Originally Posted by buckduke
I've just purchased a Lumix FZ35 to replace my previous digital.
I set the camera to 12meg picture size and the jpeg quality to maximum. This is a 12 meg camera but the file size, according to PS, is 32 megs. That's huge for a jpeg and I don't understand how it can be so. Could someone please explain that to me?
As dwig mentioned, JPEG files are compressed, and file size will vary by content. When uncompressed for viewing, you will have 3 bytes per pixel being used in memory (one byte for red, one byte for green and one byte for blue). If you multiple 3 bytes by the number of megapixels, you will come up with the open file size (how much space it's taking up in memory after being decompressed by your image editor or viewer).
So, if your image is 12 Megapixels (12 Million Pixels) like you'd have with a resolution setting of 4000 x 3000 pixels (4000 x 3000 = 12 Million), you'll use 36 Million Bytes of memory (12 Million Pixels x 3 Bytes) when it's uncompressed by your image editor for viewing or editing.