aspect of the tiles
From its own nature, the bitmap resulting of this manipulation often has a repetitive aspect, where one can very easily see the tiles, which can give an artificial appearance. It's not annoying for images of a space hangar, but it can be for a country landscape... And the less different tiles there are, the more this problem will be important, though it would allow the image to be very light.
There are different ways to remedy this problem, such as creating transition tiles, or by creating them in such a way that they can connect with many other tiles to create many varied areas while keeping a limited number of different tiles. But at any rate, this needs additionnal work and brainstorming... The thing is, the result and the advantages of this technique are well worth the price.
| page 1 : introduction |