So basically, you want to reduce a sprite without the loss of quality inherent in doing so. In that case, it might be a good idea to hand-draw equivalent 8x8 sprites and use those.

In a game I'm currently making, I'm looking for an efficient algorithm to reduce a 16x16 sprite to 8x8 without just clustering every 4 pixels together because that looks like crap, It is in 4-level grayscale. does anyone have any help that they could give me for this?

Really the only * algorithm* is to take the group of 2x2 pixels and have the number of on pixels corresponding to the shade of grey in your image.  This probably is going to make some images blurry tho, so really the best way is to redraw them or ask one of the spriters around omni to redraw it

The game it's for is a zelda clone that I just started, and the screen is 8 by 10 sprites, so if the sprites were 8x8, it would fit perfectly on the calc, Ill post the sprites that I have right now, it's just for the outside though, if you want to try to convert them, be my guest, theres 247 of them. Im working on getting the inside ones.

http://i647.photobucket.com/albums/uu195/bryoda/zeldatiles.png?t=1292288380

May I direct you do this?

Hi Bryoda12 and welcome on the forums!

I tried to think about a way to shrink down 16x16 sprites by half without losing too much quality, for example, adding some anti-aliasing or something, but unfortunately I couldn't figure out a way to do it, not to mention it would still look weird. The only way to do it is to resize them on the computer and edit them by hand.

Or of course there are the sprites posted above (I swear there were other ones elsewhere too, though, although both seemed to look as great as each others)