EP3715721A1 - Cooking device and method for operating a cooking device - Google Patents

Abstract

The present invention relates to a method for operating a cooking appliance (1) with a cooking area (11) for the preparation of food, the food in the cooking area (11) being monitored during the cooking process and images over time by means of a camera device (3) of the cooking area can be detected, the images each consisting of a plurality of picture elements and being evaluated by means of a processing device (4). Image elements that change over time are identified and assigned as belonging to the item to be cooked, in order to enable a distinction to be made from the image elements originating from outside the item to be cooked.

Description

The present invention relates to a method for operating a cooking appliance with at least one cooking area for preparing food to be cooked. The food is monitored in the cooking area during the cooking process. For this purpose, images of the cooking area are recorded over time by means of at least one camera device.

For an optimal cooking result, it is usually crucial to consider certain properties of the food. Such information about the food to be cooked is particularly important for the reliable running of automatic programs. It is particularly convenient if certain properties of the food can be recorded and taken into account by the cooking device during the cooking process and also independently and without contact. For this purpose, for example, cooking appliances have become known in which the food to be cooked is observed with a camera. With regard to reliability and practicality, it is desirable to further improve the known solutions.

It is therefore the object of the present invention to enable an improved monitoring of food in a cooking space during a cooking process. In particular, the monitoring should take place with a camera device.

This object is achieved by a method with the features of claim 1 and by a cooking appliance with the features of claim 16. Preferred features are the subject matter of the dependent claims. Further advantages and features emerge from the general description of the invention and the description of the exemplary embodiments.

The method according to the invention is used to operate a cooking appliance, in particular an oven with at least one lockable cooking space. The cooking device comprises at least one cooking area for preparing food. The food is monitored in the cooking area during the cooking process. For this purpose, images of the cooking area are recorded over time by means of at least one camera device. The images each consist of a large number of picture elements. All of the direct measurands that are accessible for the entire image are also accessible for each image element. The images are evaluated by means of at least one processing device. Image elements that change over time are identified and assigned as belonging to the item to be cooked, in order to enable a distinction to be made from the image elements in the cooking area that originate from outside the item to be cooked.

The method according to the invention offers many advantages. A considerable advantage is that the image elements originating from the food to be cooked contain the properties of the food to be cooked without any falsification, and information is therefore available for further processing or evaluation which actually originates from the food to be cooked with particularly high reliability. Disturbing or irrelevant influences from outside the food to be cooked can then be evaluated or masked out accordingly. This enables significantly improved monitoring of the food to be cooked. In this way, a particularly meaningful characterization of certain cooking product properties can take place. With the invention, for example, automatic programs can be adapted very specifically to the respective cooking product or the respective cooking process, so that particularly tasty cooking results can be achieved.

The special feature of the identification according to the invention lies in the time factor, which is available during cooking processes and which makes it particularly easy to identify the food being cooked. Recognizing in a still image where the food to be cooked is located is extraordinarily difficult and, if at all, only halfway satisfactorily achieved with methods of artificial intelligence. In the method described here, in contrast to the still image, use is made of the fact that a sequence of images about the cooking process can be recorded during cooking, for which it can be observed how individual image elements develop over time. Image elements that contain food to be cooked behave completely differently than image elements that contain the cooking area with cooking space walls, vessels and the like. This otherness does not only refer to the change caused by tanning and discoloration, but also e.g. B. also on distances due to volume changes or changes in surface temperature.

The images are recorded in particular during at least one time segment of the cooking process. In particular, the image elements that change during at least one time segment of the cooking process are identified. In particular, the camera device records images of the cooking area over a period of time in which the food to be cooked is treated and, in particular, warmed or heated. In particular, the image elements that change during the treatment and in particular during the heating or heating are identified and assigned accordingly. The images recorded over time are in particular an image sequence. In particular, the food to be cooked is arranged in the cooking area during the cooking process. In the context of the present invention, the food to be cooked is in particular not understood as part of the cooking area, even if it is positioned there.

