Views tracking with a fake image

What is better: png or gif?

[GreenLeaf]

In different code sources i saw 2 methods of tracking views (for example, newsletter open rate) with 'fake' image:

header("Content-Type: image/png");
print base64_decode('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAABGdBTUEAALGPC/xhBQAAAAZQTFRF////
AAAAVcLTfgAAAAF0Uk5TAEDm2GYAAAABYktHRACIBR1IAAAACXBIWXMAAAsSAAALEgHS3X78AAAAB3RJTUUH0gQCEx05cq
KA8gAAAApJREFUeJxjYAAAAAIAAUivpHEAAAAASUVORK5CYII=');

(without word wrap, of course)

and

Header("Content-Type: image/gif");
Header("Content-Length: 43");
echo chr(0x47).chr(0x49).chr(0x46).chr(0x38).chr(0x39).chr(0x61).chr(0x01).chr(0x00).
 chr(0x01).chr(0x00).chr(0x80).chr(0x00).chr(0x00).chr(0x04).chr(0x02).chr(0x04).
 chr(0x00).chr(0x00).chr(0x00).chr(0x21).chr(0xF9).chr(0x04).chr(0x01).chr(0x00).
 chr(0x00).chr(0x00).chr(0x00).chr(0x2C).chr(0x00).chr(0x00).chr(0x00).chr(0x00).
 chr(0x01).chr(0x00).chr(0x01).chr(0x00).chr(0x00).chr(0x02).chr(0x02).chr(0x44).
 chr(0x01).chr(0x00).chr(0x3B);

Which is better?
Thanks

[jatar_k]

I don't see why it would matter

[GreenLeaf]

Maybe there is some difference in gif/png support in various applications/browsers?

[jatar_k]

aahhh, missed that, sry, I would say gif

[GreenLeaf]

Thanks!

By the way, is that code in examples valid?

[jatar_k]

I imagine it works for what they are doing but you may need to customize it for what you are particularly doing.

[GreenLeaf]

Customize it? I thought that it was a code for 1x1 image's output. How it can be customized?
Thanks.

[jatar_k]

just try it, see if it works. :)

I haven't tried it

[GreenLeaf]

Thanks a lot for your answers!