A cell image registration method and device

Abstract

The cell image registration method provided by the embodiment of the present invention includes: inverting the brightness of the background and target of the first bright field cell image to obtain a second bright field cell image, and using the first fluorescent cell image as the second fluorescent cell image; corroding the one with more pixels covered by the target in the second bright field cell image and the second fluorescent cell image to obtain a third bright field cell image and a third fluorescent cell image; and registering the first bright field cell image and the first fluorescent cell image according to the phase correlation method, the third bright field cell image and the third fluorescent cell image. The embodiment of the present invention first makes the directions of the relative brightness of the background and the target in the bright field cell image and the fluorescent cell image the same, and then corrodes one of the bright field cell image and the fluorescent cell image, and then uses the phase correlation method for registration after the two-step preprocessing, so that the corresponding target centroids in the bright field cell image and the fluorescent cell image are aligned, and the registration is more accurate and stable.

Description

Technical Field

[0001] The invention relates to the field of image processing, and in particular to a cell image registration method and a device thereof. Background Art

[0002] Cell counting is a commonly used function in biological research, and accurate counting results are very important for the evaluation of experiments. Currently, cell counting based on microscope cell images is one of the mainstream methods.

[0003] The captured cell images can be divided into bright field cell images and fluorescent cell images. When capturing bright field cell images, the bright field light source illuminates the cell fluid contained in the sample plate, and the light emitted by the bright field light source is received after being reflected or transmitted by all cells in the cell fluid, thereby obtaining a bright field cell image. When capturing fluorescent cell images, the fluorescent light source illuminates the cell fluid contained in the sample plate, and the light emitted by the fluorescent light source excites the fluorescent cells in the cell fluid. After the fluorescent cells are excited, the fluorescent signals emitted are received, thereby obtaining a fluorescent cell image. In addition to fluorescent cell images, bright field cell images are usually required for counting fluorescent cells, because bright field cell images contain richer cell texture features, which are conducive to the separation of aggregated cells and the distinction between cells and non-cellular substances. The method for counting fluorescent cells is as follows: first capture a bright field cell image and use the bright field cell image to circle the position of each cell, then switch the light source and camera parameters, capture a fluorescent cell image, and finally detect the strength of the fluorescent signal corresponding to the fluorescent cell image at the circled position of the bright field cell image to determine whether there are fluorescent cells. In actual applications, due to factors such as motor vibration and sample plate movement, the position of cells may change after taking a bright field cell image and then a fluorescent cell image, causing the fluorescent signal emitted by the fluorescent cell to deviate from its corresponding position in the bright field cell image or the fluorescent signal emitted by the fluorescent cell to enter the position of the non-fluorescent cell in the bright field cell image, etc. These will affect the accuracy of fluorescent cell counting.

[0004] For this, it is necessary to register and adjust the bright field cell image and the fluorescent cell image to align the two. Common registration methods include the corner method and the phase correlation method. Since the content of the cell image is single and the features are not obvious, the detector and descriptor of the corner method are not easy to define clearly, and the registration can easily fail. In the bright field cell image, the cell brightness is lower than the background, while in the fluorescent cell image, the fluorescent cell brightness is higher than the background; in addition, due to different light sources and camera parameters, the size of the fluorescent cell in the fluorescent cell image may be larger than its size in the bright field cell image, or it may be smaller. These differences will lead to the failure of registration when the phase correlation method is directly used for registration. Summary of the invention

[0005] The embodiment of the present invention provides a cell image registration method, aiming to solve the problem of accuracy and stability of registration of bright field cell images and fluorescent cell images in the prior art.

[0006] In a first aspect, a cell image registration method is provided, comprising:

[0007] acquiring a first bright field cell image and a first fluorescent cell image;

[0008] Inverting the brightness of the background and target of the first bright field cell image to obtain a second bright field cell image, and using the first fluorescent cell image as the second fluorescent cell image;

[0009] Performing corrosion processing on the second bright field cell image and the second fluorescent cell image, whichever has a larger number of pixels covered by the target, to obtain a third bright field cell image and a third fluorescent cell image;

[0010] The first bright field cell image and the first fluorescent cell image are registered according to the phase correlation method, the third bright field cell image and the third fluorescent cell image.

