Color correction method for filterless pixels

Abstract

A color correction method for filterless pixels is disclosed. In one embodiment, an image sensor having a pixel array includes a plurality of filterless pixels. Each pixel of the plurality of filterless pixels includes a blue light region, a green light region, and a red light region. Incoming light passes through the blue light region, the green light region, and the red light region in succession. Readout circuitry is configured to receive a color signal output comprising a blue region signal from the blue light region, a green region signal from the green light region, a red region signal from the red light region, and correct the color signal output with a correction algorithm comprising a blue light correction algorithm, a red light correction algorithm, and a green light correction algorithm. The method is configured to output a corrected color signal provided by the correction algorithm.

Description

Technical Field

[0001] This disclosure generally relates to the design of image sensors, and more particularly to a method for color correction of filterless pixels of an image sensor. Background Technology

[0002] Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, and in medical, automotive, and other applications. The technologies used to manufacture image sensors continue to advance rapidly. For example, the demand for higher image sensor resolution and lower power consumption has driven further miniaturization of image sensors and their integration into digital devices.

[0003] An image sensor operates in response to image light from an external scene that is incident on the sensor. The image sensor includes an array of pixels with photosensitive elements (e.g., photodiodes) that absorb a portion of the incident image light and generate a corresponding charge in response. The charge of an individual pixel can be measured as the output voltage of each photosensitive element. Generally, the output voltage varies with the intensity and duration of the incident light. The output voltage of the individual photosensitive elements is used to generate a digital image (i.e., image data) representing the external scene.

[0004] In some applications, image sensors include filterless pixels with regions for absorbing different wavelengths of light (e.g., blue, green, and red). It is argued that light color detection occurs at the depth where light absorption is at its maximum, and that a light detection scheme for filterless pixels implies complete absorption of blue light in the blue region, complete absorption of green light in the green region, and complete absorption of red light in the red region. In reality, however, in the blue region of a vertically stacked diode array, there is partial absorption of both green and red light; in the green region, there is absorption of both blue and red light; and in the red region, there is absorption of both green and blue light. Therefore, a light correction scheme is still needed to compensate for color contamination absorption at all three wavelengths of interest. Summary of the Invention

[0005] In one aspect, this disclosure relates to an image sensor comprising: a pixel array including: a plurality of filterless pixels, wherein each of the plurality of filterless pixels includes: a blue light region; a green light region; and a red light region, wherein incoming light passes sequentially through the blue light region, the green light region, and the red light region; and a readout circuitry configured to: receive a color signal output, the color signal output including: a blue region signal from the blue light region, a green region signal from the green light region, and a red region signal from the red light region; and to correct the color signal output using a correction algorithm, the correction algorithm including: a blue light correction algorithm configured to correct the blue region signal using a first amount of green light and a second amount of red light absorbed in the blue light region; a red light correction algorithm configured to correct the red region signal using a third amount of blue light and a fourth amount of green light absorbed in the red light region; and a green light correction algorithm configured to correct the green region signal using a fifth amount of blue light and a sixth amount of red light absorbed in the green light region; and to output a corrected color signal provided by the correction algorithm.

[0006] In another aspect, this disclosure relates to a method for color correction of an image sensor described above, comprising: receiving a color signal output, the color signal output including a blue region signal from a blue light region, a green region signal from a green light region, and a red region signal from a red light region; correcting the color signal output using the correction algorithm, comprising: correcting the blue region signal using the blue light correction algorithm by means of a first amount of green light and a second amount of red light absorbed in the blue light region; correcting the red region signal using the red light correction algorithm by means of a third amount of blue light and a fourth amount of green light absorbed in the red light region; and correcting the green region signal using the green light correction algorithm by means of a fifth amount of blue light and a sixth amount of red light absorbed in the green light region; and outputting the corrected color signal provided by the correction algorithm. Attached Figure Description

[0007] Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein, unless otherwise specified, reference numerals refer to similar parts.

[0008] Figure 1 This is an example image sensor based on the technology of the present invention.

[0009] Figure 2A This is an example cross-section of the pixels of a pixel array according to the present invention.

[0010] Figure 2B It is based on the technology of the present invention Figure 2A A close-up view of an example of a pixel circuit system.

[0011] Figure 3 This is an example representation of a pixel circuit according to the technology of the present invention.

[0012] Figure 4 This invention relates to a method for color correction of filterless pixels in an image sensor.

