System that displays an image based on a color-by-color pixel count and method thereof

A drop in visibility of display information is prevented while securing a clear view outside a vehicle. A display information extracting unit is configured to extract a particular portion from display information, which is displayed on a transparent display provided in a vehicle, based on a color-by-color pixel count of the display information. A display information output unit is configured to output to the transparent display the display information in which the particular portion extracted by the display information extracting unit has been changed in luminance.

TECHNICAL FIELD

The present invention relates to a display control device and a display control method. The present invention claims priority to Japanese Patent Application No. 2014-145633 filed on Jul. 16, 2014, the contents of which are incorporated herein by reference for the designated states where incorporation by reference of literature is allowed.

BACKGROUND ART

In Patent Literature 1, there is disclosed a “display device for a vehicle, including a background image obtaining unit configured to obtain a background image outside of a vehicle, a background image analyzing unit configured to analyze the background image, an information display area determining unit configured to determine an information display area, which is an area on a windshield, based on the result of analyzing the background image, an image signal generating unit configured to generate an image signal to be displayed in the information display area, and an image display unit configured to display the image signal on the windshield.”

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

A head-up display allows a user to see a scene ahead of the user through the display, and therefore has an advantage in that the user can visually recognize both of what is displayed on the display and a view ahead of the user. When too much information is being displayed, however, the user cannot see the view ahead well enough, which diminishes the advantage of being able to visually recognize both of information on the display and the view ahead.

The display device for vehicles of Patent Literature 1 is configured to analyze an image of the view ahead to display information in a place where an obstructed view does not cause problems for driving, such as the sky. In Patent Literature 1, however, where information is displayed varies depending on the view ahead, thus requiring the driver to constantly look out for where information is to be displayed. There is also a possibility that, in urban districts and other places that have many traffic signs and traffic lights, the view may be obstructed no matter what area is chosen to display information.

It is therefore an object of the present invention to provide a technology with which a drop in the visibility of display information is prevented while securing a clear view outside a vehicle.

Solution to Problem

This application includes a plurality of means for solving at least some of the problems described above, an example of which is as follows. In order to solve the above-mentioned problems, according to one embodiment of the present invention, there is provided a display control device, including: a display information extracting unit configured to extract a particular portion from display information, which is displayed on a transparent display provided in a vehicle, based on a color-by-color pixel count of the display information; and a display information output unit configured to output to the transparent display the display information in which the particular portion extracted by the display information extracting unit has been changed in luminance.

Advantageous Effects of Invention

According to the present invention, it is possible to prevent a drop in the visibility of the display information while securing a clear view outside the vehicle. Other objects, configurations, and effects than those described above are revealed through a description of embodiments given below.

DESCRIPTION OF EMBODIMENTS

First Embodiment

FIG. 1is a diagram for illustrating an example of the configuration of a display system to which a display control device according to a first embodiment of the present invention is applied. As illustrated inFIG. 1, the display system includes a display control device1, an input device2, a navigation device3, a transparent display4, and a non-transparent display5. The display system ofFIG. 1is installed in, for example, an automobile or other vehicles.

The input device2is operated by a user and receive an instruction issued through the operation. The input device2is configured to transmit the instruction issued through the user's operation to the navigation device3. The input device2is, for example, a button input device or a touch panel input device mounted on a display. The input device2may also be a gesture input device that uses a camera or an infrared sensor.

The navigation device3is configured to output to the display control device1a graphical user interface (GUI) that is a navigation screen mainly displaying a map, a screen for an audio player or other application programs, or the like. The navigation device3is also configured to output to the display control device1data of video or image contents that are handled by various application programs. The navigation device3includes an arithmetic device and a memory or other storage devices that are necessary to run a navigation program, a multimedia player, and other application programs.

The display control device1is connected to the navigation device3, the transparent display4, and the non-transparent display5. The display control device1is configured to composite pieces of image data output from, for example, the navigation device3, and to output the composite data to the transparent display4and the non-transparent display5.

The transparent display4is a display structured so that an image is projected onto a board of a glass element or other materials highly transmissive of visible light, and configured to display the image superimposed on an outside view. The transparent display4is provided in, for example, an automobile or other vehicles. More specifically, the transparent display4is a head-up display having a projection display board provided in front of the driver. Alternatively, the transparent display4may not have a projection display board and project an image directly onto the windshield in front of the driver. The transparent display4may instead be, for example, a glass-type head mounted display or other displays configured to display information superimposed on the user's (e.g., driver's) view.