In particular, the camera device comprises a large number of sensor segments. In this case, at least one image element from the cooking area can preferably be detected in a spatially resolved manner with at least one sensor segment. A picture element is in particular assigned to at least one sensor segment of the camera device or in at least one mapped to a sensor segment. In the context of the present invention, picture element and pixel can be used synonymously.

Preferably, those image elements are assigned to the food which have a minimum change over time. The image elements of the food to be cooked can thus be recognized particularly reliably. In the case of cooking processes, it is usually only the food that is changed due to the heating. Other parts do not change or only change at the beginning of the cooking process. For example, the walls of the cooking space essentially no longer heat up after heating and change their color and geometry only insignificantly compared to corresponding changes in the food. In particular, the minimum change is determined in such a way that a false positive assignment is reliably counteracted. In particular, those picture elements are assigned to the food which have a rate of change over time above a threshold value.

Preferably, those image elements are not assigned to the food to be cooked and / or are assigned to the cooking area which do not achieve a minimum change over time. For example, it is the walls of the cooking space and the food carriers that are not changed during the cooking process or after heating. In the holding phase of the cooking space temperature, there is no significant temperature change in these components either. In particular, those image elements are not assigned to the food and / or are assigned to the cooking area which have a rate of change over time below a threshold value. At least one time interval is preferably defined over which the minimum change must exist.

It is possible that image elements assigned to the food to be cooked are not taken into account for the further evaluation if these image elements do not achieve a minimum change over time. This enables particularly reliable detection of relevant image areas. For example, it is possible that apples in a cake batter are not taken into account for an evaluation of the browning process. In this way, only the browning of the dough can be specifically monitored without the apples falsifying the result. In particular, image elements assigned to the food to be cooked are not taken into account for the further evaluation if they lie outside a course corridor. The course corridor can be determined, for example, at the beginning or in an early phase of the cooking process or also later on the basis of the data already recorded at this point in time.

It is also possible that those image elements remain unconsidered and / or are not assigned to the food to be cooked, which deviate from at least one predetermined starting value at the beginning of the cooking process. This has the advantage that image elements with a content that cannot be reliably identified does not lead to undesirable deviations. The output value can be determined in advance, for example, and stored in the cooking appliance or in the processing device. It is also possible for the output value to be established or at least partially influenced on the basis of user inputs. The output value can be influenced or selected by entering the type of food to be cooked, for example baked goods, meat or vegetables.

Preferably, at least one change over time of at least one color information and / or brightness information and / or intensity information item is evaluated to identify the picture elements that change over time. Such an evaluation offers a particularly reliable identification of the food to be cooked. It is also possible for the identification of the image elements that change over time to be evaluated for at least one change over time of at least one other suitable characteristic variable of the image processing. In particular, those picture elements are assigned to the food which have a minimum change in color information and / or brightness information and / or intensity information over time. Such information can include, for example, a color coordinate and / or brightness coordinate and / or intensity coordinator.

In particular, color information and / or brightness information and / or intensity information lying outside a limit value are not taken into account for the evaluation. For example, purple or turquoise or other color values that are unusual for cooking or baking processes can be disregarded.

Particularly preferably, those image elements are assigned to the food which have an increase in browning and / or at least a change in a color value that is characteristic of browning, for example a red-green value, over time. In particular, those picture elements are assigned to the food which, over time, have an increase in another color value characteristic of browning. Depending on the type of value or representation of the value, it can also be provided that the image elements must have a decrease in such a value in order to be assigned to the food to be cooked. Since browning is a particularly characteristic feature for heating many foods, a particularly reliable and accurate assignment can be made.

In a preferred and particularly advantageous embodiment, the images captured by means of the camera device show temperature distributions in the cooking area. Preferably, at least one change in the temperature distributions over time is evaluated in order to identify the picture elements which change over time. The camera setup comprises in particular a thermal imaging camera or is designed as such. The images captured by means of the camera device are, in particular, thermal images. In particular, the camera device is suitable and designed to capture images in at least one infrared range. In particular, the camera device is designed as an IR camera.

