Measuring and testing – Specific gravity or density of liquid or solid
Reexamination Certificate
1998-12-21
2001-05-01
Oen, William (Department: 2855)
Measuring and testing
Specific gravity or density of liquid or solid
C399S074000
Reexamination Certificate
active
06223585
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to a laser imaging system and relates more particularly to the control of a laser imaging system using density patches on calibration films at the top of all other films.
BACKGROUND OF THE INVENTION
Medical laser printers have achieved wide acceptance in producing hard copy (film) of electronic (digital) images acquired from film digitizers, diagnostic imaging modalities (CT, MRI, PET, US), computed and direct digital radiography. Until recently, medical laser printers have produced medical image films which were processed using wet processing techniques. Medical laser printers have been introduced which produce medical image films which are dry processed through the use of heat. Control of the laser printer is aided by printing density patches on calibration and standard films. A densitometer reads the density patches to produce a control signal.
A problem arises in the accuracy of the densities read from the density patches by the densitometer.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a solution to the problems of the prior art.
According to a feature of the present invention, there is provided a method of determining the densities of film density patches comprising the steps of: providing a film having first, second and third density patches, respectively, having densities D
max
(maximum density), D
min
(mid density) and D
min
(minimum density); taking several density readings of each of the patches; and, either, estimating D
max
as the average of several measurements in the central portion of the first density patch, discarding at least one of the largest and smallest readings, estimating D
min
as a preselected value, or, searching the entire set of readings for the highest and lowest readings and using the highest reading as the estimated D
max
and the lowest reading as the estimated D
min
; and calculating D
mid
from the equation D
mid
=D
min
+a(D
max
−D
min
), where ais a constant with a value of less than one.
ADVANTAGEOUS EFFECT OF THE INVENTION
The present invention provides a method for accurately reading film density patches of medical image films produced by a medical laser printer.
REFERENCES:
patent: 5862433 (1999-01-01), Regelsberger et al.
Eastman Kodak Company
Noval William F.
Oen William
LandOfFree
Method of accurately measuring control film density regions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of accurately measuring control film density regions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of accurately measuring control film density regions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2568103