[0013] Several views throughout the figures correspond to reference characters indicating the respective components. Those skilled in the art will understand that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, to aid in understanding the various embodiments of the invention, the dimensions of some elements in the figures may be enlarged relative to other elements. Furthermore, common and well-known elements that are useful or necessary in commercially viable embodiments are generally not depicted to facilitate a less obstructed view of these various embodiments of the invention. Detailed Implementation

[0014] Image sensors are disclosed, and more specifically, a method for color correction of filterless pixels in an image sensor is disclosed. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. However, those skilled in the art will recognize that the techniques described herein can be practiced without one or more of the stated specific details or can be practiced using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring certain aspects.

[0015] Throughout this specification, references to "an example" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that example is included in at least one embodiment of the invention. Therefore, the appearance of the phrase "in an example" or "in an embodiment" in various places throughout this specification does not necessarily refer to the same example. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more examples.

[0016] For ease of description, spatial relative terms (e.g., “below,” “under,” “lower,” “below,” “above,” “upper,” etc.) are used to describe the relationship of one element or feature to another element(s), as illustrated in the figures. It should be understood that, in addition to the orientations depicted in the figures, the spatial relative terms are intended to cover different orientations of the device during use or operation. For example, if the device in the figures is rotated, an element described as being “below,” “below,” or “below” other elements or features will then be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “below” can encompass both the above and below orientations. The device may be oriented in other ways (rotated 90 degrees or otherwise) and the spatial relative descriptions used herein shall be interpreted accordingly. Furthermore, it should be understood that when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or one or more intervening layers may exist.

[0017] Based on the foregoing, it should be understood that although specific embodiments of the invention have been described herein for illustrative purposes, various modifications may be made without departing from this disclosure. Furthermore, while various advantages and features associated with specific embodiments have been described above in the context of those embodiments, other embodiments may also exhibit such advantages and / or features, and not all embodiments are required to exhibit such advantages and / or features to fall within the scope of this invention. In the case of described methods, the method may include more, fewer, or other steps. Additionally, the steps may be performed in any suitable order. Therefore, this disclosure may cover other embodiments not explicitly shown or described herein. In the context of this disclosure, the terms "about," "approximately," etc., mean + / - 5% of the stated value.

[0018] Several technical terms are used throughout this specification. These terms will be given their general meaning in the field of their respective domains, unless otherwise specifically defined herein or the context in which they are used will clearly imply otherwise. It should be noted that in this document, component names and symbols are used interchangeably (e.g., Si and silicon); however, they have the same meaning.

[0019] Briefly, embodiments of the present invention relate to image sensors and a method for color correction of filterless pixels in an image sensor. In some embodiments, each of a plurality of pixels in an image sensor includes a region for absorbing blue light, a region for absorbing green light, and a region for absorbing red light. Incoming light may pass sequentially through each of these regions to generate a blue light signal, a green light signal, and a red light signal, respectively. In some embodiments, a readout circuitry system is configured to receive these optical signals and correct them using a correction algorithm. The correction algorithm may include: a blue light correction algorithm configured to correct the blue region signal by absorbing a first amount of green light and a second amount of red light in the blue light region; a red light correction algorithm configured to correct the red region signal by absorbing a third amount of blue light and a fourth amount of green light in the red light region; and a green light correction algorithm configured to correct the green region signal by absorbing a fifth amount of blue light and a sixth amount of red light in the green light region.

[0020] Figure 1 This is an example image sensor 100 according to the technology of the present invention. Figure 1 The illustration depicts an example imaging system 100 according to an embodiment of the present disclosure. The imaging system 100 includes a pixel array 102, a control circuitry system 104, a readout circuitry system 106 (also referred to as a pixel circuitry system), and functional logic 110. In one example, the pixel array 102 is a two-dimensional (2D) array of photodiodes or image sensor pixels 112 (e.g., pixels P1, P2, ..., Pn). As illustrated, the photodiodes are arranged in rows (e.g., rows R1 to Ry) and columns (e.g., columns C1 to Cx). In operation, the photodiodes acquire image data of an external scene, which can then be used to reproduce 2D images of people, places, objects, etc. However, in other embodiments, the photodiodes may be arranged in a configuration other than rows and columns.

