Warning: Wordy discussion of sprite graphic manipulation ahead.
I’m going to call this post “Scaling - The Silver Rule.” I realize that I’m 30 years too late for dozens of games that could have used this lesson, but it’s bugging me that I’m seeing this problem in games as late as 1991 and beyond, so there we are.
The silver rule is this: When you scale graphics, scale down as much as possible, and scale up as little as possible. It sounds simple enough, but an astonishing, distressing number of games take small sprites, detailed as they may be, and expand them using “Nearest Neighbor”-style algorithms to simulate a 3D approach motion. This results in a blocky, heavily pixelated image that detracts from the experience. Starting with a larger image and scaling down if needed will preserve detail and increase immersion.
Take these two graphic strips, for example. The top selection is from Namco’s Steel Gunner 2, released in 1991. The leftmost image here is the base sprite art for this enemy, taken from the game’s background memory. The game scales this small image upwards as necessary to show the enemy getting closer. The image furthest to the right is how that enemy appears at roughly the maximum scaling in game. Notice how jagged and blocky it appears. If it still doesn’t look too bad, remember that to get a feel for how poor this looks in-game, the image should be increased in size further until it covers a third of your screen.
The bottom selection is a mushroom from Sega’s Space Harrier, released six full years earlier in 1985, on a ROM board that stored one-fifth as much memory as Steel Gunner 2. I couldn’t determine the “base” size of this sprite from memory, but the fourth mushroom from the left is as large as it ever appears in game. I’ve scaled that image further in Photoshop until it matched approximately the size of the largest enemy in the top sequence, Because Sega uses a larger base image to start with, the mushroom is much more smooth and detailed, even at expansion beyond what was used in the game.
Why do I call this the silver rule? Because it’s not golden. There are times when it’s just fine to scale upwards, especially when it’s used in conjunction with other effects. There were some games on the SNES that combined upscaling and warping to make something appear to bounce forward and off the screen in a comical fashion. The bottom line is, if you’re looking to design a game, even if it has a “retro” feel, there’s no evidence to support scaling tiny sprites into big blocky images.
There, that’s off my chest. Now back to game overviews…