The non-transparent display5is a liquid crystal display (LCD), an organic electroluminescence (EL) display, or other displays. The non-transparent display5is a display mounted on a center console which is generally called a center display or a navigation screen.

FIG. 2is a diagram for illustrating an example of functional blocks of the display control device. As illustrated inFIG. 2, the display control device1includes a display information input unit11, a display information extracting unit12, a display information processing unit13, a display information compositing unit14, and a display information output unit15.

The display information input unit11is configured to receive display information (image information) output from the navigation device3as input. The display information input unit11is configured to determine, from the output destination (the transparent display4and the non-transparent display5) and the property of the content of the input display information, whether or not the input display information is to be processed (data processing) by the display information processing unit13.

Examples of display information output from the navigation device3include GUI parts, text, and image contents. GUI parts are elements that make up a GUI in a display screen, for example, a button and a window frame. Text is the text data of address information for the navigation program, the text data of a tune title for the audio player, and other types of text data. Image contents are road traffic guide maps for the navigation program, icons for calling attention, jacket photos handled by the audio player, images obtained by a Web browser, and the like. The display information compositing unit14is configured to composite the pieces of information included in the display information, and output the composite information to the transparent display4and the non-transparent display5via the display information output unit15.

The display information extracting unit12is configured to extract a particular portion of display information based on the color-by-color pixel count of display information that is displayed on the transparent display4. The particular portion, which is described later, is, for example, the background portion of display information that is displayed on the transparent display4. The display information extracting unit12counts the number of pixels of the display information for each color separately, and extracts a portion in a color that has the highest pixel count as the particular portion.

The display information processing unit13is configured to change the luminance of the particular portion extracted by the display information extracting unit12. In other words, the display information processing unit13changes the luminance of the background portion of display information that is displayed on the transparent display4. For example, the display information processing unit13lowers the luminance of the particular portion when the luminance of a color of the display information that has the highest pixel count is higher than a given threshold. The display information processing unit13raises the luminances of other colors than the one having the highest pixel count when an average luminance of other colors of the display information than the one having the highest pixel count is lower than a given threshold.

The display information compositing unit14is configured to composite display information output from the display information input unit12. The display information compositing unit14is also configured to composite display information output from the display information processing unit13. The display information compositing unit14composites, for example, display information that is the GUI parts, text, and image contents described above.

The display information output unit15is configured to output display information composited by the display information compositing unit14to one of the transparent display4and the non-transparent display5that is specified as the output destination.

FIG. 3is a view for illustrating an example of a screen that is displayed on the non-transparent display. A screen21ofFIG. 3is an example of a screen that is displayed on the non-transparent display5. Display information that is output from the navigation device3to be displayed on the non-transparent display5is displayed on the non-transparent display5without undergoing data processing by the display control device1. For example, display information to be displayed on the non-transparent display5is input to the display information input unit11and output to the display information compositing unit14, instead of the display information extracting unit12, and then displayed on the non-transparent display5without undergoing luminance changing processing, which is described below.

FIG. 4is a view for illustrating an example of a screen that is displayed on the transparent display. InFIG. 4, (a part of) a windshield31of a vehicle is illustrated. The transparent display4is provided, for example, between the driver and the windshield31, which is in front of the driver. The transparent display4may be structured so that an image is projected directly onto the windshield31.

A screen32illustrated inFIG. 4is an example of a screen that is displayed on the transparent display4. As shown on the screen32, the transparent display4in the example ofFIG. 4displays text32a, which indicates the speed of the vehicle, and an image content32b, which represents a map.

A scene33indicated by the dotted lines ofFIG. 4represents a scene outside the vehicle that is viewed through the windshield31and the transparent display4.

An image34in a lower part ofFIG. 4represents display information (an image content) output from the navigation device3. An image35to the right of the image34is an image obtained by lowering the luminance of the background portion of the image34. InFIG. 4, a low luminance is represented by the color “black”, and the background portion of the image35(a black portion35a) is lower in luminance than the background portion of the image34(a gray portion34a). The transparent display4displays, instead of the image34output from the navigation device3, the image35, which is obtained by lowering the luminance of the background portion of the image34.

As described above, display information is input to the display information input unit11from the navigation device3. The display information input unit11determines whether the output destination of the input display information is the transparent display4or the non-transparent display5. The display information input unit11can use, for example, metadata included in the display information to determine the output destination of the input display information.