[0021] In one embodiment, after each pixel 112 in the pixel array 102 acquires its image charge, image data is read out by the readout circuitry system 106 via bit line 118 and then transmitted to functional logic 110. In various embodiments, the readout circuitry system 106 may include a signal amplifier, an analog-to-digital converter (ADC) circuitry, and a data transmission circuitry. Functional logic 110 may store image data or even manipulate the image data by applying post-image effects (e.g., cropping, rotation, red-eye removal, brightness adjustment, contrast adjustment, or others). In some embodiments, control circuitry system 104 and functional logic 110 may be combined into a single functional block to control the capture of the image by the pixels 112 and the readout of image data from the readout circuitry system 106. For example, functional logic 110 may be a digital processor. In one embodiment, the readout circuitry system 106 may read one line of image data at a time along the readout column lines (bit lines 118), or various other techniques (e.g., serial readout or simultaneous fully parallel readout of all pixels (not illustrated)) may be used to read the image data.

[0022] In one embodiment, control circuitry 104 is coupled to pixel array 102 to control the operation of a plurality of photodiodes in pixel array 102. For example, control circuitry 104 may generate a shutter signal for controlling image acquisition. In one embodiment, the shutter signal is a global shutter signal for simultaneously activating all pixels within pixel array 102 to simultaneously capture their respective image data during a single data acquisition window. In another embodiment, the shutter signal is a rolling shutter signal, such that pixels in each row, column, or group are sequentially activated during consecutive acquisition windows. In yet another embodiment, image acquisition is synchronized with illumination effects, such as a flash.

[0023] In one embodiment, the readout circuitry 106 includes an analog-to-digital converter (ADC) that converts analog image data received from the pixel array 102 into a digital representation. The digital representation of the image data can be provided to functional logic 110. In some embodiments, the data transmission circuitry 108 can receive the digital representation of the image data in parallel from the ADC and can provide the image data serially to functional logic 110.

[0024] In various embodiments, the imaging system 100 may be included in a digital camera, mobile phone, laptop computer, etc. Additionally, the imaging system 100 may be coupled to other hardware components, such as a processor (general purpose or other), memory elements, outputs (USB port, wireless transmitter, HDMI port, etc.), lighting devices / flash, electrical inputs (keyboard, touch display, tracking pad, mouse, microphone, etc.), and / or a display. These other hardware components can deliver instructions to the imaging system 100, retrieve image data from the imaging system 100, or manipulate image data supplied by the imaging system 100.

[0025] Figure 2A This is an example cross-section of a pixel in a pixel array 200 according to the present invention. In some embodiments, the pixel is a complementary metal-oxide-semiconductor (CMOS) pixel.

[0026] Pixel array 200 has a p+ type substrate 201. In some embodiments, p-type doped regions 202 may be epitaxially deposited on substrate 201. In some embodiments, p-type doped regions 202 may extend to the surface of the pixel array. Region 202 may include vertically stacked n-type doped regions 203, 204, and 205. In some embodiments, vertically stacked n-type doped regions 203, 204, and 205 may be formed by ion implantation between successive epitaxial growth steps. In some embodiments, vertically stacked n-type doped regions 203, 204, and 205 may be formed by other means. Various techniques are well known to those skilled in the art of modern silicon device fabrication and processing, and the description herein is not intended to be limiting. In some embodiments, n-type doped regions 203, 204, and 205 are only lightly doped, such that they are depleted during normal operation of the pixel.

[0027] Similarly, n+ doped vertical extensions (also referred to herein as “plugs”) 206, 207 and 208 can be formed by ion implantation between epitaxial growth steps and act as conductive connectors that enable biasing and collection of photogenerated electrons from the doped layers 203, 204 and 205 from the surface of the silicon substrate 201.

[0028] In some embodiments, plugs 206, 207, and 208 are contacted by metal regions 211, 212, and 213. In some embodiments, metal regions 211, 212, and 213 may be formed through holes in the silicon dioxide dielectric layer 210, or as multi-level interconnects across many types of dielectric layers. Various techniques are well known to those skilled in the art of modern silicon device fabrication, and the description herein is not intended to be limiting. Metal regions 211, 212, and 213 may be formed of a single metal (e.g., aluminum) or constitute a complex metallization system formed of various layers of titanium nitride, titanium, tungsten, aluminum, copper, etc. Metal regions 211, 212, and 213 are then interconnected with various circuit components via metal wiring.

[0029] To prevent parasitic surface channel conductivity and shorting of plugs 206, 207, and 208, p+ doped isolation regions (also referred to herein as "channel stops") 209A, 209B, 209C, and 209D are inserted between each of plugs 206, 207, and 208. In some embodiments, channel stops 209A, 209B, 209C, and 209D are positioned in a direction perpendicular to the plane of the drawing (…). Figure 2A (Not shown in the drawing) Completely surrounds each of the corresponding plugs 206, 207 and 208.

