KR101026046B1 - Apparatus and method for correcting pixel defect of image sensor - Google Patents

Abstract

PURPOSE: An apparatus and a method for correcting pixel defect of an image sensor are provided to offer high quality preview image to a user by correcting 2x2 unit pixels. CONSTITUTION: An interface unit(131) receives an image signal which is outputted from an image sensor(12). The interface unit eliminates the first pixel row of the inputted image signal. A resize unit(132) resizes an image signal in which the first pixel row is eliminated. A defect correcting unit(133) corrects the defect by 1x2 unit pixels about the resized image.

Description

Apparatus and method for correcting pixel defects in an image sensor {APPARATUS AND METHOD FOR CORRECTING PIXEL DEFECT OF IMAGE SENSOR}

It relates to the field of image processing of the present invention, and more particularly, to a 2 × 2 4 pixel constituting a unit in an image sensor having 2 × 2 4 pixels as one unit sharing a single amplifier. The present invention relates to an apparatus and method for correcting pixel defects of an image sensor capable of generating a preview image by correcting defects in an image signal processor to which a correction algorithm in units of 1 × 2 pixels is applied at the same time.

In general, CMOS image sensors, which are widely applied to small camera modules, may have defects in which pixels do not detect accurate color values depending on physical properties and / or manufacturing processes.

In particular, the 5 million pixel CMOS image sensor, which is mainly used in mobile phones, is implemented in a structure in which four pixels included in one unit share one amplifier using four pixels of 2 × 2 as one unit. For example, defects frequently occur in four pixels of one unit.

On the other hand, the image signal processor (ISP) that adjusts the color, brightness and sharpness of the image signal input from the image sensor, processes the image of the high pixel input from the image sensor to enable the user to check the input image on the display unit It has the ability to generate low pixel images used for preview. As described above, when a defect occurs in the CMOS image sensor, the image signal processor includes an algorithm for correcting a defect occurring in the CMOS image sensor in the process of generating a low pixel image for preview.

However, in order to take advantage of the small size and relatively low throughput, a low-cost image signal processor, which is usually applied to a small camera module, does not have an algorithm for correcting a complex 2 × 2 pixel and can correct only 2 pixels of 1 × 2. You can have an algorithm. Considering the characteristics of the image sensor and the characteristics of the image signal processor, if a defect occurs in one unit pixel of 2 × 2 in the image sensor, the image signal processor may not completely remove the defect, and thus the pixel defect may Problems that are displayed as is may occur.

According to the present invention, when defects occur simultaneously in 4 pixels of 2x2 constituting one unit in an image sensor having 4 pixels of 2x2 sharing one amplifier as one unit, the present invention is performed in units of 1x2 pixels. An object of the present invention is to provide an apparatus and method for correcting pixel defects of an image sensor capable of generating a preview image by correcting defects in an image signal processor to which a correction algorithm is applied.

According to an aspect of the present invention,

An interface unit which receives an image signal output from an image sensor and erases the first pixel row of the received image signal;

A resizing unit for resizing the image signal from which the first pixel row is erased by alternately removing pixels from the image signal from which the first pixel row is erased in units of 4 pixels of 2x2; And

A defect correction unit for correcting a defect generated in units of 1 × 2 pixels with respect to the resized image

It provides a pixel defect correction apparatus of an image sensor comprising a.

In one embodiment of the present invention, the image sensor may be a CMOS image sensor including a plurality of pixel units consisting of 4 pixels of 2x2 sharing one amplifier.

In this embodiment, the image signal output from the image sensor may be an image signal in which defects occur simultaneously in 4 pixels of 2x2 sharing the single amplifier.

Further, in this embodiment, two pixels of 2x2 sharing the one amplifier have a first row of green and red pixels, a second row of blue and green pixels, and the first pixel. The green pixels of the row and the second row may be arranged diagonally.

As another means for solving the above technical problem, the present invention,

Receiving an image signal output from the image sensor;

Erasing the first pixel row of the input image signal;

Resizing the image signal from which the first pixel row is erased by alternately removing pixels from the image signal from which the first pixel row is erased in units of 4 pixels of 2 × 2; And

Correcting a defect occurring in units of 1 × 2 pixels for the resized image

It provides a pixel defect correction method of an image sensor comprising a.

According to the present invention, it is possible to easily correct defects in units of 2 × 2 pixels without providing a separate defect correction algorithm or applying a high-performance ISP to provide a user with a preview image of excellent quality.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiment of this invention is provided in order to demonstrate this invention more completely to the person skilled in the art to which this invention belongs. Therefore, it should be noted that the shape and size of the components shown in the drawings may be exaggerated for more clear explanation.