[0011] In a second aspect, a cell image registration device is provided, comprising:

[0012] An acquisition unit, used for acquiring a first bright field cell image and a first fluorescent cell image;

[0013] an inversion unit, used for inverting the brightness of the background and the target of the first bright field cell image to obtain a second bright field cell image, and using the first fluorescent cell image as the second fluorescent cell image;

[0014] an erosion unit, configured to perform an erosion process on the second bright field cell image and the second fluorescent cell image, whichever has a larger number of pixels covered by the target, to obtain a third bright field cell image and a third fluorescent cell image;

[0015] The registration unit is used to register the first bright field cell image and the first fluorescent cell image according to the phase correlation method, the third bright field cell image and the third fluorescent cell image.

[0016] In the embodiment of the present invention, before the bright field cell image and the fluorescent cell image are registered by the phase correlation method, the brightness of the background and the target of the bright field cell image are first reversed, so that the directions of the relative brightness of the background and the target in the bright field cell image and the fluorescent cell image are the same, which does not affect the phase spectrum of the bright field cell image and can avoid the possibility of failure of subsequent registration by the phase correlation method; then, the bright field cell image and the fluorescent cell image with a larger number of pixels covered by the target are corroded, so that the corresponding target size and shape in the bright field cell image and the fluorescent cell image are closer, and the phase spectra of the two still contain the contour information of the target centroid. After the two-step preprocessing, the phase correlation method is used for registration, and the corresponding target centroids in the bright field cell image and the fluorescent cell image are aligned, and the registration of the bright field cell image and the fluorescent cell image is more accurate and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0018] Figure 1 is a schematic diagram of a bright field cell image provided by Example 1 of the present invention;

[0019] Figure 2 is a schematic diagram of a fluorescent cell image provided by Example 1 of the present invention;

[0020] Figure 3 is a flow chart of a cell image registration method provided in Embodiment 1 of the present invention;

[0021] Figure 4 is a flow chart of performing registration by phase correlation method provided in the first embodiment of the present invention;

[0022] Figure 5 This is a diagram showing the effect of directly using the phase correlation method to perform registration according to the first embodiment of the present invention;

[0023] Figure 6 This is a diagram showing the effect of performing registration using the cell image registration method provided in the first embodiment of the present invention;

[0024] Figure 7 This is a structural block diagram of a cell image registration device provided in Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar modules or modules with the same or similar functions. The embodiments described below by reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limitations of the present invention. On the contrary, embodiments of the present invention include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0026] In practical applications, the cell brightness in the bright field cell image is lower than the background brightness and contains rich cell texture features; the fluorescent cell brightness in the fluorescent cell image is higher than the background brightness. Figure 1 Schematic diagram of a bright field cell image provided in Example 1 of the present invention. Figure 1 It is a bright field cell image taken with a black and white camera. The background is brighter and different parts of the cell show different grayscales, making it easier to distinguish the cell nucleus, cytoplasm, and cell boundaries. Figure 2 Schematic diagram of a fluorescent cell image provided in Example 1 of the present invention. Figure 2 This is a fluorescent cell image obtained by photographing the same cell fluid with a black and white camera and removing the background. The fluorescent cells are brighter and smaller. Although different parts of the fluorescent cells also show different grayscales, the fluorescent cells have significantly fewer texture features compared to the cells in the bright field cell image. If the above bright field cell image and fluorescent cell image are to be registered, a different image registration method from that used in ordinary life scenes is required.

[0027] In the embodiment of the present invention, before the bright field cell image and the fluorescent cell image are registered by the phase correlation method, the brightness of the background and the target of the bright field cell image are first reversed, so that the directions of the relative brightness of the background and the target in the bright field cell image and the fluorescent cell image are the same, which does not affect the phase spectrum of the bright field cell image and can avoid the possibility of failure of subsequent registration by the phase correlation method; then, the bright field cell image and the fluorescent cell image with a larger number of pixels covered by the target are corroded, so that the corresponding target size and shape in the bright field cell image and the fluorescent cell image are closer, and the phase spectra of the two still contain the contour information of the target centroid. After the two-step preprocessing, the phase correlation method is used for registration, and the corresponding target centroids in the bright field cell image and the fluorescent cell image are aligned, and the registration of the bright field cell image and the fluorescent cell image is more accurate and stable.