[0030] When driven to a sufficiently high voltage, the n-type doped regions 203, 204, and 205 may not form conductive electrodes for the detection node capacitor; instead, they form depletion-type potential wells. When charge is generated at various depths in region 202, it first diffuses vertically into one of the n-type doped regions 203, 204, and 205, and then laterally into the corresponding plugs 208, 207, and 206 within the n-type doped regions 203, 204, and 205.

[0031] In some embodiments, a filterless pixel includes a blue light region BR that extends from a vertical depth X1 to X2; a green light region GR that extends from X3 to X4; and a red light region RR that extends from X5 to X6. A conventional light detection scheme implies complete absorption of blue light in the region labeled X1 to X2 (i.e., the boundary of the region extending from X1 to X2), complete absorption of green light in the region labeled X3 to X4, and complete absorption of red light in the region labeled X5 to X6. It is argued that light color detection occurs at the depth where light absorption is at its maximum, and that a light detection scheme for a filterless pixel implies complete absorption of blue light in the region labeled X1 to X2, complete absorption of green light in the region labeled X3 to X4, and complete absorption of red light in the region labeled X5 to X6. In reality, the blue light region BR of the vertically stacked diodes exhibits partial absorption of both green and red light, while the green light region GR exhibits absorption of both blue and red light, and the red light region RR exhibits absorption of both green and blue light.

[0032] Therefore, the technology of the present invention further includes Figure 3 The output circuit system shown and described herein is designed to correct and compensate for color contamination absorption at all three wavelengths of interest (blue, green and red).

[0033] In some embodiments, the image sensor disclosed herein includes pixels in which the color of light (e.g., red, blue, and green) is separated by a penetration depth in the Si. That is, red, blue, and green regions that absorb red, blue, and green light, respectively, are separated by a penetration depth in the Si. In some embodiments, the pixels of the image circuit are FOVEON. TM Pixel.

[0034] Figure 2B Display and description in Figure 2A A close-up view of section 2B, which shows an example pixel circuit system.

[0035] Figure 2B It is based on the technology of the present invention Figure 2A A close-up view of an example pixel circuit system. The circuit may include a reset transistor 217 that connects a charge detection node 215 to a reference voltage terminal 219 when a suitable reset level is applied to gate 218. In some embodiments, the accumulation of photogenerated charge on node 215 results in a voltage charge buffered by transistor 216, the drain of which is connected to V. dd Bias terminal 220. The output signal then appears at node 221 and can be further processed as voltage or current when supplied to the rest of the sensor circuitry. Circuit ground 222 (e.g.) Figure 2A (As shown in the image) can be used with p+ type doped substrate 201 (such as...) Figure 2A (As shown in the diagram). For a single pixel sensing three colors, each color has circuitry including a reset transistor 217 and an amplifier transistor 216. Those skilled in the art will recognize that more complex circuitry can be connected to pixel 200.

[0036] When a reset voltage is applied to node 215 and the corresponding two remaining nodes (the circuits connected to plugs 206 and 207), the potential of these nodes is raised to the reference bias level V. rf When the doping level of layer 203 (and layers 204 and 205) is sufficiently high, the potential at node 215, the potential of plug 208 (and plugs 207 and 206), and the potential of layer 203 (and layers 204 and 205) are approximately the same. Layer 203 and plug 208, acting as buried reverse-biased diodes, serve as single electrodes of the junction capacitor. The capacitance of this structure is higher than the required capacitance of pixel 200 because the junction area surrounding layer 203 on all sides is large.

[0037] When node 215 is reset to a sufficiently high voltage, only the potential of node 215 and the corresponding plug 208 changes. During pixel reset, the potential of region 203 remains relatively constant and does not change significantly. Therefore, the capacitance of node 215 consists of the capacitance of plug 208 and the input capacitance of the circuit at node 215. This capacitance can be minimized through appropriate sizing of the transistors and structures, and furthermore, it is independent of the dimensions of regions 203, 204, and 205, and therefore independent of the pixel size. The reduced capacitance contributes to higher pixel sensitivity and lower noise.

[0038] Figure 3 This is an example representation of a pixel circuit according to the technology of the present invention. For pixels without filters (e.g.) Figures 2A to 2B Color correction is performed on the pixels shown in the diagram. In some embodiments, the pixel array 300 includes a readout circuitry system 106 configured to express a correction factor based on each color output signal and pixel parameters. In some embodiments, these pixel parameters may be obtained using computer-aided drafting techniques (TCAD) and / or measurement. In some embodiments, the correction factor is then subtracted from the color output outside the pixel in the circuitry.

