Image analysis – Color image processing
Reexamination Certificate
1997-12-04
2001-05-01
Boudreau, Leo (Department: 2721)
Image analysis
Color image processing
C382S128000, C382S168000, C382S274000
Reexamination Certificate
active
06226398
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to printing and more specifically to printing image files obtained from medical diagnostic imaging systems.
2. Description of the Prior Art
The various modalities of medical diagnostic imaging systems, such as X-ray machines, ultrasound machines, CTs and MRIs, include one or more detectors for detecting image information produced by the interaction of the modality with the patient. These detectors typically include convertors for converting analog signals received thereby into digital signals that can be processed by a digital computer into an image file representative of the portion of the patient being imaged. The image files can be processed by the digital computer of the imaging system to produce on a monitor, such as a CRT, a visually perceptive image of the body part imaged by the imaging system. More specifically, the digital computer processes the digital signals from the detector into, among other things, luminescence values associated with each pixel of the image displayed on the monitor. Each pixel may also have associated therewith color and hue information.
It is common for an imaging system to process the received signals into a high resolution image which is provided to the monitor, preferably a high definition monitor which is capable of reproducing the high resolution image. In order to process these high resolution images, each pixel of the high resolution image may have associated therewith a luminescence value having 12 to 16 bits of resolution. The ability of the monitor to produce luminescence values having between 12 and 16 bits of resolution permits the imaging system to produce a high definition picture of the imaged portion of the patient.
While such high definition pictures are desirable, it is often desirable to produce hard copies of the imaged portion of the patient. In this respect, it is still common practice for X-ray machines to produce images on film based media. Limitations of film based media, however, include the use of hazardous chemicals for developing and the cost of replication, storage and retrieval of film based media. Hard copies of imaged portions of the patient may also be produced by providing image files to a printer having the same resolution as the luminescence values of the image file. Limitations of such a printer, however, is its cost and its relatively low availability with respect to more commonly available printers having lower resolution. While it is desirable to produce hard copies of diagnostic images from image files utilizing commonly available printers, the resolution of these printers for each luminescence value is typically limited to 8 bits. Hence, detail from the actual image is lost thereby limiting the usefulness of such hard copy images.
It is an object of the present invention to provide a printer which adaptively adjusts the scaling of its printer luminescence values to the luminescence values of a histogram containing one or more groups of image luminescence values containing the most diagnostically useful image information. It is an object of the present invention to provide a method for adaptively converting the scaling of printer luminescence values to image luminescence values containing more diagnostically useful image information.
SUMMARY OF THE INVENTION
Accordingly, we have invented a method of producing a hard copy of an electronic image. The method includes receiving a plurality of image luminescence values each corresponding to one of a color and a shade of gray of a pixel of an electronic image. A distribution of luminescence values is generated from the plurality of image luminescence values. The luminescence values in the distribution having less than a desired quantity of image luminescence values associated therewith are determined. A group of continuous luminescence values each having one of greater than and equal to the desired quantity of image luminescence values associated therewith are identified in the distribution. The distribution includes on each side of the group of continuous luminescence values a boundary of the distribution or one of the luminescence values having less than the desired quantity of image luminescence values associated therewith. The group of continuous luminescence values are scaled to obtain a plurality of printer luminescence values and each printer luminescence value is printed to obtain a hard copy of the electronic image represented thereby.
The method can also include the steps of identifying in the distribution a plurality of groups of continuous luminescence values that are separated from each other in the distribution by at least one luminescence value having less than the desired quantity of image luminescence values associated therewith. Each luminescence value of each group of continuous luminescence values has one of greater than and equal to the desired quantity of image luminescence values associated therewith. Two or more of the plurality of groups of continuous luminescence values and the luminescence values therebetween, having less than the desired quantity of image luminescence values associated therewith, are scaled to obtain a plurality of printer luminescence values. The two or more groups of continuous image luminescence values are preferably adjacent.
A first predetermined image luminescence value can be assigned to image luminescence values less than the scaled image luminescence values. A second predetermined image luminescence value can be assigned to image luminescence values greater than the scaled image luminescence values. Alternatively, piecewise linear or non-linear scaling can be utilized to scale the image luminescence values over the entire distribution of luminescence values.
We have also invented a printer for converting to a printed image an electronic image comprised of a plurality of image luminescence values. The printer includes a port for receiving a plurality of image luminescence values each corresponding to one of a color and a shade of gray of a pixel of an electronic image. A print controller is connected between the port and a print engine. The port provides the received plurality of image luminescence values to the print controller which forms a histogram of the distribution of the plurality of image luminescence values. The print controller determines the luminescence values of the histogram having less than a desired quantity of image luminescence values associated therewith. The print controller identifies from the histogram at least two adjacent groups of continuous luminescence values having therebetween at least one of the luminescence values having less than the desired quantity of image luminescence values associated therewith. Each luminescence value of each group has one of greater than and equal to the desired quantity of image luminescence values associated therewith. The print controller scales the identified at least two adjacent groups of continuous luminescence values and the luminescence values therebetween to obtain a plurality of printer luminescence values. The print controller causes the print engine to print each printer luminescence value to obtain a printed image corresponding to the electronic image.
The print controller can obtain from a background portion of the electronic image one or more image luminescence values. From the obtained image luminescence values a median image luminescence value can be determined and a predetermined image luminescence value can be assigned to image luminescence values below the median image luminescence value.
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O'Neill, Jr. Kevin J.
Varman Mahendra
Boudreau Leo
Minolta-QMS, Inc.
Sherali Ishrat
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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