[0028] Figure 3 : is a flow chart of the cell image registration method provided by the first embodiment of the present invention. Figure 3 As shown, the method includes:

[0029] Step S301: Acquire a first bright field cell image and a first fluorescent cell image.

[0030] In an embodiment of the present invention, the first bright field cell image can be a grayscale image or a color image obtained by photographing the cell fluid contained in the sample plate, and then converting the color image into a grayscale image, a binary image, etc., or a local grayscale image or a local binary image after intercepting a local area from the above grayscale image or the binary image. The first fluorescent cell image can be a grayscale image or a color image obtained by photographing the same cell fluid contained in the sample plate, and then converting the color image into a grayscale image, a binary image, etc., or a local grayscale image or a local binary image after intercepting the corresponding local area from the above grayscale image or the binary image. Images of local areas are intercepted from corresponding positions for registration, such as intercepting a local area of ​​one quarter of the center of the image, which can speed up the calculation speed and avoid the influence of distortion or out-of-focus caused by the edge of the image.

[0031] Step S302: invert the brightness of the background and target of the first bright field cell image to obtain a second bright field cell image, and use the first fluorescent cell image as the second fluorescent cell image.

[0032] For the cell image, a preset threshold is selected according to the pixel value of the entire image to segment the background and the target, and the target is a cell, cell fragment or cell cluster, etc. In the first bright field cell image, the target is all the cells captured; in the first fluorescent cell image, the target is the fluorescent cells captured.

[0033] As an embodiment of the present invention, the brightness of the background and target of the first bright field cell image is inverted as follows: the pixel value of the pixel where the background of the first bright field cell image is located is set to 0, and the pixel value of the pixel where the target of the first bright field cell image is located is set to 255, so as to obtain a second bright field cell image. In the second bright field cell image, the cells are brighter and the background is darker. The first fluorescent cell image is used as the second fluorescent cell image. Optionally, the background of the first fluorescent cell image is processed to obtain the second fluorescent cell image as follows: the pixel value of the pixel where the background of the first fluorescent cell image is located is set to 0, that is, background removal processing is performed to obtain the second fluorescent cell image. In the second fluorescent cell image, the fluorescent cells are brighter and the background is darker. Therefore, in the second bright field cell image and the second fluorescent cell image, the relative brightness of the background and the target is in the same direction, that is, the difference between the background brightness and the target brightness has the same sign. From the principle of image processing, it can be seen that the phase spectrum of the image represents the information of the target contour, and the brightness inversion of the background and the target of the first bright field cell image will not affect the information of the target contour, that is, the phase spectrum of the first bright field cell image is the same as or not much different from the phase spectrum of the second bright field cell image. The background removal process of the first fluorescent cell image has little effect on its phase spectrum, that is, the phase spectrum of the first fluorescent cell image is the same as or slightly different from the phase spectrum of the second fluorescent cell image, which does not affect the calculation using the phase spectrum in the subsequent phase correlation method. At the same time, the subsequent phase correlation method is used for registration. Due to the characteristics of Fourier transform, fast Fourier transform, etc., the direction of the relative brightness of the background and the target in the two images to be registered is the same, which can avoid the possibility of registration failure.

[0034] Step S303: performing corrosion processing on the second bright field cell image and the second fluorescent cell image, whichever has a larger number of pixels covered by the target, to obtain a third bright field cell image and a third fluorescent cell image.

[0035] As an embodiment of the present invention, specifically: compare the number of pixels covered by the target in the second bright field cell image and the second fluorescent cell image; if the number of pixels covered by the target in the second bright field cell image is large, perform corrosion processing on the second bright field cell image; if the number of pixels covered by the target in the second fluorescent cell image is large, perform corrosion processing on the second fluorescent cell image.