[0039] In some embodiments, an image sensor comprising a pixel array is disclosed herein. The pixel array may comprise a plurality of filterless pixels. For simplicity, Figure 3 The diagram illustrates a single pixel. In some embodiments, each of a plurality of filterless pixels includes a blue light region BR, a green light region GR, and a red light region RR. In operation, incoming light L passes sequentially through the blue light region BR, the green light region GR, and the red light region RR. In some embodiments, the image sensor further includes a readout circuitry 106 configured to receive a color signal output, including receiving a blue region signal S from the blue light region BR. B Receive green region signal S from green light region GR G and receiving the red region signal S from the red light region RR. R .

[0040] In some embodiments, the readout circuitry system may also utilize a correction algorithm to correct the color signal output. The correction algorithm may include a blue light correction algorithm configured to correct the blue region signal S by absorbing a first amount of green light and a second amount of red light within the blue light region BR. B The red light correction algorithm is configured to correct the red region signal S by absorbing a third amount of blue light and a fourth amount of green light within the red region RR. R ; and a green light correction algorithm, which is configured to correct the green region signal S by absorbing a fifth amount of blue light and a sixth amount of red light within the green region GR. G .

[0041] The readout circuitry can be further configured to output the corrected color signal (S, respectively) provided by the correction algorithm. BCORR S GCORR and S RCORR In some embodiments, the readout circuitry system includes a specific analog circuitry system 301 configured to perform a correction algorithm.

[0042] The relationship between light penetration I and silicon (Si) depth is given by Equation 1.

[0043] I = I0e -αX

[0044] Equation 1

[0045] Here, I0 is the intensity of the irradiated light, α is the absorption coefficient, and X is the depth in Si, which in this pixel construction case is the depth from the front of the Si surface.

[0046] At any two points X1 and X2 (e.g. Figure 2A The calculation of the absorbed light between X1, X2, X3, X4 and X5 is shown in Equation 2.

[0047] I Absorbed =I0e -αX1 -I0e -αX2 =I0e -αX2 (e αX2-αX1 -1)

[0048] Equation 2

[0049] In some embodiments, the color signal outputs from the blue light region BR, the green light region GR, and the red light region RR are shown in Equations 3, 4, and 5, respectively.

[0050] S B =σ B I 0B e -αbX2 (e αbX2-αbX1 -1)+δ GR

[0051] Equation 3

[0052] S G =σ G I 0G e -αgX4 (e αgX4-αgX3 -1)+δ RB

[0053] Equation 4

[0054] S R =σR I 0R e -αrX6 (e αrX6-αrX5 -1)+δ BG

[0055] Equation 5

[0056] Where σ n (n = b, g, or r) are parameters for the conversion of absorbed light into a signal at a given wavelength. Furthermore, αb, αg, and αr are wavelength-specific absorption coefficients of b, g, and r, respectively. 0n (n = b, g, r) represents the light intensity at the chosen wavelength. σ n Combining quantum efficiency with charge-to-voltage conversion efficiency. B S G and S R These are the raw outputs from the blue region BR, the green region GR, and the red region RR, respectively. δ GR δ RB and δ BG The additional amount on the output is caused by crosstalk resulting from the absorption of green light-red light, red light-blue light, and blue light-green light outside their respective main absorption regions.

[0057] In some embodiments, the δ factor is negligible and can be ignored. In such embodiments, the correction algorithm is configured to consider δ... BG δ RB and δ GR δ is ignored when its combination is less than a predetermined threshold. BG δ RB δ GR Or a combination thereof. Furthermore, in such cases, the color signal output (S...) B S G S R The definitions of ) are shown in equations 6, 7 and 8 respectively.

[0058] S B =σ B I 0B e -αbX2 (e αbX2-αbX1 -1)→σ B I 0B =S B e αbX2 / (e αbX2-αbX1 -1)

[0059] Equation 6

[0060] S G =σ G I 0G e -αgX4 (e αgX4-αgX3-1)→σ G I 0G =S G e αgX4 / (e αgX4-αgX3 -1)

[0061] Equation 7

[0062] S R =σ R I 0R e -αrX6 (e αrX6-αrX5 -1)→σ R I 0R =S R e αrX6 / (e αrX6-αrX5 -1)

[0063] Equation 8

[0064] Therefore, in some embodiments, the calibrated light detection in the blue region (i.e., the blue light correction algorithm) is defined by equations 9a to 9c:

[0065]

[0066] =S B -[σ G I 0G e -αgX2 (e αgX2-αgX1 -1)+σ R I 0R e -αrX2 (e αrX2-αrX1 -1)]

[0067] Equation 9b

[0068]

[0069] Here, S B It is the raw output of the blue light region, S G It is the original output of the green light region, and S R It is the original output of the red light region.