In this case, a picture element corresponds in particular to a temperature value or comprises at least one such. In particular, temperatures from or from the cooking area can be detected in a spatially resolved manner by means of the camera device. Preferably, those image elements are assigned to the food which have a minimum change over time in the detected heat output and / or the temperature and / or an emissivity and / or a false color value for the temperature. It is also possible for those image elements to be assigned to the food which have a minimum change over time in another variable that can be detected by a thermal imaging camera.

In a likewise preferred and advantageous embodiment, the images captured by means of the camera device contain spatial image information from the cooking area. This offers a particularly advantageous monitoring. Spatial image information is understood to mean, in particular, three-dimensional image information. In order to identify the image elements that change over time, at least one change in the spatial image information over time, preferably a change in the distance between the surface of the food being cooked and the camera device, is evaluated. In particular, those image elements are assigned to the food which have a minimum change over time in the spatial image information and in particular in the distance. In particular, those image elements are not assigned to the food to be cooked and / or are assigned to the cooking area which do not achieve a minimum change in the spatial image information and in particular the distance over time.

Those image elements are preferably assigned to the food to be cooked, the distance between which increases and / or decreases by a certain minimum amount over time. Whether an increase or decrease is necessary depends, for example, on the positioning of the camera device in relation to the food to be cooked. If the camera device is arranged above or above the item to be cooked, a decrease in the distance or an increase in the height of the item to be cooked is particularly typical for the detection of baked goods. Baked goods usually rise during preparation in the oven and thus gain height. For other items to be cooked and for example for a roast or meat, however, the increase in the distance or the decrease in height can be a characteristic feature for the assignment of the image elements to the item to be cooked. Spatial image information thus enables particularly meaningful monitoring of the food to be cooked.

The camera device in particular comprises at least one 3D camera or is designed as such. In particular, the camera device is suitable and designed to capture images with three-dimensional image information or three-dimensional images from the cooking area. In particular, the image elements provide spatially resolved three-dimensional information from the cooking area. The 3D camera is operated, for example, according to the TOF (time of flight) principle. Other designs for 3D cameras are also possible.

In an advantageous embodiment, at least one course corridor is calculated and / or taken into account during the cooking process, which describes an expected change over time for image elements of the food to be cooked. In particular, image elements which lie outside the course corridor are not taken into account and / or are not assigned to the food to be cooked. The course corridor can be determined, for example, at the beginning or in an early phase of the cooking process or also later on the basis of the data already recorded at this point in time. A previously determined course corridor can also be stored. The course corridor can be calculated from data from the current cooking process. The course corridor is preferably calculated from the change over time in the image elements recorded up to that point. It is possible that the course corridor is calculated from a mean value and / or a standard deviation or the like or corresponds to such. The course corridor can be dependent on a set automatic program and / or on a preselected type of food. Such a course corridor offers many advantages for recognizing the food to be cooked. In addition or as an alternative to the course corridor, a target value can also be calculated which an image element must have at the end of the time change in order to be assigned to the food or the cooking area.

In particular, the image elements of the food to be cooked are identified or assigned within the first 20 minutes and preferably within the first 10 minutes after the start of the cooking process. During this period, the changes in the food due to heating are particularly characteristic, so that a particularly reliable assignment can be made. In particular, the image elements of the food to be cooked are assigned after a maximum of 20 minutes and preferably after a maximum of 10 minutes after the start of the cooking process. It is also possible that the image elements of the food to be cooked are assigned within the first 5 minutes or less. It is also possible for the image elements of the food to be assigned within the first 30 minutes or 40 minutes or within the first hour. It is possible that the time period for the assignment is based on a set automatic program and / or a preselected type of food.

In all of the configurations, it is particularly preferred that the image elements assigned to the item to be cooked are subjected to an evaluation to determine a ready time and / or a Surface expansion and / or a spatial expansion of the food to be cooked. Due to the particularly reliable detection of the food to be cooked, the time of completion can be determined particularly reliably and precisely. In addition, the surface extent or spatial extent can be determined considerably more reliably if the areas belonging to the food to be cooked have been identified beforehand.