[0036] In the embodiment of the present invention, the number of pixels with non-zero pixel values ​​in the second bright field cell image and the second fluorescent cell image are counted and compared. If the number of pixels covered by the target in the second bright field cell image is large, the second bright field cell image is corroded. Figure 1 The second bright field cell image is obtained by inverting the brightness of the background and target. Figure 2 Compared with the second fluorescent cell image, the number of pixels covered by cells in the second bright field cell image is larger. Figure 2If the number of pixels covered by the fluorescent cells in the image is small, the second bright field cell image is corroded to obtain a third bright field cell image, and the second fluorescent cell image is directly used as the third fluorescent cell image. If the opposite is true, the second fluorescent cell image is corroded to obtain a third fluorescent cell image, and the second bright field cell image is directly used as the third bright field cell image. The corroded process is iteratively performed until the iteration termination condition is met. The iteration termination condition can adopt the existing technology, which will not be repeated here.

[0037] The structural element of the corrosion process is a four-neighborhood template. The template is similar to the shape of the cell, so that the corrosion operation reduces the size of the target, but retains the center of mass of the target. In an embodiment of the present invention, after the corrosion process, the corresponding target size and shape in the third bright field cell image and the third fluorescent cell image are closer, which is conducive to subsequent image registration. At the same time, the phase spectra of the two still contain the contour information of the target center of mass. That is, the phase spectrum of the target center of mass is retained when the second bright field cell image is converted to the third bright field cell image, and the phase spectrum of the target center of mass is also retained when the second fluorescent cell image is converted to the third fluorescent cell image. Such a conversion does not affect the alignment of the corresponding target center of mass when the phase correlation method is used for subsequent registration.

[0038] Step S304: registering the first bright field cell image and the first fluorescent cell image according to the phase correlation method, the third bright field cell image and the third fluorescent cell image.

[0039] As an embodiment of the present invention, the process of performing registration by phase correlation method is as follows: Figure 4 As shown, the method includes:

[0040] Step S401: Calculate the cross power spectrum of the third bright field cell image and the third fluorescent cell image after Fourier transformation.

[0041] Step S402: performing inverse Fourier transform on the cross power spectrum to obtain the offset between the third bright field cell image and the third fluorescent cell image in the two-dimensional direction.

[0042] Step S403: registering the first bright field cell image and the first fluorescent cell image according to the offset in the two-dimensional direction.

[0043] In an embodiment of the present invention, during the conversion from the first bright field cell image to the second bright field cell image and the third bright field cell image, and during the conversion from the first fluorescent cell image to the second fluorescent cell image and the third fluorescent cell image, the third bright field cell image and the third fluorescent cell image retain the phase spectra of the target centroids in the first bright field cell image and the first fluorescent cell image, respectively. The offset of the third bright field cell image and the third fluorescent cell image in the two-dimensional direction calculated by the phase correlation method, that is, the offset of the target centroids of the two in the two-dimensional direction, is also the offset of the target centroids of the first bright field cell image and the first fluorescent cell image in the two-dimensional direction, which can be used for the registration of the first bright field cell image and the first fluorescent cell image, so that the corresponding target centroids in the first bright field cell image and the first fluorescent cell image are aligned. Preferably, fast Fourier transform is used instead of Fourier transform to improve computational efficiency.

[0044] Figure 5 is a diagram showing the effect of directly using the phase correlation method for registration according to the first embodiment of the present invention. Figure 1 and Figure 2 Perform registration. Figure 5 It can be seen that after registration, the fluorescent cells deviate significantly from their corresponding positions in the bright field cell image. Figure 6 is a diagram showing the effect of using the cell image registration method provided in the first embodiment of the present invention to register the cell image. Figure 1 and Figure 2 Perform registration. Figure 6 It can be seen that the overlap between the fluorescent cells and their corresponding positions in the bright field cell image is large, and the registration is more accurate.

[0045] The embodiment of the present invention performs two-step preprocessing on the bright field cell image and the fluorescent cell image before aligning the bright field cell image and the fluorescent cell image by the phase correlation method. The two-step preprocessing does not affect the contour information of the corresponding target centroid in the two images, and adjusts the image twice according to the characteristics of the phase correlation method, thereby reducing the possibility of failure of subsequent alignment using the phase correlation method and reducing the disadvantage of alignment caused by differences in size and shape after imaging the same cell due to different light sources and camera parameters. The two-step preprocessing combined with the phase correlation method is more accurate and stable than directly using the phase correlation method. For other alignment methods, such as the corner point method, the alignment relies on detectors and descriptors rather than phase spectra, and the effect obtained by combining the two-step preprocessing with the corner point method is far inferior to the effect obtained by combining the two-step preprocessing with the phase correlation method.

