Patent Application
20100284582
1. Field of the Invention
The invention relates to the field of image processing and, in particular, to the field of processing dermatological images. More particularly, the invention relates to the acquisition and processing of images for detecting changing lesions. A particularly worthwhile application of the invention therefore relates to the detection of acneic lesions in the skin by image processing.
2. Description of the Relevant Art
The appearance and the change in a dermatological pathology, such as acne, can be monitored by image processing. However this requires, in this case, using records of successive snapshots obtained at different times of an organ to be monitored, in this instance the skin, and comparing the data thus obtained in order to detect the appearance and the development of new lesions or conversely their disappearance.
In this respect, it is possible to refer to document EP A 0 927 405 and to document FR A 2 830 961 in which the detection of an acneic lesion is carried out by comparing, two by two, images taken successively over time in order to detect and locate zones of differences between the images.
In particular, in document EP A 0 927 405, provision is made for calculating a deformation applied to a first image in order to make it match a second image formed subsequently, this deformation then being used as a basis for the detection of the lesions.
In light of the foregoing, it is desirable to alleviate the drawbacks associated with the detection techniques according to the prior art and, in particular, to propose a method and a device for detecting changing lesions that do not require the use of image comparisons.
On embodiment is directed to a method for acquiring and processing images for detecting changing lesions.
This method includes:
According to an embodiment of the method, a profile of change in the intensity of the image is generated for various color components of the images.
It is thus possible to generate a profile of change in the intensity of the image for at least one color component chosen from a red component, a blue component and a green component.
It is also possible to generate a profile of variation of the value of a ratio of color components of the images such as, for example, a profile of variation of the ratio between the intensity of the red component and of the blue component.
According to an embodiment, during the formation of the images, successive snap shots of said surface are taken according to different lighting methods, so that, at each snap shot moment, a set of obtained images is formed according to successive lighting methods.
The method can therefore also include storing the formed images in an image base and of viewing the images by selecting the images and displaying the selected images on a display screen.
During viewing an image, it is also possible to delimit an area of interest in the image and insert into the image being viewed a matching zone of an image formed according to another lighting method and extracted from the image base.
The method may also include processing the formed images by geometric matching of the images.
In an embodiment, a device for acquiring and processing images for detecting changing lesions includes image acquisition means suitable for the formation of successive images of a surface to be analyzed and image processing means.
According to a general feature of this device, the processing means includes calculation means suitable for generating at least one profile of change as a function of time of a parameter of the formed images and means for comparing at least one generated profile with a lesion detection threshold value.
For example, the parameter includes at least one parameter chosen from the intensity of the images for a red component, the intensity of the images for a blue component, the intensity of the images for a green component, and a ratio of color components of the images.
According to an embodiment of the device, the device includes lighting means suitable, in conjunction with the image acquisition means, for the formation of images according to different lighting methods, an image base for the storage of the formed images, a display screen for the viewing of the images extracted from the image base and a man machine interface suitable for delimiting an area of interest in an image being viewed, the processing means including means for inserting into said image a matching zone of an image formed according to a different lighting method and extracted from the image base.
Other objects, features and advantages of the invention will appear on reading the following description, given solely as a nonlimiting example, and made with reference to the appended drawings, in which:
While the invention may be susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
With reference to
In the exemplary embodiment shown, this device is designed to monitor the change over time of acned lesions by taking successive snapshots over predetermined periods of time of the skin of a patient, and archiving the images formed, displaying them and comparing them.
It will be noted however that such a device is designed to monitor the change over time of changing lesions, such as acne, psoriasis, rosacea, pigment disorders, onychomycosis, actinic keratosis and skin cancers.
Such a device can therefore advantageously be used by practitioners to determine the effectiveness of a treatment or, for example, to run clinical tests in order, in the same way, to assess the effectiveness of a new product.
It must be noted however that the invention is not limited to use in the dermatology field and may also be applied mutatis mutandis to any other field in which it is necessary to carry out a comparative analysis of successive images of an organ or, in general, of a surface to be examined.
It should similarly be noted that no departure is made from the context of the invention when the change over time of changing lesions is monitored based on a periodic acquisition of data of other types, on archiving of these data and on subsequent processing of these data.
As can be seen in
Specifically, in the exemplary embodiment envisaged in which the device 10 is designed to allow a practitioner or a research laboratory to determine the effectiveness of a treatment, the patient P undergoes examination sessions, for example at the rate of one every day, for a period that may be of the order of one month and, on each visit, the user takes pictures according to various lighting methods used respectively to assess various features of the lesions or to acquire data relating to parameters of the skin of the patient.
For example, pictures are taken that are lit with natural light, with parallel-polarized light and with cross-polarized light.
Specifically, the parallel-polarized light makes it easy to assess the reliefs of the lesions while cross-polarized light makes it easier to count the inflamed lesions by improving their display.
