Rite Life 393, 394 manual Log E Curve, Selection and Use of Film

Variations in processor conditions are monitored on this step.

•Contrast Index: An indicator of the slope of the straight-line portion of the D-Log E Curve is called Contrast Index. Select the step closest to but not larger than 2.20D. Subtract from this step the step closest to but not lower then 0.45D. Contrast Index is used to monitor processor variations in conjunction with the Speed Index.

FIGURE 1. D-Log E Curve

Optical density versus relative log exposure for typical radiographic film.

SPEED INDEX	CONTRAST INDEX
BASE+FOG

Selection and Use of Film

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