It is also possible for the image elements assigned to the food to be cooked to be subjected to at least one other evaluation. For example, the image elements can be analyzed with regard to the homogeneity of the ingredients and / or for browning differences on the surface or the like. The image elements assigned to the item to be cooked can also be subjected to an evaluation to determine another property to be cooked, for example to determine the type of food to be cooked. In this way it can be recognized whether it is pasta or meat or fish or vegetables or fruit.

The image elements that change over time are particularly preferably identified, taking into account at least one automatic program set for the cooking process and / or at least one preselected type of food being cooked. In particular, a minimum change over time and / or an initial value is defined as a function of the automatic program and / or the type of food being cooked. For example, a different minimum change in time may be necessary for pasta than for roasting so that image elements are assigned to the food to be cooked. It is preferred that at least one value for the minimum change and / or the initial value are determined as a function of at least one automatic program and / or as a function of at least one preselected type of food to be cooked.

In all of the configurations it is particularly preferred that the cooking appliance is designed with a cooking space. The cooking area is preferably located in or corresponds to the cooking space, so that the food in the cooking space is monitored during the cooking process. In particular, the cooking device is designed as an oven. In particular, the cooking space can be closed by at least one cooking space door. In particular, the cooking space is designed to be heatable. When preparing food in a heatable cooking space, the method presented here enables particularly reliable monitoring and also a particularly reproducible determination of the time of preparation.

However, it is also possible that the cooking device is designed with a hob and that the cooking area lies on or corresponds to the hob. In particular, the food on the hob is monitored during the cooking process. It is possible that the camera device is located in an extractor hood and / or Lighting device and / or kitchen furniture or the like is arranged. Another arrangement of the camera device in relation to the hob is also possible. In particular, the camera device records the time images of the cooking space and / or the hob. The method presented here also offers advantageous monitoring with a hob.

The cooking appliance according to the invention can be operated according to the method described above. In particular, the cooking appliance is suitable and designed to be operated according to the method described above. The method described above is used in particular to operate the cooking appliance according to the invention.

The cooking appliance according to the invention also offers many advantages and enables considerably improved monitoring of the food in the cooking area. In particular, the cooking appliance comprises at least one cooking space and / or at least one hob. The cooking space and / or the hob provide in particular at least part of the cooking area or are designed as such.

The camera device is arranged in particular on a component of the cooking appliance, so that the image information can be transported from the cooking area to the camera device without hindrance. If the camera device is not in direct line of sight to the cooking space, an optical path is created, in particular by means of at least one component, which ensures the transport of information. Such components are, for example, mirrors and / or lenses and / or screens or the like.

Further advantages and features of the present invention emerge from the exemplary embodiments, which are explained below with reference to the accompanying figures.

Figur 1

eine rein schematische Darstellung eines erfindungsgemäßen Gargerätes in einer Vorderansicht; und

Figur 2

eine rein schematische Darstellung eines anderen erfindungsgemäßen Gargerätes in einer perspektivischen Ansicht.

Show it:

Figure 1

a purely schematic representation of a cooking device according to the invention in a front view; and

Figure 2

a purely schematic representation of another cooking device according to the invention in a perspective view.

The Figure 1 shows a cooking device 1 according to the invention, which is designed here as an oven 100. The cooking appliance 1 is operated according to the method according to the invention. The cooking appliance 1 has a cooking area 11, which here is provided by a heatable cooking space 21 provided. The cooking chamber 21 can be closed by a cooking chamber door 31. The cooking device 1 is provided here as a built-in device. It can also be designed as a stand-alone device.

For the preparation of food to be cooked, a treatment device 2 is provided which, in the view shown here, is not visible in the cooking space 21 or inside the device. The treatment device 2 comprises, for. B. a heating device with several heating sources for heating the cooking space 21. As a heating source, for example, a top heat and / or a bottom heat, a hot air heat source and / or a grill heat source or other types of heat sources can be provided. A steam generator can also be provided. In addition, the treatment device 2 can be designed for heating or cooking with high-frequency radiation and for this purpose can comprise at least one high-frequency generator.

