well, if i'm on the right track here m8 i'm afraid you can't,
pictures of low quality/ones created to be a small size have a lower number of pixels and low level of picture clarity so as soon as you zoom in you lose all the detail, you can only really zoom into high quality pictures.

feel free to correct me tho peeps, he may be describing a different problem.

Yeah, with raster images (images made up of pixels), you can't really clean up the quality that much when zooming in..

You need to use Vector images (images made up of location points) to be able to really zoom in without losing quality.

It's just really not possible with raster images. You can get a LITTLE zoom to clean up, but not a lot.

Are these photos from a digital camera? Or something you've designed? or what?

I agree you can't zoom in without losing quality, but no one really explained why soooo:

Basically when photoshop, or any image editing program, gets the command to double the dimensions of the image, it takes every pixel and doubles it.

So basically you could have a red green, green red square:

RG
GR

And end up with a much larger square but same pattern:

RRGG
RRGG
GGRR
GGRR

I am sure most programs will actually take the mean color between the two bordering ones to make up the new pixel.

Yeah, photoshop does a pretty good of anti-aliasing and "filling in the gaps" when you enlarge an image to make it appear more of a smooth transition between the colours, rather than just large blocks (at least, it does in 24Bit), but you won't retain the clarity of the smaller image.

Yep photos are made up of square pixels and there is nothing you can do apart from get a bigger picture.

Obviously unlike photographs if a picture is made up of vectors then you can zoom in all you like cos they are instead made up of mathamatical points.