붙여 넣은 PNG가 JPG로 변환되는 이유는?

[codinghorror (Jeff Atwood)]

Pasted images typically come across as raw bitmaps, so saving them all as PNG (lossless) would be hugely wasteful in file size. Instead we test saving in both formats and see which results in a “reasonable” size, so (most) images end up efficiently stored as JPGs (lossy).