1 is a block diagram of a pixel defect correction apparatus of an image sensor according to an exemplary embodiment of the present invention.

As illustrated in FIG. 1, an apparatus for correcting pixel defects of an image sensor according to an exemplary embodiment of the present invention includes an interface unit 131 that receives an image input from the image sensor 12, and a resize of the input image. It may include a resizing unit 132 for performing a, and a defect correction unit 133 for performing a defect correction on the resized image. The interface unit 131, the resize unit 132, and the defect correction unit 133 may be implemented in an image signal processor (ISP) 13 of the camera module.

The interface unit 131 receives from the image sensor 12 an image signal obtained by electrically converting an image formed on the image plane of the image sensor 12 through the lens 11. A color filter forming a Bayer pattern is disposed on the image plane of the image sensor 12 so that each pixel of the image sensor 12 represents only one color of red-green-blue by the color filter. . The interface unit 131 receives an image signal formed in the Bayer pattern from the image sensor 12 and erases the first pixel row of the image signal. The interface unit 131 may interpolate an image signal having a Bayer pattern to form a color image in which each pixel includes both red-green-blue components.

The resize unit 132 resizes an image signal output from the interface unit 131 to form an image that can be displayed on a display for preview. The resize unit 132 may resize the image by alternately excluding two rows and two columns from each other. The image of the Bayer pattern is realized by repeating rows and columns of pixel units consisting of 4 pixels of 2 × 2. That is, a pixel unit composed of four pixels of 2 × 2 has a structure in which one row is composed of red and green pixels, the other row is composed of blue and green pixels, and the green pixels of two rows are arranged diagonally to each other. . The resizing of the image may be performed by alternately removing the pixel unit consisting of four pixels of 2 × 2 in the row direction and / or the column direction.

The defect correction unit 133 performs defect correction on a resized image in units of 1 × 2 pixels. The defect correction unit 133 applies an algorithm capable of correcting a defect occurring in units of 1 × 2 pixels, and the algorithm cannot correct a defect occurring in units of 2 × 2 pixels. According to the present invention, the ISP 13 having the defect correction unit 133 to which a defect that occurs in units of 1 × 2 pixels is applied has a defect that occurs in units of 2 × 2 pixels through resizing. By correcting to be a pixel-by-pixel defect, a defect correction algorithm in units of 1 × 2 pixels can be applied.

2 is a flowchart of a pixel defect correction method of an image sensor according to an exemplary embodiment of the present disclosure.

As shown in FIG. 2, in the method of correcting a pixel defect of an image sensor according to an exemplary embodiment of the present disclosure, a step (S21) of receiving an image signal output from an image sensor and a first pixel row of the received image signal are provided. Canceling (S22), and resizing the image signal from which the first pixel row is erased by alternately removing pixels in units of 4 pixels of 2x2 from the image signal from which the first pixel row is erased (S23); The method may include correcting a defect generated in units of 1 × 2 pixels with respect to the resized image (S24).

3 is a view showing an image change in accordance with the flow of the pixel defect correction method of the image sensor according to an embodiment of the present invention, the image change in accordance with the flow of the conventional pixel defect correction method for comparison with FIG. 4 is shown.

Hereinafter, the operation and effects of the present invention will be described in more detail with reference to the accompanying drawings.

First, when an image of a subject is imaged on the image plane (sensor surface) of the image sensor 12 through the lens 11, the image sensor 12 converts it into an electrical signal and outputs the converted signal. The image sensor 12 includes a plurality of pixels, and each pixel outputs light detected by the pixel as an electrical signal. As described above, a color filter is disposed on the sensor surface of the image sensor 12 such that each pixel detects only one color of red-green-blue, and thus the image signal output from the image sensor 12 is shown in FIG. As shown in 31 of 3, it becomes the form which has a Bayer pattern. Currently, a 5 million pixel CMOS image sensor is mainly used as the image sensor 12 in a camera module applied to a mobile phone. As shown in FIG. 3, such a CMOS image sensor may have a structure including a plurality of pixel units including 4 pixels of 2 × 2 sharing one amplifier. In such a CMOS image sensor, a defect occurs in a pixel unit consisting of 4 pixels of 2x2 sharing one amplifier. That is, all four pixels included in one pixel unit have a defect in not properly expressing colors. Defects generated in units of 2 × 2 pixels cannot be corrected by the defect correction unit 133 to which a defect correction algorithm of 1 × 2 pixels is applied.

Accordingly, in the present invention, after receiving the image signal from the image sensor 12 in the interface unit 131 (S21), the first row (C) of the input image signal as shown in 31 of FIG. Output an image signal such as (S22). That is, an image having a form in which columns are shifted one by one in the output signal of the image sensor 12 is input to the resize unit 132.

