!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:

%%center
{{compression factor = original_volume / mdp_volume}}%%


;:* ''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.

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!2. Check [this page|http://msslxr.mssl.ucl.ac.uk:8080/eiswiki/images/dcgifs/new_EIS_dc_b.html] to see the corresponding __fits files__, __compression schemes__, __slit/sci.obj__, __original volume__, __mdp volume__ and __compression factor__.

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!3. Summary:

;:*__DPCM__ scheme testing has generated %%(color:#cc0000;)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 %%(color:#cc0000;)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 %%(color:#cc0000;)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 %%(color:#cc0000;)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
}}}