When determining that the non-transparent display5is the output destination of the input display information, the display information input unit11outputs the input display information to the display information compositing unit14so that the display information is subsequently output to the non-transparent display5. In other words, display information to be output to the non-transparent display5is output as it is to the non-transparent display5without undergoing data processing (a luminance change) executed by the display information processing unit13. The non-transparent display5thus displays, for example, the screen21illustrated inFIG. 3which is not changed in luminance.

When determining that the transparent display4is the output destination of the input display information, on the other hand, the display information input unit11determines whether or not the input display information is an image content. For example, the display information input unit11determines the speed displayed on the transparent display4ofFIG. 4(the text32a) as text. The display information input unit11determines the map displayed on the transparent display4ofFIG. 4(the image content32b) as an image content. The display information input unit11can use, for example, metadata included in the input display information to determine whether the input display information is a GUI part, text, or an image content.

When determining that the output destination of the input display information is the transparent display4and that the input display information is an image content, the display information input unit11outputs the display information to the display information extracting unit12. The display information extracting unit12extracts the background portion of the display information (image content) output from the display information input unit11. The display information processing unit13then lowers the luminance of the background portion extracted by the display information extracting unit12.

In the case where the input display information has the transparent display4as its output destination but is not an image content (is a GUI part or text), the display information input unit11outputs the input display information to the display information compositing unit14.

The background of an image content is, for example, a portion of the image content that has no information. For example, the background of an image content is a portion of the image content32bofFIG. 4that is not a character or a mark, and corresponds to the gray portion of the image34or the black portion of the image35.

Information displayed on the transparent display4is fainter and the transmittance of the transparent display4is higher when the luminance of an image projected onto the transparent display4is lower. Conversely, information displayed on the transparent display4is clearer and the transmittance of the transparent display4is poorer when the luminance is higher.

The lowered luminance of the background portion of an image content therefore gives the driver higher visibility of a scene on which the background of the image content is superimposed. For example, the display information processing unit13lowers the luminance of the background portion of the image34, which is output from the navigation device3, as in the image35ofFIG. 4. This improves the visibility of the scene33on which the image content32bis superimposed.

The display information extracting unit12extracts the background portion of an image content displayed on the transparent display4, based on the color-by-color pixel count of the image content. For example, the display information extracting unit12counts the number of pixels of the image content for each color separately, and extracts a portion that has the highest pixel count as the background portion.

A portion in a color that has the highest pixel count is thus extracted as the background portion because a portion in a color that has the highest pixel count can be deemed as the background portion of an image content. For example, the background portions of image contents except photographs are unicolored in general, and are considered to take up the largest areas in the image contents. A more specific example is found in the image34ofFIG. 4in which the gray portion (the background portion of the image content) has the largest areal dimensions and is often expressed in one color.

However, a background that is made up of a plurality of similar colors such as gradation colors cannot be extracted by the method described above. Then, the display information extracting unit12may use a given significant bit of color information to classify colors and count colors that are close to one another (colors that have the same figure as the significant bit) as the same color.

While the transmittance of the transparent display4can be raised by lowering the luminance of an image, a drop in luminance leads to a drop in the visibility of display information in reverse proportion to the rise in the transmittance of the transparent display4. A portion of an image where a drop in the visibility with the lowered luminance causes no problems and a portion of the image where a drop in the visibility with the lowered luminance causes problems are therefore separately adjusted in luminance.

A unicolored background is often set to an image content intended to convey information via characters or graphic forms. In addition, it is considered that the lack of the background portion affects an image content little in terms of conveying information. The display information processing unit13therefore selectively lowers the luminance of the background portion of an image content that is extracted by the display information extracting unit12. GUI parts and text, on the other hand, contain information that the driver is to be aware of, and are output by the display information input unit11to the display information compositing unit14, instead of the display information extracting unit12, to avoid undergoing luminance changing processing.

FIG. 5is a flow chart for illustrating an example of the operation of the display control device. The display control device1executes processing illustrated in the flow chart ofFIG. 3when display information is output from the navigation device3.

The display information input unit11first determines which of the transparent display4and the non-transparent display5is the output destination of the display information output from the navigation device3(Step S1). For example, the display information input unit11determines the output destination of the display information output from the navigation device3, based on metadata that is included in the display information and that indicates whether this display information is to be output to the transparent display4or the non-transparent display5. When the display information input unit11determines that the transparent display4is the output destination of the display information output from the navigation device3(“YES” in Step S1), the processing proceeds to Step S2. When the display information input unit11determines that the non-transparent display5is the output destination of the display information output from the navigation device3(“NO” in Step S1), the processing proceeds to Step S8.

