Predicting dc using ac coefficients for JPEG coding

Gopal Lakhani

doi:10.1117/1.2844508

1 February 2008 Predicting dc using ac coefficients for JPEG coding

Gopal Lakhani

Author Affiliations +

Optical Engineering, Vol. 47, Issue 2, 027004 (February 2008). https://doi.org/10.1117/1.2844508

Abstract

The JPEG baseline algorithm codes the dc of a block by giving its difference with the dc of the previous block. We propose to use ac coefficients for this purpose. Our method computes the difference of the sum of pixels of two boundary columns (or rows), one belonging to the current block and the other to a previous block, and then manipulates it in the direct cosine transform (DCT) domain so that the average of the coded differences for the whole image is near zero. Experimental results show that our method reduces the average JPEG dc residual by about 75% for images compressed at the default quality level. The reduction is even higher for unquantized DCT blocks.

©(2008) Society of Photo-Optical Instrumentation Engineers (SPIE)

Citation Download Citation

Gopal Lakhani "Predicting dc using ac coefficients for JPEG coding," Optical Engineering 47(2), 027004 (1 February 2008). https://doi.org/10.1117/1.2844508

Published: 1 February 2008

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

;

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE