Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Multiresolution image compression by two-stage application of JPEG progressive compression. (a) Original image 1,280 × 1,024 pixels. (b) Subsampled image (1/4) 320 × 256 pixels, first transmission. (c) Upsampled image 1,290 × 1,024 pixels. (d) Difference image (a)–(c) 1,280 × 1,024 pixels, second transmission (see the expanded Fig. 2d). (e) Last updated image 1,280 × 1,024 pixels.