[0070] Similarly, in some embodiments, the calibrated light detection in the green area (i.e., the green light correction algorithm) is determined by equation

[0071] Equations 10a to 10b are defined.

[0072]

[0073] In the above equation, S B It is the raw output of the blue light region, S G It is the original output of the green light region, and SR It is the original output of the red light region.

[0074] Similarly, in some embodiments, the calibrated light detection in the red region (i.e., the red light correction algorithm) is determined by equation

[0075] Equations 11a to 11b are defined.

[0076]

[0077]

[0078] In the above equation, S B It is the raw output of the blue light region, S G It is the original output of the green light region, and S R It is the original output of the red light region.

[0079] In some embodiments, the correction algorithm is performed in matrix form, as shown in Equation 12. In some embodiments, the correction algorithm includes digital processing.

[0080]

[0081] In some embodiments, equations 1 to 12 can be further defined by introducing a pixel-layout-based area factor.

[0082] Figure 4 This is a method 400 for color correction of filterless pixels of an image sensor according to the present invention. Method 400 can be performed by any of the image sensors disclosed herein, including image sensor 100, image sensor 200, and image sensor 300. In some embodiments, the image sensor includes a pixel array (e.g., pixel array 102) consisting of a plurality of pixels (e.g., pixel 103). In some embodiments, each of the plurality of pixels includes a red light region (e.g., red light region RR), a blue light region (e.g., blue light region BR), and a green light region (e.g., green light region GR). In some embodiments, incoming light (e.g., incoming light L) passes sequentially through the blue light region, the green light region, and the red light region.

[0083] In some embodiments, the image sensor further includes a readout circuitry system configured to perform a correction algorithm. The correction algorithm may include a red light correction algorithm, a blue light correction algorithm, and a green light correction algorithm.

[0084] In some embodiments, the image sensor further includes a control circuit system (e.g., control circuit system 104) and / or functional logic (e.g., functional logic 110).

[0085] In box 405, color signal output is received from the pixels of the pixel array. As used herein, "color signal output" includes red region signals (e.g., red region signal S). R ), blue area signal (e.g., blue area signal S) B ) and green area signals (e.g., green area signal S) G In some embodiments, the pixel is a filterless pixel. In some embodiments, the color signal output is generated based on incoming light illuminating the pixel and successively passing through the blue light region, the green light region, and the red light region.

[0086] In some embodiments, the blue area signal is defined as S B =σ B I 0B e -αbX2 (e αbX2-αbX1 –1)+δ GR The green area signal is defined as S. G =σ G I 0G e -αgX4 (e αgX4-αgX3 –1)+δ RB And the signal in the red area is defined as S. R =σ R I 0R e -αrX6 (e αrX6-αrX5 –1)+δ BG S B S G and S R These are the original outputs from the blue, green, and red regions, respectively. X1 to X2 define the blue region, X3 to X4 define the green region, and X5 to X6 define the red region. δ GR δ RB and δ BG These are the additional quantities to the original output caused by crosstalk between green and red light, red and blue light, and blue and green light, respectively. 0n (n = b, g, r) is the light intensity at the selected wavelength, σ n (n = b, g, r) are the parameters for converting absorbed light into a signal at a given wavelength, and αb, αg, and αr are the wavelength-specific absorption coefficients of b, g, and r, respectively.

[0087] In some embodiments, σ B I 0B =S B e αbX2 / (e αbX2-αbX1 –1). In some embodiments, σ G I 0G =SG e αgX4 / (e αgX4-αgX3 –1). In some embodiments, σ R I 0R =S R e αrX6 / (e αrX6-αrX5 –1).

[0088] In some embodiments, the correction algorithm is configured to consider δ BG δ RB and δ GR δ is ignored when its combination is less than a predetermined threshold. BG δ RB δ GR Or a combination thereof.

[0089] In block 410, a correction algorithm is used to correct the color signal output, as described herein. In some embodiments, the correction algorithm includes a red light correction algorithm, a blue light correction algorithm, and a green light correction algorithm.

