Appeal No. 2002-1646
Application No. 09/440,233
pixels having predetermined digital intensity values. A log-
transformed histogram, which is used to determine a threshold value
for the log-transformed image, is developed based on the input
value histogram. An upper limit value of the relevant portion of
the input data range is identified from the log-transformed
histogram based on the determined threshold value. With the lower
and upper limits of the useful portion of the input dynamic range
determined, the pixel values are scaled from the input dynamic
range to the second dynamic range.
Claim 1 is illustrative of the invention and reads as follows:
1. A method for converting digitized image pixel values from
a first range to a second range, the method comprising the steps
of:
(a) determining a lower limit value of a relevant portion of
the first range based upon non-log transformed pixel values;
(b) generating an intensity histogram representative of pixel
populations having specified intensities, and transforming the
histogram to generate a log-transformed histogram;
(c) identifying a threshold value for an upper limit of log-
transformed values from the log-transformed histogram;
(d) identifying a population of pixels having log-transformed
values having a desired relationship to the threshold value;
(e) determining an upper limit value of the relevant portion
of the first range based upon the identified population;
(f) converting the non-log transformed pixel values to
converted values; and
2
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