CN101883219B - Image correction method and image processing system using the method - Google Patents

Abstract

The present invention provides an image correction method and an image processing system using the method. An image correction method comprises: (a) sensing a target pixel of a sensing column of an effective pixel area of an image sensor to generate at least one target pixel value; (b) at the same time point as performing step (a), sensing at least one reference pixel of a shielded area of the image sensor to generate a correction value, wherein the reference pixel and the sensing column do not belong to the same column; and (c) correcting and outputting the target pixel value with reference to the correction value. By making the sensing column and the column where the reference pixel is located not on the same column, the system's applicability is increased. Moreover, the existing hardware architecture can be utilized without adding additional hardware costs.

Description

Image correction method and image processing system using the method

technical field

The present invention relates to an image correction method and an image processing system using the method, in particular to an image correction method that does not use pixels in the same column as reference pixels and an image processing system using the method.

Background technique

Generally speaking, an image sensor (such as a Charge-coupled Device, CCD) is provided in an image processing system to sense incident light from an object and convert the incident light into electric charges.

FIG. 1 illustrates an image sensor 100 in the prior art. As shown in FIG. 1 , the image sensor 100 includes a pixel array (pixel array) 101 and a column sensing circuit 103 . The pixel array 101 generally includes an effective pixel area 105 and an original shielding area 107 . And some image sensors further include a reference masking area 108 . The column sensing circuit 103 is used for sensing the pixels in the effective pixel area 105, and its sensing method is to sense all the pixels of a sensing column at a time, for example, sensing all the pixels in the column 109 or 100, and then one by one the sensed Pixel value output. The reference pixel areas (or called black pixel areas, black pixel) 111 and 112 are used to correct the sensed pixel values of the sensing column 109 or 100 . The reason is that each image may have background signal noise, so by sensing the pixel value of the reference masking area 108, the background signal noise can be obtained to obtain a correction value, and then the output pixel value is corrected with this correction value (For example: output after subtracting the correction value from the sensed pixel value of the sensing column 109 or 100).

However, such a mechanism can only use the same reference shadow area as the sensed column to correct the sensed column, which is relatively inflexible in circuit design.

Contents of the invention

An object of the present invention is to provide an image correction method and an image processing system using the method, which can use a masked area in a column different from a sensing column as a reference pixel area.

An embodiment of the present invention discloses an image correction method, including (a) sensing a target pixel in one sensing column of an effective pixel area of an image sensor to generate at least one target pixel value; (b) At the same point in time when step (a) is performed, sensing at least one reference pixel in a shaded area of the image sensor to generate a correction value, wherein the reference pixel and the sensing column do not belong to the same column; and (c) correcting the target pixel value with reference to the correction value.

Another embodiment of the present invention discloses an image processing system, which includes a pixel array, a column of sensors, and a computing unit. The pixel array has an effective pixel area with a plurality of sensing columns and a shielding area. The column sensor is used to sense the target pixel of one of the sensing columns to generate at least one target pixel value, and sense the shading at the same time point when sensing the one of the sensing columns at least one reference pixel of the region to generate a reference pixel value. Wherein the reference pixel and the sensing column do not belong to the same column. A calculation unit, generating the correction value according to the reference pixel value and correcting the target pixel value with reference to the correction value.

According to the above-mentioned embodiments, the sensing column and the column where the reference pixels are located may not be located on the same column, so as to increase the availability of the system. Moreover, the original hardware architecture can be used without adding additional hardware costs.

Description of drawings

FIG. 1 illustrates a conventional image sensor.

FIG. 2 is a schematic diagram of an image correction method according to a first embodiment of the present invention.

FIG. 3 is a flowchart of an image correction method according to a first embodiment of the present invention.

FIG. 4 is a schematic diagram of an image correction method according to a second embodiment of the present invention.

FIG. 5 is a flowchart of an image correction method according to a second embodiment of the present invention.

Reference number

200, 400 image sensors

201, 203, 205, 401, 405 sheltered areas

207, 209, 403, 407 sensing columns

211, 409 effective pixel area

221, 421 computing units

Detailed ways

Certain terms are used throughout the description and claims to refer to particular elements. It should be understood by those skilled in the art that hardware manufacturers may use different terms to refer to the same element. The "comprising" mentioned throughout the specification and subsequent claims is an open term, so it should be interpreted as "including but not limited to".

FIG. 2 is a schematic diagram of an image correction method according to a first embodiment of the present invention. In this example, a fixed shaded area is selected as the reference pixel area (such as the shaded areas 201 , 203 and 205 ), instead of the shaded area in the same column as the sensing columns 207 and 209 as the reference pixel area. The reason for adopting such a mechanism is that the background signal noise in the image is related to the time point. Therefore, as long as it is at the same point in time, no matter where the pixel is located, there will be the same background signal noise. Therefore, any fixed shaded area can be selected as the reference pixel area. This can increase the flexibility of system operation

The first embodiment of the present invention shown in FIG. 2 can be represented by the flowchart of the image correction method shown in FIG. 3 . FIG. 3 includes steps 301 , 303 and 305 . Step 301 senses target pixels of one sensing column (207 or 209) of an effective pixel area (211) of an image sensor (200) to generate at least one target pixel value. Step 303 is to sense at least one reference pixel in a shaded area (213) of the image sensor (200) at the same time when step 301 is executed, wherein the reference pixel and the target pixel do not belong to the same column. In this embodiment, step 303 is to sense a fixed area of the shadow area (213). Step 305 generates a correction value and corrects the target pixel value with reference to the correction value.