[0046] In the embodiment of the present invention, before the bright field cell image and the fluorescent cell image are registered by the phase correlation method, the brightness of the background and the target of the bright field cell image are first reversed, so that the directions of the relative brightness of the background and the target in the bright field cell image and the fluorescent cell image are the same, which does not affect the phase spectrum of the bright field cell image and can avoid the possibility of failure of subsequent registration by the phase correlation method; then, the bright field cell image and the fluorescent cell image with a larger number of pixels covered by the target are corroded, so that the corresponding target size and shape in the bright field cell image and the fluorescent cell image are closer, and the phase spectra of the two still contain the contour information of the target centroid. After the two-step preprocessing, the phase correlation method is used for registration, and the corresponding target centroids in the bright field cell image and the fluorescent cell image are aligned, and the registration of the bright field cell image and the fluorescent cell image is more accurate and stable.

[0047] Figure 7 The structural block diagram of the cell image registration device provided in the second embodiment of the present invention is as follows: Figure 7 As shown, the device includes: an acquisition unit 71, a negation unit 72, an corrosion unit 73 and a registration unit 74.

[0048] The acquisition unit 71 is used to acquire a first bright field cell image and a first fluorescent cell image.

[0049] The inversion unit 72 is used to invert the brightness of the background and target of the first bright field cell image to obtain a second bright field cell image, and use the first fluorescent cell image as the second fluorescent cell image.

[0050] The corrosion unit 73 is used to perform corrosion processing on the second bright field cell image and the second fluorescent cell image, whichever has a larger number of pixels covered by the target, to obtain a third bright field cell image and a third fluorescent cell image.

[0051] The registration unit 74 is used to register the first bright field cell image and the first fluorescent cell image according to the phase correlation method, the third bright field cell image and the third fluorescent cell image.

[0052] Preferably, the negation unit 72 specifically sets the pixel value of the pixel where the background of the first bright field cell image is located to 0, and sets the pixel value of the pixel where the target of the first bright field cell image is located to 255, so as to obtain the second bright field cell image.

[0053] Preferably, the corrosion unit 73 includes a comparison subunit and a corrosion subunit.

[0054] The comparison subunit is used to compare the number of pixels covered by the target in the second bright field cell image and the second fluorescent cell image.

[0055] The corrosion subunit is used to perform corrosion processing on the second bright field cell image if the number of pixels covered by the target in the second bright field cell image is large; and to perform corrosion processing on the second fluorescent cell image if the number of pixels covered by the target in the second fluorescent cell image is large.

[0056] Furthermore, the structural element of the corrosion process is a four-neighborhood template.

[0057] Preferably, the registration unit 74 includes a Fourier transform subunit, an inverse Fourier transform subunit and a registration subunit.

[0058] The Fourier transform subunit is used to calculate the cross power spectrum of the third bright field cell image and the third fluorescent cell image after Fourier transform.

[0059] The inverse Fourier transform subunit is used to perform inverse Fourier transform on the cross power spectrum to obtain the offset of the third bright field cell image and the third fluorescent cell image in the two-dimensional direction.

[0060] The registration subunit is used to register the first bright field cell image and the first fluorescent cell image according to the offset in the two-dimensional direction.

[0061] In the embodiment of the present invention, before the bright field cell image and the fluorescent cell image are registered by the phase correlation method, the brightness of the background and the target of the bright field cell image are first reversed, so that the directions of the relative brightness of the background and the target in the bright field cell image and the fluorescent cell image are the same, which does not affect the phase spectrum of the bright field cell image and can avoid the possibility of failure of subsequent registration by the phase correlation method; then, the bright field cell image and the fluorescent cell image with a larger number of pixels covered by the target are corroded, so that the corresponding target size and shape in the bright field cell image and the fluorescent cell image are closer, and the phase spectra of the two still contain the contour information of the target centroid. After the two-step preprocessing, the phase correlation method is used for registration, and the corresponding target centroids in the bright field cell image and the fluorescent cell image are aligned, and the registration of the bright field cell image and the fluorescent cell image is more accurate and stable.