Subsequently, the resizing unit 132 alternately removes pixels by 2 × 2 pixels in the row and / or column direction of the image to generate a resized image as shown in FIG.

As illustrated in FIG. 3, the signal output from the image sensor 12 has a defect F1 in units of 2 × 2 pixels sharing one amplifier, but the first pixel row is erased by the interface unit 131. As a result, in the image output from the interface unit 131, the defects F11 may be separated into different 2 × 2 pixel units. That is, erasing of the first pixel row by the interface unit 131 causes defects F1 to be separated by 2 × 2 pixel units adjacent to each other, and then by 2 × 2 pixel units adjacent to each other by the resize by the resize unit 132. Since one of them is removed, only the defect F12 of 1 × 2 pixel unit remains in the image signal output from the resize unit 132.

Thus, in the defect correction unit 133 to which the algorithm of 1 × 2 pixel unit is applied, the defect of 1 × 2 pixel unit present in the resized image signal is corrected (S24), and the corrected image signal is transferred to the display 14. The output is previewed by the user (S25).

Referring to the conventional defect correction method shown in FIG. 4, the effects of the present invention will be more apparent. In the conventional defect correction method, when a defect F2 in units of 2 × 2 pixels exists in the output image signal of the image sensor shown in 41 of FIG. If the 2x2 pixel unit having a defect is not removed during the 2x2 pixel unit removal process at the resizing unit, the defect correction unit cannot correct the 2x2 pixel unit. This problem is displayed as it is.

In contrast, the present invention erases the first pixel row of the image output from the image sensor and causes the defect of 2 × 2 pixel unit to be changed to a defect of 1 × 2 pixel unit in the resizing process, thereby causing a defect of 1 × 2 pixel unit. The defect correction unit 133 to which the correction algorithm is applied may enable defect correction. As described above, the present invention can easily correct defects in units of 2x2 pixels without providing a separate defect correction algorithm or applying a high-performance ISP to provide a user with a preview image of excellent quality.

In the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the following claims and their equivalents.

1 is a block diagram of a pixel defect correction apparatus of an image sensor according to an exemplary embodiment of the present invention.

2 is a flowchart of a pixel defect correction method of an image sensor according to an exemplary embodiment of the present disclosure.

3 is a diagram illustrating an image change according to a flow of a pixel defect correction method of an image sensor according to an exemplary embodiment of the present invention.

4 is a diagram illustrating an image change according to the flow of a pixel defect correction method of a conventional image sensor.

* Description of the symbols for the main parts of the drawings *

11: lens 12: image sensor

13: image signal processor (ISP) 131: interface unit

132: resize unit 133: defect correction unit

14: display

Claims (8)

An interface unit which receives an image signal output from an image sensor and erases the first pixel row of the received image signal; A resizing unit for resizing the image signal from which the first pixel row is erased by alternately removing pixels from the image signal from which the first pixel row is erased in units of 4 pixels of 2x2; And A defect correction unit for correcting a defect generated in units of 1 × 2 pixels with respect to the resized image Pixel defect correction device of the image sensor comprising a. The method of claim 1, wherein the image sensor, An apparatus for correcting pixel defects of an image sensor, the CMOS image sensor comprising a plurality of pixel units each consisting of 4 pixels of 2x2 sharing one amplifier. The image signal output from the image sensor, And a defect occurs simultaneously in four pixels of 2x2 sharing the single amplifier. The method of claim 2, wherein the 2 × 2 4 pixels sharing the single amplifier are A pixel defect of an image sensor, wherein the first row is composed of green and red pixels, the second row is composed of blue and green pixels, and the green pixels of the first and second rows are arranged diagonally Correction device. Receiving an image signal output from the image sensor; Erasing the first pixel row of the input image signal; Resizing the image signal from which the first pixel row is erased by alternately removing pixels from the image signal from which the first pixel row is erased in units of 4 pixels of 2x2; And Correcting a defect occurring in units of 1 × 2 pixels for the resized image Pixel defect correction method of the image sensor comprising a. The method of claim 5, wherein the image sensor, A method for correcting a pixel defect of an image sensor, the method comprising: a CMOS image sensor including a plurality of pixel units consisting of 4 pixels of 2x2 sharing one amplifier. The method of claim 6, wherein the image signal output from the image sensor, And a defect occurs simultaneously in 4 pixels of 2x2 sharing the single amplifier. The method of claim 6, wherein the 2 × 2 4 pixels sharing the single amplifier are: A pixel defect of an image sensor, wherein the first row is composed of green and red pixels, the second row is composed of blue and green pixels, and the green pixels of the first and second rows are arranged diagonally Calibration method.

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