The picture-taking methods may also be carried out by UVA lighting or irradiation, in near infrared, by using infrared thermography, or with various wavelengths (multispectral images). It is also possible to carry out an arithmetic combination of these images thus formed.
It is also possible to use other types of lighting or else to combine the formed images with additional data obtained with the aid of appropriate measurement means.
Therefore, in a nonlimiting manner, it would also be possible to combine the image data with data obtained by means of various measurement devices, for example by means of an evaporimeter in order to determine the insensible loss of water from the skin, by means of a sebum meter, in order to determine the ratio of skin sebum or by means of a pH meter for the purpose of determining, for example, the changes sustained by the skin because of a treatment that may be irritating, etc. It would also be possible to associate with the image data information relating to the microcirculation or the desquamation of the skin by using appropriate measurement apparatus, or else relating to hydration by using, for example, a corneometer.
The lighting device 14 incorporates various lighting means making it possible to emit the chosen radiation, for example, as indicated above, according to a normal light, a parallel- or perpendicular-polarized light. However, in other embodiments, the lighting device 14 may also incorporate, if it is desired, a source of UVA rays, a source of rays emitting in the near-infrared field, or in the infrared field or else according to different wavelengths in order to form multispectral images or for the purpose of producing arithmetic combinations of such images.
As can be seen from
As can be seen, the device 10 can communicate via a wire or wireless link with a remote user terminal 19 or with a network of such terminals making it possible, for example, to remotely retrieve, view, compare and exploit the images stored in the database 16.
Finally, for the purpose of making the picture-taking conditions substantially reproducible, the device 10 is supplemented by a support 20 placed at a distance and at a fixed height relative to the camera 12 in order to allow a precise positioning of the zone of the body of the patient P relative to the latter.
The support 20 may advantageously be supplemented by additional means making it possible to accurately position and maintain the chosen bodily zone, for example in the form of a chin rest or resting surfaces for the head of the patient so that, on each visit, the face of the patient is positioned precisely relative to the camera.
However, in order to improve the performance of the device and to make the images comparable with one another by placing the parts of the body in exact correspondence from one examination to another, the central unit carries out a preprocessing of the formed images by geometric repositioning of the images.
Depending on the case, this repositioning may be rigid, that is to say that it does not change the shapes, or else nonrigid, or else affine, and will therefore change the shapes according to a certain number of degrees of freedom.
As will be described in detail below, this repositioning is carried out relative to a reference image, that is to say, on the one hand, relative to an image formed during a reference examination and, on the other hand, relative to a reference image. For example, this reference image may consist of an image taken according to a predetermined acquisition method, for example taken under natural light.
After this preprocessing has taken place, the images, previously organized, are stored in the image base 16 so that they can subsequently be viewed and compared.
To do this, with reference to
It thus includes, in the envisaged embodiment, a first module 21 for managing images or data, making it possible to group together patients suffering from one and the same pathology or to create a clinical study relating, for example, to a treatment the performance of which needs to be assessed, or to select an existing study.
This module 21 makes it possible to define and organize, in the database 16, a memory zone given an identifier and containing a certain number of patients, a set of visits, specific picture-taking methods, photographed zones of the body, or even areas of interest in the stored images and parameters to be monitored, originating from the measurement devices.
For example, during the creation of a study via the module 21, the user determines a reference picture-taking method onto which the other images will subsequently be repositioned.
The first management module 21 is associated with a second image-management module 22 which makes it possible to import images into the device 10 and to link them with a previously-created study, to a patient, to a visit, to an area of interest and to a picture-taking method.
The central unit 15 is also provided with an image-repositioning module 23.
This repositioning module 23 includes a first stage 23a repositioning all the images formed during the various visits onto one reference visit and a second stage 23b repositioning the images of each visit on a reference image taken according to a predetermined picture-taking method, in this instance in natural light.
With reference to
This involves, in other words, specifying a set of reference zones Zref the number and surface area of which can be programmed and comparing each of the zones Zref with the reference image Iref for example by scanning each reference zone on the reference image.
In practice, this comparison consists in generating a criterion of similarity, for example a coefficient of correlation of the reference zones Zref with the reference image and therefore consists in finding in the reference image the zone Z′ref that is most similar to each reference zone Zref of the image Ito be repositioned.
As can be seen in
This involves, in other words, finding the affine or free transformation which makes it possible to represent the vector field best and applying this transformation to the whole of the image.
Since the skin is an elastic material, it has been found that a nonrigid repositioning, that is to say nonaffine, allows a better repositioning of the images after regularization of the vector field, which makes it possible to impose constraints on the transformation and not allow every type of transformation.
Also offered to the user is a representation of the transformation made in order to validate or invalidate the repositioning of an image and thereby prevent a subsequent comparison of images in which the modifications made are too great.