The cooking appliance 1 here comprises a control device, which is not shown in detail and which is operatively connected to the treatment device 2, for controlling or regulating device functions and operating states. Preselectable operating modes and preferably also various automatic programs or program operating modes and other automatic functions can be executed via the control device. The control device controls z. B. the treatment device 2 depending on a preselected operating mode or automatic program accordingly.

An operating device 101 is provided for operating the cooking appliance 1. For example, the operating mode, the cooking space temperature and / or an automatic program or a program operating mode or other automatic function can be selected and set. Further user inputs can also be made via the operating device 101 and, for example, menu control can be performed. The operating device 101 also includes a display device 102 via which user instructions and z. B. Prompts can be displayed. The operating device 101 can comprise operating elements and / or a touch-sensitive display device 102 or a touchscreen.

To monitor the food to be cooked during a cooking process, images of the cooking area 11 are captured by means of a camera device 3. In the view shown here, the camera device 3 is not visible in the interior of the device or in the cooking chamber 21. The images consist of a large number of picture elements or pixels. For this purpose, the camera device 3 is designed with a sensor with a multiplicity of sensor segments, so that the image information can be detected pixel by pixel or spatially resolved.

In order to distinguish the food to be cooked from its surroundings or from the cooking area 11, those image elements are identified by means of a processing device 4 which are change during the cooking process. The picture elements, which for example have a minimum change over time, are then assigned to the food to be cooked. Image elements without a change or below a minimum change over time are assigned to the cooking area 11. Since the food to be cooked changes during preparation, but the surroundings show no changes at all or only very few changes, the recorded images can be used to differentiate very reliably between the food to be cooked and the cooking area 11.

The camera device 3 is designed, for example, as a thermal imaging camera or IR camera. In the process, thermal images are recorded which show temperature distributions in the cooking area 11. The individual image elements represent the temperatures in the cooking area 11 with spatial resolution. The identification of the food to be cooked here makes it possible to record the temperature of the food alone, without using, for example, a very imprecise mean value over the entire field of view of the camera. When cooking, the food and the cooking area usually have very different temperatures.

Those picture elements which show characteristic changes during the cooking process are then assigned to the food to be cooked. For example, many foods brown the surface when they are heated. This results in a change in the emissivity, which can be taken from the thermal images and which can thus be used to identify the image elements belonging to the food to be cooked. In contrast, the emissivity of the cooking area does not change.

In an exemplary measurement process, the camera device 3 captures a thermal image of the filled cooking space 21. This includes cooking space walls, food carriers and other components, as well as the food.

The IR camera sees the contents of the cooking space with the food, container, baking tray, grill grate, baking sheet holders, radiators, lamps, cooking space walls or general cooking accessories and cooking space accessories. The IR camera records a first thermal image at the beginning of a cooking process and it is initially unknown in which pixels of the IR camera the temperature of the food is recorded. Where this is the case will only become apparent during cooking.

Despite the same temperature everywhere in the cooking space, the different emissivity of the different materials (food, enamel, chrome-plated steel) in the thermal image of the IR camera, which determines the thermal radiation emitted by the object, results in a different temperature reading for each material.

The cooking process will start. The cooking space temperature rises. The IR camera continuously takes more thermal images.

The temperature measurement values increase in all pixels, more or less synchronously with the increase in temperature of the cooking space air. In the holding phase for the oven air temperature, the temperature in the thermal image of the IR camera rises for each object with different material properties or with a different emissivity to its own measured value for its holding temperature (in fact, all object temperatures in the cooking area are roughly the same, but the emissivity leads to different measured values in the thermal image of the IR camera). Only the temperature of the food remains at a different temperature level because it contains water that cannot be heated above around 100 ° C.

In the following, all temperatures fluctuate only with a temperature control-dependent amplitude around their mean value. The mean values are "somewhere" depending on the emissivity of the objects. The emissivity is a number between 0 and 1 (0% and 100%). An object with emissivity 1 (e.g. enamel) emits 10x more heat radiation at the same temperature than an object with emissivity 0.1 (e.g. chrome-plated steel).

