Target detection for dot region alignment in optical storage systems using ink dots

• US 6,415,054 B1
• Filed: 07/10/1998
• Issued: 07/02/2002
• Est. Priority Date: 07/15/1997
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Walmsley, Simon Robert
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US09/113,051
• Time in Patent Office: 1,453 Days
• Field of Search: 382/232, 382/233, 382/181, 382/312-313, 382/317-324, 358/261.1, 358/453, 358/454, 358/474, 235/451, 235/455, 235/456, 235/458, 235/459, 235/461, 235/469
• US Class Current: 382/233
• CPC Class Codes: B41J 3/445 Printers integrated in other types of apparatus, e.g. printers integrated in cameras
• CPC Class Codes: H04N 1/32144 embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32352 Controlling detectability or arrangements to facilitate detection or retrieval of the embedded information, e.g. using markers for decoding, detection or retrieval operations H04N1/32149 and subgroups take precedence
• CPC Class Codes: H04N 5/2628 Alteration of picture size, shape, position or orientation, e.g. zooming, rotation, rolling, perspective, translation
• CPC Class Codes: H04N 5/772 the recording apparatus and the television camera being placed in the same enclosure
• CPC Class Codes: H04N 5/907 using static stores, e.g. storage tubes or semiconductor memories H04N5/91 takes precedence

Abstract

A method of rapidly decoding, in real time, sensed image data stored at a high pitch rate on a card. The method includes the steps of detecting the initial position of the image data, and decoding the image data so as to determine a corresponding bit pattern of the image data. Further, the step of decoding commences prior to completion of the step of detecting.

Claims

1. A method of decoding, in real time, data stored at a high pitch rate on a print media not withstanding rotations of said print media of up to substantially one degree, said print media comprising data printed in a data area, as a pattern of dots, said data area being at least preceded by a first predetermined number of targets each target printed as a pattern of dots having a plurality of rows and columns with each target offset a predetermined distance from the start of said data area and rotationally invariant under rotations of said print media, said method comprising the steps of:

sensing dots on said print media at a high pitch rate;

detecting an initial position of said data area by detecting the location of said targets, estimating a line substantially through at least a second predetermined number of said targets from positions located thereon and determining from said line and said location of targets said start of said data area;

sensing dots from said data area to form sensed data;

decoding the sensed data so as to determine a corresponding bit pattern of said data;

wherein said step of decoding commences prior to completion of said step of detecting.

2. A method as claimed in claim 1 wherein each of said targets comprise a small region of a first colour within a much larger region of a second colour distinguishable from said first colour.

3. A method as claimed in claim 2 wherein said small region comprises a single small dot and said larger region comprises a square region having said small region as its center.

4. A method as claimed in claim 1 wherein said method processes columns of sensed data at a time and transforms said columns into corresponding runlength encoded version of said columns.

5. A method as claimed in claim 4 wherein said runlength encoded versions are categorised into three categories of short, medium and long runlengths and said categories are utilized in determining the locations of said targets.

6. A method as claimed in claim 1 wherein said method goes to an error state if least than said second predetermined number of targets is found.