[0090] In block 410a, a blue light correction algorithm is used to correct the blue region signal. In some embodiments, the blue light correction algorithm is configured to correct the blue region signal by absorbing a first amount of green light and a second amount of red light within the blue region. In some embodiments, the blue light correction algorithm is defined as S B –[σ G I 0G e -αgX2 (e αgX2-αgX1 –1)+σ R I 0R e -αrX2 (e αrX2-αrX1 –1)].

[0091] In block 410b, a red light correction algorithm is used to correct the signal in the red region. In some embodiments, the red light correction algorithm is configured to correct the signal in the red region by absorbing a third amount of blue light and a fourth amount of green light within the red region. In some embodiments, the red light correction algorithm is defined as S R –[S B e αbX2 e -αbX6 (e αbX6-αbX5 –1) / (e αbX2-αbX1 –1)+S G e αgX4 e -αgX6 (e αgX6-αgX5 –1) / (e αgX4-αrX3 –1)].

[0092] In block 410c, a green light correction algorithm is used to correct the green region signal. In some embodiments, the green light correction algorithm is configured to correct the green region signal by absorbing a fifth amount of blue light and a sixth amount of red light within the green region. In some embodiments, the green light correction algorithm is defined as S G –[S B e αbX2 e -αbX4 (e αbX4-αbX3 –1) / (e αbX2-αbX1 –1)+S R e αrX6 e -αrX4 (e αrX4-αrX3 –1) / (e αrX6-αrX5 –1)].

[0093] In some embodiments, boxes 410a, 410b, and 410c (collectively referred to as box 410) are performed as a matrix. In such embodiments, the correction algorithm is defined as:

[0094]

[0095] In box 415, a calibrated color signal is output based on a calibration algorithm. In some embodiments, the term "calibrated color signal" includes a calibrated red signal (e.g., a calibrated red signal). ), corrected blue signal (e.g., corrected blue signal) ) and corrected green signal (e.g., corrected green signal) ).

[0096] It should be understood that method 400 should be interpreted as representative only. In some embodiments, the process blocks of method 400 may be performed simultaneously, sequentially, in different orders, or even omitted without departing from the scope of this disclosure.

Claims

1. An image sensor, comprising: A pixel array, comprising: A plurality of filterless pixels, wherein each of the plurality of filterless pixels comprises: Blue light area; Green area; and The red light region, wherein the incoming light successively passes through the blue light region, the green light region, and the red light region, and The readout circuit system is configured as follows: Receive color signal output, the color signal output including: The blue region signal from the blue light region, Green area signal from the green light region, The red region signal from the red light region, and The color signal output is corrected using a correction algorithm, which includes: A blue light correction algorithm is configured to correct the blue region signal by absorbing a first amount of green light and a second amount of red light within the blue light region. A red light correction algorithm is configured to correct the red region signal by absorbing a third amount of blue light and a fourth amount of green light within the red light region. A green light correction algorithm is configured to correct the green region signal by absorbing a fifth amount of blue light and a sixth amount of red light within the green light region; and The output is the corrected color signal provided by the correction algorithm.

2. The image sensor according to claim 1, wherein the blue region signal is defined as S B =σ B I 0B e -αbX2 (e αbX2-αbX1 –1)+δ GR The green area signal is defined as S G =σ G I 0G e -αgX4 (e αgX4-αgX3 –1)+δ RB And the signal in the red region is defined as S R =σ R I 0R e -αrX6 (e αrX6-αrX5 –1)+δ BG , in: S B S G and S R These are the original outputs from the blue, green, and red regions, respectively. X1 to X2 define the boundary of the blue area. X3 to X4 define the boundary of the green area. X5 to X6 define the boundaries of the red area. δ GR δ RB and δ BG These are the additional amounts on the original output caused by crosstalk between green and red light, red and blue light, and blue and green light, respectively. I 0n (n = b, g, r) represents the light intensity at the chosen wavelength. σ n (n = b, g, r) are the parameters for converting absorbed light into a signal at a given wavelength, and αb, αg, and αr are wavelength-specific absorption coefficients of b, g, and r, respectively.

3. The image sensor according to claim 2, wherein σ B I 0B =S B e αbX2 / (e αbX2-αbX1 –1).

4. The image sensor according to claim 2, wherein σ G I 0G =S G e αgX4 / (e αgX4-αgX3 –1).

5. The image sensor according to claim 2, wherein σ R I 0R =S R e αrX6 / (e αrX6-αrX5 –1).

6. The image sensor of claim 2, wherein the correction algorithm is configured to... BG δ RB and δ GR δ is ignored when its combination is less than a predetermined threshold. BG δ RB δ GR Or a combination thereof.