For example, in order to do this, the user superposes on an image to be repositioned a grid or, in general, a notional grid, and applies the same transformation to this grid as that sustained during the repositioning of the images. It is therefore possible to easily assess the level of deformation applied to the image.
After having carried out the repositioning, the central unit 15 can, optionally, correct skewing in the image by correcting the intensity of the repositioned image so that its intensity is similar to the reference image.
After having carried out this preprocessing, the central unit 15 stores the images in the image base 16, the images associated, as appropriate, as indicated above, with additional data. For this purpose, it uses a module 24 for generating a set of repositioned images in order, in particular, to be able to export the images so that they can be used in processing software programs of other types.
The central unit 15 also includes a dynamic module for displaying the set of repositioned images, indicated by the general reference number 25.
This module 25 can be programmed directly via the man-machine interface 17 combined with the screen 18 and includes all the hardware and software means for navigating within the image base 16 in order to display the set of repositioned images, to adjust the display parameters, such as the zoom, the luminosity, the contrast, the picture-taking method displayed, to delimit areas of interest or else, as will be described in detail below, to incorporate in a delimited area in an image being displayed a matching area extracted from another image, for example an image taken according to another picture-taking method.
With reference to
First of all, with reference to
A second window F2 (
In addition, a control window F3 (
The central unit 15 can also offer a control window F4 making it possible to adjust the degree of zoom, luminosity and contrast of the displayed image (
With reference to
Therefore, for example, after having selected an area of interest R and another picture-taking method, the central unit 15 and, in particular, the processing module 26, extracts from the image corresponding to the selection the zone Z matching the area of interest and inserts it in the image in order to be able to dynamically have another picture-taking method in a selected portion of an image being displayed.
Naturally, any other data item extracted from the base, or only a portion of these data, may also be incorporated into the area of interest R instead of or in addition to the imported zone Z, for example any type of data obtained by the various devices for measuring a parameter of the skin, such as pH data, insensible water loss, sebum metric, hydration data such as for example the skinchip or corneometry, microcirculation, desquamation, color or elasticity of the skin.
Finally, also with reference to
Specifically, with reference to
In contrast, as shown in
It is then possible to detect and automatically qualify the appearance of a lesion by comparing the intensity profiles with a threshold value. For example, as shown, it is possible to compare the profile of variation of the ratio of the red/blue signals with a threshold value of intensity corresponding to a value “2”.
Therefore, as emerges from
As indicated above, the monitored parameter may consist of any type of parameter associated with the images, and in particular a colorimetry parameter, that is to say, in particular, the intensity of the red, green and blue components and the component ratio, for example the ratio between the intensity of the red component and of the blue component.
The module 27 thus collects all the values of the parameters monitored over a programmable period of time and generates curves illustrating the change in these parameters in order to present them to the user. As shown in
For each of the monitored zones, the detection module 27 calculates the difference in the value of the parameters compared with a corresponding lesion-detection threshold value.
Naturally, this calculation is made after the user has selected one or more parameters, depending on the type of lesion to be detected and, if necessary, after the user has entered a threshold value or several respective threshold values.
Specifically, the threshold value which may be stored in memory in the central unit 15 or entered manually can be programmed and depends on the monitored parameter.
As indicated above, the appearance of a lesion is reflected by a variation, in the damaged zone, in the color components. In the example illustrated in
In this instance therefore it is possible to detect the appearance of the lesion based on the variation in the ratio of the red and blue components, by comparison with a detection threshold value for example set at “2”.
Naturally, another threshold value is used when a lesion is detected based on another parameter.
A lesion is detected by the module 27, zone by zone. Naturally, the dimensions of the monitored zones are a programmable value which depends on the size of the lesions to be detected.
Finally described with reference to
During a first step 30, the central unit 15 successively acquires a set of images taken successively over time during various visits by a patient and, for each visit, according to various picture-taking methods.
Subsequently or beforehand, the central unit 15 uses the study management modules and management modules 21 and 22 in order to create a study and to assign the images formed to a previously entered study.
During the next step 32, the images are repositioned, according to the above-mentioned procedure, by using the modules 23a and 23b for repositioning the images in order, on the one hand, to reposition the images on a reference visit and, on the other hand, to reposition, on each visit, an image on a reference image taken according to a selected picture-taking method.
After repositioning, a set of repositioned images is generated (step 33) said images then being stored in the image base 16. As indicated above, the image data may be supplemented by data delivered by other types of sensors in order to supplement the available information.
During the next phase 34, at the request of a user, the images stored in the image base 16, supplemented, as necessary, by supplementary data or a portion of such data, can be displayed.
To do so, the central unit 15 offers the user a certain number of interfaces making it possible to select display parameters, choose one or more areas of interest, and navigate from one image to another within the area of interest, to choose various zones of a face, etc.
Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0755306 | May 2007 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR08/50922 | 5/28/2008 | WO | 00 | 7/23/2010 |
