PDA

View Full Version : Downloads and Resolution Math


chuckinsocal
Jan-09-2009, 02:15 PM
Hi Gang,

I have an image that is 2250 x 1372 pixels which comes out to about 3 Mpx.

The low res version for downloads is 1 Mpx which is obviously 1/3 of the orginal 3 Mpx. So, my logic says that if I take a third of the original 2250 px and a third of the 1372 px, I come up with 750 x 457 px but that multiplies out to only 342,750 px, not 1 Mpx.

Can someone tell me where my logic is flawed? I'm usually pretty good at math problems but I must have lost some brain cells recently. I'm feeling pretty dumb here.

Thanks.

jfriend
Jan-09-2009, 05:04 PM
1/3 off both sides is 1/3 x 1/3 = 1/9.

To end up with 1/3, you take the sqare root of 3 off both sides which is ~1.73 so you'd want an image of 2270/1.73 and 1372/1.73 = 1312 x 793 which is indeed about 1 Mpx.

chuckinsocal
Jan-10-2009, 03:03 PM
Thanks John ... The brain cells I lost must have contained info about the square root function. I'll have to find somewhere else to store that stuff now.

Thanks again.