[0062] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A cell image registration method, characterized in that: The method comprises: acquiring a first bright field cell image and a first fluorescent cell image; Inverting the brightness of the background and target of the first bright field cell image to obtain a second bright field cell image, and using the first fluorescent cell image as a second fluorescent cell image; Performing corrosion processing on the second bright field cell image and the second fluorescent cell image, whichever has a larger number of pixels covered by the target, to obtain a third bright field cell image and a third fluorescent cell image; registering the first bright field cell image and the first fluorescent cell image according to a phase correlation method, the third bright field cell image and the third fluorescent cell image; Registering the first bright field cell image and the first fluorescent cell image according to the phase correlation method, the third bright field cell image and the third fluorescent cell image comprises: Calculating a mutual power spectrum of the third bright field cell image and the third fluorescent cell image after Fourier transformation; Performing an inverse Fourier transform on the cross power spectrum to obtain an offset between the third bright field cell image and the third fluorescent cell image in a two-dimensional direction; The first bright field cell image and the first fluorescent cell image are registered according to the offset in the two-dimensional direction.

2. The method according to claim 1, characterized in that Inverting the brightness of the background and the target of the first bright field cell image to obtain a second bright field cell image includes: The pixel values ​​of the pixels where the background of the first bright field cell image is located are set to 0, and the pixel values ​​of the pixels where the target of the first bright field cell image is located are set to 255, so as to obtain a second bright field cell image.

3. The method according to claim 2, characterized in that The corroding process of the second bright field cell image and the second fluorescent cell image, whichever has a larger number of pixels covered by the target, comprises: comparing the number of pixels covered by the target in the second bright field cell image and the second fluorescent cell image; If the number of pixels covered by the target in the second bright field cell image is large, performing corrosion processing on the second bright field cell image; If the number of pixels covered by the target in the second fluorescent cell image is large, the second fluorescent cell image is corroded.

4. The method according to claim 3, characterized in that The structural element of the corrosion process is a four-neighborhood template.

5. A cell image registration device, characterized in that: The device comprises: An acquisition unit, used for acquiring a first bright field cell image and a first fluorescent cell image; an inversion unit, configured to invert the brightness of the background and the target of the first bright field cell image to obtain a second bright field cell image, and use the first fluorescent cell image as a second fluorescent cell image; an erosion unit, configured to perform an erosion process on the second bright field cell image and the second fluorescent cell image, whichever has a larger number of pixels covered by the target, to obtain a third bright field cell image and a third fluorescent cell image; a registration unit, configured to register the first bright field cell image and the first fluorescent cell image according to a phase correlation method, the third bright field cell image and the third fluorescent cell image; The registration unit comprises: A Fourier transform subunit, used for calculating the cross power spectrum of the third bright field cell image and the third fluorescent cell image after Fourier transform; an inverse Fourier transform subunit, configured to perform an inverse Fourier transform on the cross power spectrum to obtain an offset between the third bright field cell image and the third fluorescent cell image in a two-dimensional direction; A registration subunit is used to register the first bright field cell image and the first fluorescent cell image according to the offset in the two-dimensional direction.

6. The device according to claim 5, characterized in that The negation unit is specifically used to set the pixel value of the pixel where the background of the first bright field cell image is located to 0, and set the pixel value of the pixel where the target of the first bright field cell image is located to 255, so as to obtain the second bright field cell image.

7. The device according to claim 6, characterized in that The corrosion unit comprises: a comparison subunit, used to compare the number of pixels covered by the target in the second bright field cell image and the second fluorescent cell image; The corrosion subunit is used to, if the number of pixels covered by the target in the second bright field cell image is large, perform corrosion processing on the second bright field cell image; if the number of pixels covered by the target in the second fluorescent cell image is large, perform corrosion processing on the second fluorescent cell image.

8. The device according to claim 7, characterized in that The structural element of the corrosion process is a four-neighborhood template.

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