When you use the WP’s ‘upload’ there is code to resize the pictures according to rules for the data in the files.
No, when i look at my images, the pictures i upload keep their image size. I tested it with a RGB picture:
Image on my desktop:
212.41 KB (217509 Bytes)
Fullsize Image on WordPress:
212.41 KB (217509 Bytes)
Thumbnail:
147.38 KB (150917 Bytes)
So, it would be great if wordpress would keep the color pallete…