In the case where the non-transparent display5is the output destination of the display information, the display information is composited as it is by the display information compositing unit14irrespective of the property of the display information, that is, whether the display information is a GUI part, text, or an image content, and the composited information is displayed on the non-transparent display5. In other words, when the display information input unit11determines that the output destination of the display information is the non-transparent display5, the processing proceeds to Step S8so that data processing of Step S5, which is described below, is not executed.

When determining in Step S1that the transparent display4is the output destination of the display information output from the navigation device3, the display information input unit11determines whether or not the display information is an image content (Step S2). When the display information input unit11determines that the display information output from the navigation device3is an image content (“YES” in Step S2), the processing proceeds to Step S3. When the display information input unit11determines that the display information output from the navigation device3is not an image content, for example, when the display information is determined as a GUI part or text (“NO” in Step S2), the processing proceeds to Step S8.

In short, when display information is an image content and has the transparent display4as its output destination, the data processing of Step S5described below is performed on the display information (an image content). When display information has the transparent display4as its output destination but is a GUI part and text, the data processing described below is not executed for the display information (a GUI part and text). The processing proceeds to Step S8in this case.

An appropriate shape, color, and size of a GUI part are determined in advance for each display separately. A GUI part that is output to the transparent display4accordingly has a color and a size that are determined in advance by taking the visibility on the transparent display4into consideration. The display control device1therefore outputs input information that is a GUI part as it is without executing size processing.

In the case where the display information input unit11determines in Step S2that the display information output from the navigation device3is an image content (“YES” in Step S2), the display information extracting unit12counts the number of pixels of the image content for each color separately, and extracts a color in the image content that has the highest pixel count (Step S3).

Next, the display information processing unit13determines whether or not the luminance of the color extracted in Step S3is higher than a given threshold (Step S4). The luminance may be calculated by using the value of one of R, G, and B as it is. Desirably, however, the luminance is calculated by weighting the R value, the G value, and the B value each with a certain weight and then obtaining a weighted average. When the display information processing unit13determines that the luminance of the extracted color is not higher than the given threshold (“NO” in Step S4), the processing proceeds to Step S8. When the display information processing unit13determines that the luminance of the extracted color is higher than the given threshold (“YES” in Step S4), the processing proceeds to Step S5.

When determining in Step S4that the luminance of the extracted color is higher than the given threshold, the display information processing unit13lowers the luminance of the pixel of the extracted color (Step S5).

The threshold that is a reference for determining whether to lower the luminance is determined by to what extent the driver's view ahead is obstructed when the image content is projected onto the transparent display4. For example, the threshold is set to 30% of the maximum luminance in the case where the display has a transmittance of 0% at the maximum luminance and a transmittance of 50% at a luminance that is 50% of the maximum luminance, and a transmittance of 70% is to be secured in the background portion of the image content. The relationship between the luminance and transmittance of a transparent display varies from one display to another. The threshold is therefore set to a value that secures a satisfactory transmittance for the particular display when an image is projected at that luminance.

The changed luminance may be equal to the threshold used in the determination of Step S4, or may be 0% (black). When the luminance is changed to black, the transmittance becomes 100% but the original background color of the image content is completely lost. This can be avoided by changing the luminance to a value that is greater than 0% and that does not exceed the threshold. The significantly lowered luminance makes the boundary between the image content and the rest portions indistinct on the display screen, and may deteriorate the visibility of the image content. In this case, the perimeter of the image content may be outlined in a color that has a high luminance.

Next, the display information processing unit13determines whether or not an average luminance value of other portions of the image content than the background portion is lower than a given threshold (Step S6). When the display information processing unit13determines that the average luminance value of other portions of the image content than the background portion is lower than the given threshold (“YES” in Step S6), the processing proceeds to Step S7. When the display information processing unit13determines that the average luminance value of other portions of the image content than the background portion is not lower than the given threshold (“NO” in Step S6), the processing proceeds to Step S8.

When determining in Step S6that the average luminance value of other portions of the image content than the background portion is lower than the given threshold, the display information processing unit13raises the luminances of other portions of the image content than the background portion (Step S7).

