Device and method for reading out an electronic image sensor that is subdivided into image points

• US 20020105584A1
• Filed: 10/29/2001
• Published: 08/08/2002
• Est. Priority Date: 10/31/2000
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Jung, Norbert, Eck, Kai
• Granted Patent: US 7,146,032 B2
• Time in Patent Office: Days
• US Class Current: 348/303
• CPC Class Codes: H04N 25/40 Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled
• CPC Class Codes: H04N 25/443 by reading pixels from selected 2D regions of the array, e.g. for windowing or digital zooming
• CPC Class Codes: H04N 25/7795 Circuitry for generating timing or clock signals
• CPC Class Codes: H04N 3/1562 for selective scanning, e.g. windowing, zooming

Abstract

The invention relates to a method for reading out the image points of a two-dimensional electronic image sensor, the image being subdivided into at least two different regions (2, 3) and the region of greater interest ROI (2) being read at a scanning rate which is higher than that used for the other region (3). Consequently, the region of interest (2) can be reproduced with a higher temporal resolution while making optimum use of the limited processing capacities. Preferably, the sensitivity of the reading unit is adapted in conformity with the scanning rate of a relevant image point so as to take into account the fact that image points that are read out less frequently collect a light intensity over a prolonged period of time and hence may reach high signal strengths. Regions that are less frequently read out can also be irradiated with a lower radiation intensity by applying appropriate masking. The method is very suitable for the imaging of time-critical processes in medical X-ray applications.

Claims

1. A method of reading out an electronic image sensor (1) that is subdivided into image points and wherefrom image points or groups of image points can be read out with a predetermined clock period,

characterized in that there are at least two quantities of image points and/or groups of image points whose elements are read out at a different scanning rate.

2. A method as claimed in claim 1,

characterized in that the image points are grouped so as to form lines of a two-dimensional image and that the lines that belong to a quantity are all read out at a uniform scanning rate.

3. A method as claimed in claim 2,

characterized in that the lines of image points of the image are alternately assigned to at least two quantities with different scanning rates.

4. A method as claimed in at least one of the claims 1 to 3,

characterized in that the quantities of image points and/or groups of image points overlap at least in a region of the image surface.

5. A method as claimed in at least one of the claims 1 to 4,

characterized in that the further processing of the signals from image points read out, notably their amplification, is performed in dependence on the relevant scanning rate of the image points.

6. A method as claimed in at least one of the claims 1 to 5,

characterized in that the image sensor is sensitive to X-rays.

7. A method as claimed in at least one of the claims 1 to 6,

characterized in that the image points and/or the groups of image points that are read out at a lower scanning rate are irradiated with a lower intensity.

9. A device as claimed in claim 8,

characterized in that it is arranged in such a manner that it is capable of carrying out a method as claimed in at least one of the claims 1 to 7.

8. A device for reading out an electronic image sensor (1) that is subdivided into image points and is provided with an addressing unit for selecting the image points and/or groups of image points to be read out within one clock period as well as with a reading unit for reading out the selected and addressed image points and/or groups of image points, characterized in that

the addressing unit is arranged in such a manner that it selects the addressable image points and/or groups of image points at a different scanning rate.

10. A device as claimed in claim 8 or 9,

characterized in that the reading unit is arranged in such a manner that it bases the processing, notably the signal amplification, on the scanning rate at which the relevant image points and/or groups of image points are addressed.