With constant emissivity, the output of the emitted thermal radiation increases sharply with the thermal radiation. If the output of the emitted thermal radiation changes from an object, this can be interpreted as a change in the object temperature or as a change in the object's emissivity.

For the detection of the food to be cooked in the thermal image of the IR camera, it is now taken into account that the emissivity of the inorganic materials in the cooking chamber (glasses, metals, enamel, ...) does not change or changes only insignificantly. The temperature in the cooking space is in the holding phase and only fluctuates around its mean value with the control amplitude. This means that all cooking space and accessories fluctuate around their individual (radiation) temperatures in the thermal image of the IR camera. Nothing changes further. All pixels in which this finding is present do not belong to the food to be cooked.

Then there are pixels in which the temperature curve over time in the thermal image is different. Here, too, an increase to an individual holding temperature is initially observed in the thermal image, to actually around 100 ° C. Despite the unchanged conditions for temperature control, there is then a change in the temperature value in these pixels by which the control amplitude fluctuates. From this point in time, the food can be recognized.

The effect arises from the fact that on the one hand the surface temperature after the surface has dried out and the associated browning rises above the holding value of the initial phase (where there was still water on the surface) and on the other hand the organic material of the food changes chemically and physically and thus in the Its emissivity is also in step. Both lead to a different measured value in the thermal image of the IR camera. Depending on the food and surface changes, the temperature change in the thermal image can go in one direction or the other. It is only important that something changes, although the cooking space itself is in a stationary state after its heating-up phase. In order to detect pixels that capture the food, it is not necessary to know whether the temperature change in the thermal image is due to an actual temperature change on the surface of the food or due to a change in the emissivity. All pixels with this finding are very likely to be part of the food.

Another option for identifying the food to be cooked is to use a measuring probe to pierce the food in addition to the thermal imaging camera. The surface temperature of the food to be cooked is then determined by means of this measuring probe. Since the food to be cooked changes its color during the cooking process and, for example, is browned, there is a change in the emissivity of the food. Accordingly, there is a temperature difference between the temperature values of the measuring probe and the thermal image. Since the emissivity of the cooking area 11 does not change, no such temperature difference can be observed for its picture elements. It is thus possible to distinguish between the food and the cooking area 11 via this temperature difference.

Another implementation of this principle is to observe not the temperature difference but a tracking of the emissivity of the thermal imager. Since the emissivity of the food changes during preparation, the emissivity of the thermal imaging camera would have to be adjusted accordingly until its temperature readings match those of the measuring probe. Such tracking is not necessary for the cooking area 11, since its emissivity does not change. Reliable identification of the food to be cooked is thus also possible via the time deviation of the emissivity.

Additionally or alternatively, color information, brightness information and / or intensity information or other variables of the image processing can be evaluated to identify the picture elements that change over time. In such a case, the camera device 3 is designed, for example, to capture images in the visible and / or in the infrared range of light.

For example, many foods show a characteristic browning and thus a color change during preparation. For this purpose, the picture elements are identified which show a change in one or more color values during the cooking process. These picture elements are then assigned in the food.

For example, RGB color coordinates can be viewed for this purpose. It is also possible that color coordinates in the Lab color space (also referred to as L * a * b * color space or CIELAB) are considered.

With the Lab display, objects can be recognized particularly well that experience a change in brightness or color over time. The picture elements, which do not change in their brightness over time, are shown in white in the Lab display. The image elements that come from an object that has been tanned over time are also displayed correspondingly darker. For example, baked goods made from light-colored dough can be reliably identified. The component surfaces in the cooking area 11 do not experience any change in color and accordingly remain white in the Lab display. They can therefore be extracted very easily and reliably from further analysis. Even minor changes during baking are reliably detected.

After identification, the food can now be further observed, detached from the rest of the cooking area, and examined, for example, for an increase in browning. When a certain browning is reached, the baking process can be ended.

For the assignment to the food to be cooked, it can be a condition that the brightness must change by a certain amount in a defined time interval. Otherwise it is assumed that the picture element does not belong to the food. Another possibility is to only observe those picture elements that are already outside a minimal change window at a certain point in time during the cooking process. The picture elements with values within the change window are then assigned to the cooking area 11.