Step S7is executed because, when central portions of the image content (other portions than the background portion, for example, an arrow indicating the traveling direction and characters spelling the name of a place) are low in luminance, the processing of lowering the luminance of the background portion in Step S5lowers the overall luminance of the image, thereby deteriorating the visibility of the other portions than the background portion. In order to prevent this situation, the display information processing unit13executes processing of raising the luminances of central portions of the image content when the luminances of the central portions are equal to or lower than a certain level.

The threshold that is a reference for determining whether to raise the luminance in Step S6is determined by whether the other portions than the background portion can visibly be recognized well when the image is projected onto the transparent display4. For example, the threshold that is a reference for the determination of Step S6is set around 70% of the maximum luminance. The changed luminance may be equal to the threshold or may be a value higher than the threshold. The display information processing unit13raises the luminance of each pixel that is in other portions than the background portion by, for example, 20% when the average luminance of the other portions than the background portion is 50% and the threshold is set to 70%. The raised luminance increases visibility but makes all colors close to white, thereby making the image lose its original colors. It is therefore desirable to set the luminance to an appropriate value.

FIG. 6is a diagram for illustrating an example of the hardware configuration of the display control device. The display control device1may implement the functions illustrated inFIG. 2with, for example, pieces of hardware illustrated inFIG. 6. The pieces of hardware include an arithmetic device41, which is a central processing unit (CPU) or the like, a main storage device42, which is a random access memory (RAM) or the like, an auxiliary storage device43, which is an HDD or the like, a communication interface (I/F)44configured to establish wired or wireless connection to a communication network, and a read/write device45configured to read/write information on a digital versatile disk (DVD) or other portable recording media.

The given program may instead be installed from, for example, a recording medium read by the read/write device45, or from a network via the communication I/F44.

In this manner, the display information extracting unit12of the display control device1extracts a particular portion of display information to be displayed on the transparent display4, which is provided in the windshield of a vehicle, based on the number of pixels of the display information that is counted for each pixel separately. The display information output unit15outputs to the transparent display4the display information in which the luminance of the particular portion extracted by the display information extracting unit12has been changed. The display control device1can thus prevent a drop in the visibility of display information while securing a clear view outside of the vehicle.

The display information processing unit13changes the luminance of the particular portion extracted by the display information extracting unit. This enables the display control device1to avoid obstructing a view ahead without changing where display information is displayed.

The display information processing unit13lowers the luminance of the particular portion when the luminance of a color of the display information that has the highest pixel count is higher than a given threshold. This allows the display control device1to reduce power consumption by omitting the luminance changing processing in the case of, for example, display information that has a low luminance in the particular portion in the first place.

The display information processing unit13raises the luminances of other colors of the display information than the color that has the highest pixel count when an average luminance value of the other colors than the color having the highest pixel count is lower than a given threshold. This enhances the visibility of information that is displayed in other portions than the background portion, for example, information that the driver is to be aware of.

The display control device1and the navigation device3, which are separate devices in the drawings, may be configured as a single device. For example, the display control device1and the navigation device3may share an arithmetic processing device and a memory to be configured as a single device.

Second Embodiment

An example of varying the display format between different displays is described in a second embodiment of the present invention. In the example of the second embodiment, a different screen is displayed on each of a plurality of displays connected to a display control device, by varying the layer to be output and the luminance from one display to another. The description of the second embodiment deals with differences from the first embodiment.

FIG. 7is a diagram for illustrating an example of the configuration of a display system to which the display control device according to the second embodiment is applied. InFIG. 7, components that are the same as those ofFIG. 1are denoted by the same reference symbols. A non-transparent display52is connected to a display control device51in the display system ofFIG. 7.

The non-transparent display52is, for example, a display provided inside a meter which is called a meter display. Being provided inside a meter, a meter display has a small display area. In many meter displays, the luminance of the background is often set low while the luminance of a displayed graphic form or character is set high, to match the way a meter displays information.

FIG. 8is a diagram for illustrating an example of functional blocks of the display control device. InFIG. 8, components that are the same as those ofFIG. 2are denoted by the same reference symbols. The display control device51ofFIG. 8includes a control input unit61, a layer information management unit62, and a display information compositing unit63. The display control device51does not include the display information processing unit13, which is included in the display control device1illustrated inFIG. 2.

The control input unit61is configured to control the layer information management unit62. For example, the control input unit61uses a control signal from the navigation device3to control layer management information, which is managed by the layer information management unit62. The control input unit61is also configured to output to the layer information management unit62information that is input to the input device2by a user when the user operates the input device2to change whether or not a layer screen is to be displayed or a color used in display.

