1. From 2008-06-21 to 2008-06-26, EIS ran a series of studies to test compression schemes of DPCM, JPEG90, JPEG85 & JPEG75.#

The compression factor for each scheme during these tests have been calculated by using the following equation:

* orginal_volume: obtained from the definition files of EIS compression studies (ID: 288, 289, 290, 291, 53100 KB in this case).

* mdp_volume: extracted from EIS MDP status fits files.

2. Check this page to see the corresponding fits files, compression schemes, slit/sci.obj, original volume, mdp volume and compression factor.#

3. Summary:#

*DPCM scheme testing has generated 7 fits files, and the compression factors are as follows:

2.59747  2.58256  2.57117  2.60936  2.58829  2.66812  2.581

range: 2.57117 ~ 2.66812
choose: 2.58
currently in planning tool: DPCM: 2.19 (AR) + 0.2 (slit) = 2.39

JPEG90 has generated 8 fits files, and the compression factors are as follows:

3.50601  3.49550  3.39017  3.44851  3.64140  3.42182  3.52820  3.57641}}

range=: 3.39017 ~ 3.64140
choose: 3.50
currently in planning tool: DPCM: 3.80 (AR) + 0.1 (slit) = 3.90

JPEG85 has generated 26 fits files, and the compression factors are as follows:

4.13710 4.13043 4.03683 4.07790 4.00781 4.05085 4.08570 4.05598 4.04064 4.11058 4.16667 4.16261 4.15587 4.21321 4.20492 4.21044 4.14780 4.20492 4.09091 4.05598 4.29073 4.03556 4.09875 4.11850 4.13310 4.22570

range=: 4.00781 ~ 4.29073
choose: 4.05
currently in planning tool: DPCM: 4.51 (AR) + 0.2 (slit) = 4.71

JPEG75 has generated 7 fits files, and the compression factors are as follows:

5.20284 5.06117 5.08727 5.10549 5.11976 5.27127 5.07519

range=: 5.06117 ~ 5.27127
choose: 5.09
currently in planning tool: DPCM: 5.80 (AR) + 0.0 (slit) = 5.80