News Column

Patent Issued for Two-Dimensional Colored Projection Image from Three-Dimensional Image Data

September 10, 2014

By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Naidu, Ram (Newton, MA); Simanovsky, Sergey (Brookline, MA); Litvin, Andrew (Wakefield, MA), filed on July 31, 2009, was published online on August 26, 2014.

The assignee for this patent, patent number 8817019, is Analogic Corporation (Peabody, MA).

Reporters obtained the following quote from the background information supplied by the inventors: "The present application relates to the field of radiographic imaging. It finds particular application with computed tomography (CT) scanners. It also relates to medical, security, and other applications where generating a colored two-dimensional projection image from three-dimensional image data would be useful.

"CT and other radiographic imaging systems are useful to provide information, or images, of interior aspects of an object under examination. Generally, the object is exposed to radiation, and a two-dimensional image and/or a three-dimensional image is formed based upon the radiation absorbed by the interior aspects of the object, or rather an amount of radiation that is able to pass through the object. Typically, highly dense aspects of the object absorb more radiation than less dense aspects, and thus an aspect having a higher density, such as a bone or mass, for example, will be apparent when surrounded by less dense aspects, such as fat tissue or muscle.

"In three-dimensional imaging scanners, such as CT scanners, for example, three-dimensional colored images may be produced from data that is acquired from a radiological examination of an object. Generally, the colors are representative of a property of the object, or rather a property of interior aspects of the object, such as density and/or atomic number. For example, inside a suitcase under examination, a metal plate (e.g., with a density of 11340 kg/m.sup.3) may be colored red while a plastic box (e.g., with a density of 1000 kg/m.sup.3) may be colored yellow. A colored three-dimensional image may be projected onto an arbitrary observation plane through a technique commonly referred to as 'rendering.' The resulting colored image can be displayed on the computer screen. In an airport security environment, for example, coloring the image may assist security personnel in identifying objects that may be a threat (e.g. guns, knives, explosives, etc.).

"Three-dimensional image scanners may also display two-dimensional projection images of an object under examination. In some scanners, these two-dimensional images can be formed directly from the acquired data, without forming a 3D image. Because three-dimensional images take longer to generate and may be more time consuming for human personnel to review, in some applications (e.g., high throughput luggage examinations) it may be more beneficial for personnel to initially review a two-dimensional projection image. If the personnel believes a closer examination is warranted (e.g., a potential security threat exist in a piece of luggage), the personnel may consult a three-dimensional image of the object for a more detailed review of the object.

"While two-dimensional projection images have a high resolution and low artifacts (e.g., in comparison to two-dimensional synthetic images produced by rendering three-dimensional images, that typically comprise more artifacts and/or are more grainy), a disadvantage of two-dimensional projection images generated from three-dimensional image scanners is that they are often formed as grayscale images (e.g., the images lack color) because the image pixels carry information on a total attenuation value along a particular direction, and not on specific density values encountered along said direction. Thus, the interior aspects of the object will appear in varying shades of gray depending upon the aspects' attenuations.

"In some three-dimensional scanners, two-dimensional projection images may be colored similarly to projection images produced by two-dimensional scanners (e.g., line scanners). That is, the two-dimensional projection image may be colored based upon the attenuation of radiation that traversed the object under examination (e.g., a shade of gray on the projection image is replaced with a color indicative of the shade of gray it is replacing). For example, a first portion of the object attenuating fifty percent of the radiation that traversed the first portion may be colored blue on the projection image, and a second portion of the object, attenuating twenty percent of the radiation that traversed the second portion may be colored yellow on the projection image. While such coloring has proven useful, the coloring does not reliably depict the composition of aspects of the object under examination. For example, a stack of books may be colored the same color as a metal plate because both a stack of books and a metal plate may attenuate a similar amount of radiation. As can be appreciated, this can inhibit an ability to accurately examine one or more scanned objects."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "As provided herein a two-dimensional projection image can be colored similarly to a corresponding three-dimensional image. This can enhance on-screen visualization (e.g., to more easily identify threats) by allowing, for example, personnel to switch between the two-dimensional projection image and the three-dimensional image, and readily identify corresponding aspects of the two images. Additionally, the coloring may depict properties of the object, or aspects of the object, other than attenuation, such as density and/or atomic number for example. Thus, a metal plate may be colored differently than a stack of books, for example, so that such items can be readily differentiated from one another.

"Aspects of the present application address the above matters, and others. According to one aspect, a method for use with radiographic imaging is provided. The method comprises using three-dimensional image data of an object to generate a colored two-dimensional projection image of the object.

"According to another aspect, an apparatus is provided. The apparatus comprises a color generator configured to receive a two-dimensional projection image and a colored two-dimensional synthetic image that was rendered from three-dimensional image data. The color generator is also configured to color a first pixel of the projection image using color components of a first pixel of the colored synthetic image.

"According to yet another aspect, a method is provided. The method comprises generating a colored three-dimensional image of an object under examination and rendering a colored two-dimensional synthetic image of the object from the colored three-dimensional image. The method also comprises generating a two-dimensional projection image of the object, wherein the projection image is in correspondence with the colored synthetic image. The method further comprises extracting red-green-blue (RGB) components from a first pixel of the colored synthetic image and converting the RGB components to hue-saturation-value (HSV) components. The method also comprises computing at least one HSV component for a first pixel of the projection image using one or more HSV components for the first pixel of the colored synthetic image."

For more information, see this patent: Naidu, Ram; Simanovsky, Sergey; Litvin, Andrew. Two-Dimensional Colored Projection Image from Three-Dimensional Image Data. U.S. Patent Number 8817019, filed July 31, 2009, and published online on August 26, 2014. Patent URL:

Keywords for this news article include: Analogic Corporation.

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Source: Journal of Engineering

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