The layer information management unit62is configured to manage a layer management table in which display's information about a display to which display information is output, the size of the display, layer information that indicates layers of the display information to be output to the display, and a color conversion rule that lays down a color conversion regulation for each layer are stored in association with one another.

The display information compositing unit63is configured to convert a color of a layer by referring to the color conversion rule of the layer management table, and to composite layers of display information to be output to a display by referring to the layer information of the layer management table. When compositing layers, the display information compositing unit63converts the layers into a given size by referring to the layer management table.

The functions of the control input unit61, the layer information management unit62, and the display information compositing unit63are implemented by the arithmetic device41by executing a given program that is loaded onto the main storage device42from the auxiliary storage device43or from other places.

FIG. 9is a view for illustrating an example of screens that are displayed on the respective displays. A screen71illustrated inFIG. 9is an example of a screen that is displayed on the non-transparent display5, which is a center display or the like. A screen72is an example of a screen that is displayed on the transparent display4, which is a head-up display or the like. A screen73is an example of a screen that is displayed on the non-transparent display52, which is a meter display or the like. The screens71to73display a map containing the location of the vehicle, the current time, the estimated time of arrival, the direction, and the scale.

The screen71displayed on the non-transparent display5is displayed without being processed (changed in luminance) by the display control device51.

The screen72displayed on the transparent display4is displayed after setting the luminance of the background portion lower and the luminances of other portions than the background portion higher than in the screen71, which is displayed on the non-transparent display5. In short, the screen72displayed on the transparent display4is displayed after being processed by the display control device51.

The screen73displayed on the non-transparent display is displayed without detailed information (for example, information indicating narrow streets and information indicating route numbers) that is found on the screen71, which is displayed on the non-transparent display5. The screen73displayed on the non-transparent display52is displayed after setting the luminance of the background portion lower and the luminances of other portions than the background portion higher than in the screen71, which is displayed on the non-transparent displays. In short, the screen73displayed on the non-transparent display52is displayed after being processed by the display control device51.

The display control device51executes drawing and color conversion on a layer-by-layer basis in order to vary the display format from one display to another as shown on the screens71to73. Layer-by-layer drawing is a method in which one piece of display information is divided into several layers, and layers to be output are switched suitably depending on to which display the display information is output.

The layers include, for example, a basic layer, a detailed layer, and a background layer each having different information. The display control device51superimposes given layers, which are determined for each display separately, on top of one another and outputs the layers to the display.

FIG. 10is Diagram1for illustrating layers. An image81illustrated inFIG. 10is an example of an image of the basic layer. An image82is an example of an image of the detailed layer. An image83is an example of an image of the background layer.

In the case of display information that is output to the transparent display4, for example, the display control device51composites the images81to83of all layers, and outputs the composite image to the transparent display4. The display control device51composites the images81to83of all layers also when display information is output to the non-transparent display5, and outputs the composite image to the transparent display4. An image84ofFIG. 10is an example of an image that is obtained by compositing the images81to83of the respective layers.

In the case of display information that is output to the non-transparent display52, on the other hand, the display control device51composites the images81and83of some of the layers, and outputs the composite image to the non-transparent display52. For example, in the case of display information to be output to the non-transparent display52, the display control device51outputs an image that is obtained by compositing the image81and the image82to the non-transparent display52.

Information allocated to the basic layer is a portion of display information that is high in importance. For example, GUI parts, text, image contents of arterial roads and the like, and vehicle location information are allocated to the basic layer.

Information allocated to the detailed layer is one that supplements information allocated to the basic layer. For example, images of detailed road information such as narrow streets are allocated to the detailed layer.

The background layer is allocated a background image.

FIG. 11is Diagram2for illustrating layers. An image91illustrated inFIG. 11is an example of an image of the basic layer. Image contents, for example, arterial roads and vehicle location information, are displayed in the image91.

An image92is another example of an image of the basic layer. A GUI part and text, for example, characters and a window frame, are displayed in the image92.

An image93is an example of an image of the detailed layer. An image content of information that supplements information of the basic layer, for example, narrow streets, is displayed in the image93.

An image94is an example of an image of the background layer. An image content, for example, a unicolored image, is displayed in the image94.