The picture elements can be restricted to a permissible start window. Image elements whose values lie outside the start window and show exotic colors, for example, are then sorted out or not assigned to the food to be cooked. If necessary, adapted start windows or adapted permissible start values can be provided for automatic programs or for foods or food groups (meat, baked goods, vegetables, etc.). For example, a different start window can be provided for a light dough than for a dark dough.

During the evaluation, the time course of the color coordinates of the picture elements to be observed can be followed. If the picture elements run out of a corridor over time, which z. B. is spanned by the color coordinates Lab, the picture elements are discarded for further observation with regard to the browning.

The spatial corridor is generated dynamically during the ongoing cooking process, for example. The corridor results z. B. from the trajectories of the remaining picture elements through the corresponding color space.

One possibility of forming a band for a permitted corridor is, for example, possible as follows. A mean value and the standard deviation of the lightness (L) are calculated for each point in time. The middle of the band results, for example, from the mean value. The range is a fraction to a multiple of the standard deviation. In this way, outliers that are too dark or too bright can be eliminated from the set of picture elements or the set of pixels. If a track falls out of the band at any point in time, it is no longer used for the further calculation of the mean value and standard deviation. This prevents the standard deviation caused by the outliers from becoming larger and larger as the cooking time progresses and the permissible channel from becoming wider and wider.

Colored target windows can also be set for the color coordinates, for example at the time of completion. If you work through the color space with accompanying (color) channels from start to finish, the start window and finish window are already part of the observation and are already included in the channels. By looking at the progression over time with different browning speeds and different initial colors, the various components of a cake can be differentiated, for example.

For example, if a marble cake is to be prepared, there are light and chocolate-colored dough in different areas. Thus the initial values are different. The discoloration also varies over time. Since the dark dough is already relatively dark at the beginning, it does not become as darker during the browning as a dough that is already light at the beginning. The chocolate-colored areas can be ignored by the design of the method described above. Only the areas that are light at the beginning can be specifically analyzed in order to determine the tan on them.

If, for example, an apple pie is to be prepared on a baking sheet, the apples brown much less slowly than the light batter. Although the light-colored dough makes up a smaller proportion of the surface area of a cake densely covered with apples, the previously described method can be used to specifically identify the image elements that show a significant browning (dough). First of all, consider all areas that are initially light (apples and dough). Then, however, only the areas that tan more quickly are considered. The other picture elements or the white pixels represent apples and are not included in the browning measurement or are less weighted. Be like that identifies those image elements that only represent the light dough in a simple and reliable manner. The browning is only determined on these and not averaged integrally over a surface of unknown composition.

The camera device 3 can also be designed as a 3D camera so that spatial image information from the cooking area 11 can be recorded. To identify the food to be cooked, for example, the distance between the camera device 3 and the objects recorded in the cooking area 11 is detected in a spatially resolved manner. Since the components of the cooking area 11 that do not belong to the food to be cooked do not change their distance from the camera device 3 during the cooking process, they can be reliably identified by this. In contrast, when a food is heated, changes in shape and thus changes in distance occur.

For example, a cake rises during baking, so that its height increases. With the arrangement of the camera device 3 shown here above the cooking area 11 or above the food to be cooked, this leads to a reduction in the distance. The image elements which have a decrease in distance can then be assigned to the food to be cooked.

Other foods, such as meat, fish or vegetables, usually shrink and shear during preparation. As a result, their height decreases or also increases at other points, so that with the arrangement of the camera device 3 shown here, an increase or decrease in the distance from the camera device 3 can be detected.

The identification of the food in the cooking area 11 presented here enables further sensory evaluations to be carried out particularly advantageously. For example, the area of the food can be determined from the perspective of the camera 3. For this purpose, the identification of the image elements with the food to be cooked must be carried out anew at each measurement time so that it can be recognized that the number of image elements with the food to be cooked has increased or decreased with the cooking time and by what amount. It can be determined how homogeneous a food is (raisin dough, several components in spouts). Diameter distributions for jacket potatoes, potato pieces or potato slices can be determined. In principle, it can be measured how fine-grained a food preparation is in order to estimate the required cooking time. Mean browning and browning differences on the surface can also be determined and monitored safely and reliably.