FIG. 4 is a schematic diagram of an image correction method according to a second embodiment of the present invention. In this example, the reference pixel area is not a fixed area, and the shielding areas 401 and 405 selected as the reference pixel area are located in one column less than the columns to be sensed 403 and 407 respectively. That is to say, if the sensing column 403 is the Nth column, then the corresponding shielding area 401 is the N-1th column, and if the sensing column 407 is the Mth column, then the corresponding shielding area 405 is the M-1th column . Under this mechanism, the disadvantage of the prior art that the reference pixel area must be in the same column as the sensing column can be improved. It should be noted that this embodiment is not limited to the difference between the column where the reference pixel area is located and the sensing column by one column, the column where the reference pixel area is located may be more than one column different from the sensing column, that is, the column where the reference pixel area is located and The sensing columns may have a specific relationship, and in this embodiment, the specific relationship is that the column where the reference pixel region is located differs from the sensing column by one column.

The second embodiment of the present invention shown in FIG. 4 can be represented by the flowchart of the image correction method shown in FIG. 5 . FIG. 5 includes steps 501 , 503 and 505 . Step 501 senses target pixels of one sensing column (403 or 407) of an effective pixel area (409) of an image sensor (400) to generate at least one target pixel value. Step 503 At the same time when step 501 is executed, at least one reference pixel of a masked area (411) of the image sensor (400) is sensed to generate a correction value, wherein the reference pixel and the target pixel do not belong to the same column . In this embodiment, step 503 senses at least one reference pixel in a specific area in the shielding region 411 that has a specific relationship with the columns sensed in step 501 . In one embodiment, the column where the specific area is located is the Nth column, and the column sensed in step 501 is the N+X column, where N and X are positive integers greater than or equal to 1, that is, the column where the specific area is located differ from the sensed column by one column or more). Step 505 generates a correction value according to the reference pixel, and corrects the target pixel value with reference to the correction value.

In the above embodiment, however, the average value of the pixel values of the reference pixels may be calculated as the correction value. Alternatively, after removing the maximum and minimum values of the reference pixel values, the average value of the pixel values of the remaining reference pixels can be calculated as the correction value. It should be noted that how to calculate the correction value according to the pixel value of the reference pixel is known to those skilled in the art, and is not limited to the above calculation method. And in the above embodiment, steps 305 and 505 can be performed by a computing unit, such as the computing unit 221 shown in FIG. 2 and the computing unit 421 shown in FIG. 4 . The calculation units 221 and 421 can be integrated in the column sensing circuits 220 and 420 , but can also be independent from the sensing circuits 220 and 420 .

According to the above-mentioned embodiments, the sensing column and the column where the reference pixels are located may not be located on the same column, so as to increase the availability of the system. Moreover, the original hardware architecture can be used without adding additional hardware costs.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the present invention.

Claims (8)

1. An image correction method, characterized in that it is used to correct an image sensed by an image sensor, the image sensor has a pixel array, and the pixel array includes an effective pixel area and a shielding area, wherein The effective pixel area includes at least one target pixel and the masked area includes at least one reference pixel, wherein each column of the pixel array includes at least one target pixel and at least one reference pixel, and the image correction method includes: (a) sensing at least one of the target pixels to generate at least one target pixel value; (b) sensing at least one reference pixel to generate a correction value at the same point in time when step (a) is performed, wherein the reference pixel and the target pixel sensed at the same time do not belong to the same column; and (c) correcting and outputting the target pixel value with reference to the correction value; Wherein when the step (a) and the step (b) are carried out, the reference pixel is located in the Nth column, and the target pixel sensed in the step (a) is located in the N+Xth column, wherein N is greater than or equal to a positive integer of 1, and the X is a positive integer greater than or equal to 1. 2. The image correction method according to claim 1, wherein the masking area has a plurality of areas, and the step (b) senses a fixed area of the areas of the masking area to The correction values are generated for the target pixels in different columns. 3. The image correction method according to claim 1, wherein the step (b) senses the pixel values of a plurality of reference pixels in the shaded area, and calculates the pixel value of the reference pixels The average value is used as the correction value. 4. The image correction method according to claim 3, wherein the method further comprises removing the maximum and minimum values of the reference pixel values, and then calculating the remaining pixel values of the reference pixels The average value is used as the correction value. 5. An image processing system, characterized in that the system comprises: A pixel array having: an effective pixel area having at least one target pixel; and a masking area, including at least one reference pixel; Each column of the pixel array includes at least one target pixel and at least one reference pixel; a row of sensors for sensing at least one target pixel to generate at least a target pixel value, and sensing at least one reference pixel to generate a reference pixel value at the same time point when sensing the target pixel, wherein The reference pixel and the target pixel sensed at the same time point do not belong to the same column, wherein when the column sensor senses the reference pixel and the target pixel at the same time point, the column where the reference pixel is located is the Nth column row, and the target pixel is surrounded by the N+Xth row, wherein N is a positive integer greater than or equal to 1, and X is a positive integer greater than or equal to 1; and A calculation unit generates a correction value according to the reference pixel value and corrects the target pixel value with reference to the correction value. 6. The image processing system as claimed in claim 5, wherein the shading area has multiple areas, and the column sensor senses the following of a fixed area of the areas of the shading area The correction value is generated. 7. The image processing system according to claim 5, wherein the calculation unit calculates an average value of pixel values of the reference pixels as the correction value. 8. The image processing system according to claim 7, wherein the calculation unit removes the maximum and minimum values of the reference pixel values, and then calculates the pixel values of the remaining reference pixels. The average value is used as the correction value.

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