FIG. 12is a diagram for illustrating an example of the data configuration of the table that is included in the layer information management unit. The layer information management unit62includes a layer management table101as the one illustrated inFIG. 12. The layer management table101includes a “display's information” field, a “size” field, a “layer information” field, and a “color conversion rule” field. The layer management table101is stored in, for example, the main storage device42illustrated inFIG. 6.

The name of a display connected to the display control device51is stored in the “display's information” field. For example, “center display” ofFIG. 12is the name of the non-transparent display5, “meter display” is the name of the non-transparent display52, and “head-up display” is the name of the transparent display4. While the name of a display is written in the “display's information” field in the exampleFIG. 12for the conveniences of description, the displays are managed in practice by assigning a unique ID or the like to each display.

The size of the display connected to the display control device51is stored in the “size” field. The size of a display is expressed in, for example, pixels. The display information compositing unit63converts images of the respective layers that are output from the navigation device3into a size written in the “size” field. For example, the display information compositing unit63converts an image of a layer to be output to the “meter display” into a size “400×300” based on information stored in the “size” field in association with the “meter display”.

Information of layers to be output to the display is stored in the “layer information” field. The display information compositing unit63composites layers of display information output from the navigation device3, based on the information stored in the “layer information” field.

In the case where the navigation device3outputs the images91to94of layers which are illustrated inFIG. 11, for example, the display information compositing unit63composites the images91and92of the basic layer, the image93of the detailed layer, and the image94of the background layer for the “center display”, based on information stored in the “layer information” field in association with the “center display”. This produces, for example, image data of the screen71illustrated inFIG. 9.

The display information compositing unit63composites the images91and92of the basic layer and the image94of the background layer for the “meter display”, based on information stored in the “layer information” field in association with the “meter display”. This produces, for example, image data of the screen73illustrated inFIG. 9.

The display information compositing unit63composites the images91and92of the basic layer, the image93of the detailed layer, and the image94of the background layer for the “head-up display”, based on information stored in the “layer information” field in association with the “head-up display”. This produces, for example, image data of the screen72illustrated inFIG. 9.

While names are written in the “layer information” field in the example ofFIG. 12for the conveniences of description, the layers are managed in practice by assigning a unique ID or the like to each layer.

A color conversion rule applied when display information is output to the display is stored in the “color conversion rule” field. The color conversion rule is defined for each layer separately. The display information compositing unit63performs color conversion on each layer of display information output from the navigation device3, based on information stored in the “color conversion rule” field.

For example, the display information compositing unit63composites images of the respective layers without converting the colors of the layers for the “center display”, based on information stored in the “color conversion rule” field in association with the “center display”. As a result, the “center display” displays, for example, a background along with a map, text, and a GUI part as in the screen71ofFIG. 9.

For the “meter display”, the display information compositing unit63composites images by raising the luminances of R, G, and B in the basic layer by 20% and lowering the luminances of R, G, and B in the background layer by 20%, based on information stored in the “color conversion rule” field in association with the “meter display”. This gives the meter display a dark background, for example, as in the screen73ofFIG. 9.

For the “head-up display”, the display information compositing unit63composites images by raising the luminances of R, G, and B in the basic layer and the detailed layer by 20% and lowering the luminances of R, G, and B in the background layer by 20%, based on information stored in the “color conversion rule” field in association with the “head-up display”. This increases the transmittance of the background on the head-up display and improves the visibility of a scene as in the screen72ofFIG. 9, for example.

Colors based on information stored in the “color conversion rule” field of the layer management table101are specified for each layer, and are output to the relevant display. Accordingly, the same display information is expressed in different colors when output destinations having different color conversion rules are specified.

For example, no color conversion rule is defined for the center display in the example ofFIG. 12, which indicates that color conversion is not executed. No color conversion rule is defined for the center display because, unlike the head-up display, the center display does not need to change the background color. In such cases where a color change is not executed at the time of display, color conversion rules do not need to be defined.

The head-up display, on the other hand, has a color conversion rule defined therefor. The color conversion rule set to the head-up display in the example ofFIG. 12dictates raising the luminances of the basic layer and the detailed layer and lowering the luminance of the background layer in a manner that suits the characteristics of the head-up display.

In short, while the same information (the same layers) is displayed on the center display and the head-up display, the information is displayed in different colors on the center display and the head-up display due to the color conversion rule.

The color conversion rules in the example ofFIG. 12are provided for the conveniences of description, and an actual color conversion rule defines, for each of the R value, the G value, and the B value, what conversion formula is to be applied. Alternatively, color conversion rules may be defined in the form of a color palette or other forms that directly determine a post-conversion color for each color.