In the Figure 2 a cooking device 1 designed as a hob 41 is shown. The hob 41 here forms the cooking area 11. It is also possible for the cooking appliance 1 to be configured as one with a hob 41 equipped stove is formed. An extractor hood 103 is arranged here above the hob 41. The treatment device 2 here comprises a plurality of heatable hotplates.

The camera device 3 is housed here together with the processing device 4 in the extractor hood 103. The camera device 3 detects the cooking area 11 from there. The cooking appliance 1 is operated here according to the method according to the invention. The images are captured and evaluated, and the image elements belonging to the food to be cooked are identified, preferably as before with reference to the Figure 1 written.

List of reference symbols

1

Cooking appliance

2

Treatment facility

3

Camera setup

4th

Processing facility

11

Cooking area

21st

Cooking space

31

Oven door

41

Hob

100

oven

101

Control device

102

Display device

103

Extractor hood

Claims (16)

Method for operating a cooking appliance (1) with at least one cooking area (11) for the preparation of food to be cooked, the food in the cooking area (11) being monitored during the cooking process and with at least one camera device (3) recording images of the cooking area over time The images each consist of a large number of image elements and are evaluated by means of at least one processing device (4),
characterized,
that image elements that change over time are identified and assigned as belonging to the food to be cooked, in order to enable a distinction to be made from the image elements originating from outside the food to be cooked. Method according to the preceding claim, characterized in that those image elements are assigned to the food which have a minimum change over time. Method according to one of the preceding claims, characterized in that those picture elements are not assigned to the food and / or are assigned to the cooking area (11) which do not achieve a minimum change over time. Method according to one of the preceding claims, characterized in that image elements assigned to the food to be cooked are not taken into account for the further evaluation if they do not achieve a minimum change over time. Method according to one of the preceding claims, characterized in that those image elements remain unconsidered and / or are not assigned to the food to be cooked which deviate from at least one predetermined initial value at the beginning of the cooking process. Method according to one of the preceding claims, characterized in that at least one temporal change of at least one color information and / or brightness information and / or intensity information item is evaluated to identify the picture elements which change over time. Method according to one of the preceding claims, characterized in that color information and / or brightness information and / or intensity information lying outside a limit value are not taken into account for the evaluation. Method according to one of the preceding claims, characterized in that those picture elements are assigned to the food which have a decrease in brightness or an increase in browning and / or at least a change in a color value over time. Method according to one of the preceding claims, characterized in that the images captured by the camera device (3) show temperature distributions in the cooking area (11) and that at least one change in the temperature distributions over time is evaluated to identify the image elements that change over time. Method according to one of the preceding claims, characterized in that the images captured by means of the camera device (3) contain spatial image information from the cooking area (11) and that to identify the image elements that change over time, at least one change in the spatial image information over time, preferably one Change in distance to the camera device (3) is evaluated. Method according to one of the preceding claims, characterized in that at least one course corridor is calculated and / or taken into account during the cooking process, which describes an expected change in time for image elements of the food to be cooked and that image elements are not taken into account and / or are not assigned to the food to be cooked lie outside the corridor. Method according to one of the preceding claims, characterized in that the identification of the image elements of the food to be cooked takes place within the first 20 minutes and preferably within the first 10 minutes after the start of the cooking process. Method according to one of the preceding claims, characterized in that the image elements assigned to the food to be cooked are subjected to an evaluation to determine a property of the food to be cooked which changes during the cooking process. Method according to one of the preceding claims, characterized in that the identification of the picture elements that change over time takes into account at least one automatic program set for the cooking process and / or at least one preselected type of food being cooked. Method according to one of the preceding claims, characterized in that the cooking appliance (1) is designed with a cooking space (21) and that the cooking area (11) lies in or corresponds to the cooking space (21), so that the food in the cooking space (21) is monitored during the cooking process. Cooking appliance (1), suitable and designed for carrying out a method according to one of the preceding claims.

Images