7. The image sensor according to claim 2, wherein the blue light correction algorithm is defined as S B –[σ G I 0G e -αgX2 (e αgX2-αgX1 –1)+σ R I 0R e -αrX2 (e αrX2-αrX1 –1)].

8. The image sensor according to claim 2, wherein the green light correction algorithm is defined as S G –[S B e αbX2 e -αbX4 (e αbX4-αbX3 –1) / (e αbX2-αbX1 –1)+S R e αrX6 e -αrX4 (e αrX4-αrX3 –1) / (e αrX6-αrX5 –1)].

9. The image sensor according to claim 2, wherein the red light correction algorithm is defined as S R –[S B e αbX2 e -αbX6 (e αbX6-αbX5 –1) / (e αbX2-αbX1 –1)+S G e αgX4 e -αgX6 (e αgX6-αgX5 –1) / (e αgX4-αrX3 –1)].

10. The image sensor according to claim 2, wherein the correction algorithm is a matrix correction algorithm, such that:

11. A method for color correction of an image sensor according to claim 1, comprising: Receive the color signal output, the color signal output including the blue region signal from the blue light region, the green region signal from the green light region, and the red region signal from the red light region; The color signal output is corrected using the aforementioned correction algorithm, including: The blue light correction algorithm is used to correct the blue region signal by absorbing the first amount of green light and the second amount of red light within the blue light region. The red light correction algorithm is used to correct the signal in the red region by absorbing the third amount of blue light and the fourth amount of green light within the red light region. The green light correction algorithm is used to correct the signal in the green region by absorbing the fifth amount of blue light and the sixth amount of red light within the green light region; and The corrected color signal provided by the correction algorithm is output.

12. The method of claim 11, wherein the blue region signal is defined as S B =σ B I 0B e -αbX2 (e αbX2-αbX1 –1)+δ GR The green area signal is defined as S G =σ G I 0G e -αgX4 (e αgX4-αgX3 –1)+δ RB And the signal in the red region is defined as S R =σ R I 0R e -αrX6 (e αrX6-αrX5 –1)+δ BG , in: S B S G and S R These are the original outputs from the blue region, the green region, and the red region, respectively. X1 to X2 define the boundary of the blue area. X3 to X4 define the boundary of the green area. X5 to X6 define the boundaries of the red area. δ GR δ RB and δ BG These are the additional amounts on the original output caused by crosstalk between green and red light, red and blue light, and blue and green light, respectively. I 0n (n = b, g, r) represents the light intensity at the chosen wavelength. σ n (n = b, g, r) are the parameters for converting absorbed light into a signal at a given wavelength, and αb, αg, and αr are wavelength-specific absorption coefficients of b, g, and r, respectively.

13. The method of claim 12, wherein σ B I 0B =S B e αbX2 / (e αbX2-αbX1 –1).

14. The method of claim 12, wherein σ G I 0G =S G e αgX4 / (e αgX4-αgX3 –1).

15. The method of claim 12, wherein σ R I 0R =S R e αrX6 / (e αrX6-αrX5 –1).

16. The method of claim 12, wherein correcting the color signal output further includes δ BG δ RB δ GR δ is ignored when its combination is less than a predetermined threshold. BG δ RB δ GR Or a combination thereof.

17. The method of claim 12, wherein the blue light correction algorithm is defined as S B –[σ G I 0G e -αgX2 (e αgX2-αgX1 –1)+σ R I 0R e -αrX2 (e αrX2-αrX1 –1)].

18. The method of claim 12, wherein the green light correction algorithm is defined as S G –[S B e αbX2 e -αbX4 (e αbX4-αbX3 –1) / (e αbX2-αbX1 –1)+S R e αrX6 e -αrX4 (e αrX4-αrX3 –1) / (e αrX6-αrX5 –1)].

19. The method of claim 12, wherein the red light correction algorithm is defined as S Rcorr =S R –[S B e αbX2 e -αbX6 (e αbX6-αbX5 –1) / (e αbX2-αbX1 –1)+S G e αgX4 e -αgX6 (e αgX6-αgX5 –1) / (e αgX4-αrX3 –1)].

20. The method of claim 12, wherein the method further comprises using a correction matrix to correct the color signal output such that:

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