While changing the luminance of each color uniformly is defined in the example ofFIG. 12, a rule dictating the use of colors that are enhanced in green hue over the entire screen may be defined for the head-up display, which is said to be high in the visibility of information displayed in green as well as white. A plurality of color conversion rules may be defined to switch from one rule to another depending on the situation, in order to accommodate the fact that how the luminance affects the visibility of a display is varied by a difference in ambient brightness between night and day, or the like. For example, two layer management tables101, one for day and one for night, are prepared. The navigation device3outputs an instruction about which of the day layer management table101and the night layer management table101is to be used. The control input unit61follows the instruction from the navigation device3in switching the layer management table101to be used.

FIG. 13is a flow chart for illustrating an example of the operation of the display control device. The display control device51executes processing illustrated in the flowchart ofFIG. 13when display information is output from the navigation device3.

Display information that is an alert or for calling attention is, for example, a graphic form for warning the driver of a bump into a vehicle ahead of the driver, and is made up of an icon or characters. The navigation device3specifies a color that is likely to attract the attention of the driver or others, for example, red, yellow, or, orange, for display information that is an alert or for calling attention. When the display information input unit11determines that the navigation device3has output display information that is an alert or for calling attention, the processing proceeds to Step S16, which is described below, so that the color specified by the navigation device3is not changed.

When determining in Step S11that the display information output from the navigation device3is not the display information that is an alert or for calling attention, the display information input unit11determines whether or not the display information is an image content (Step S12). When the display information input unit11determines that the display information output from the navigation device3is an image content (“YES” in Step S12), the processing proceeds to Step S13. When the display information input unit11determines that the display information output from the navigation device3is not an image content, for example, when the display information is determined as a GUI part or text (“NO” in Step S12), the processing proceeds to Step S15.

When determining in Step S12that the display information output from the navigation device3is an image content, the display information input unit11determines whether or not the image content output from the navigation device3includes the background layer (Step S13). The display information input unit11uses, for example, metadata that is included in the image content output from the navigation device3to determine whether or not the background layer is included.

Whether the image content includes the background layer or not is determined because, while an image content that is generated and output by the navigation device3is divided into the basic layer, the detailed layer, and the background layer, some image contents of traffic jam information or traffic restriction information distributed from a traffic information system (image contents distributed from a traffic information system, received by the navigation device3, and output to the display information input unit11) are not divided into the basic layer, the detailed layer, and the background layer. For that reason, the display information input unit11determines whether or not the image content output from the navigation device3includes the background layer. When the display information input unit11determines that the display information output from the navigation device3includes the background layer (“YES” in Step S13), the processing proceeds to Step S15. When the display information input unit11determines that the display information output from the navigation device3does not include the background layer (“NO” in Step S13), the processing proceeds to Step S14.

When the display information input unit11determines in Step S13that the display information output from the navigation device3does not include the background layer, the display information extracting unit12extracts the background portion of the image content, and sets the extracted portion as the background layer (Step S14). The display information extracting unit12extracts the background portion of the image content by, for example, the same processing that is executed in Step S3ofFIG. 5(by counting the number of pixels for each color separately). The display information extracting unit12sets an image of the extracted background portion as the background layer, and sets images of other portions than the background portion as, for example, the basic layer.

When the display information input unit11determines in Step S12that the display information is not an image content, or when the display information input unit11determines in Step S13that the background layer is included, or when the display information extracting unit12executes in Step S14the processing of setting the background layer, the display information compositing unit14performs color conversion on the display information by referring to the “color conversion rule” field of the layer management table101(Step S15). For example, the display information compositing unit14executes color conversion for each layer by referring to the “color conversion rule” field of the layer management table101, based on to which display the display information is output.

When the display information input unit11determines in Step S1that the display information output from the navigation device3is display information that is an alert or for calling attention, or when the display information compositing unit14executes in Step S15the color conversion of the display information, the display information compositing unit14determines, for each layer, whether or not the size of the layer is larger than the size of the relevant display (Step S16). For example, for each display that is the output destination of the display information, the display information compositing unit14refers to the “size” field of the layer management table101to determine whether or not the size of the received display information that is an alert or the like, or the size of the color-converted display information, is larger than the size of the display. When the display information compositing unit14determines that the display information that is an alert or the like, or the color-converted display information, is larger in size than the display (“YES” in Step S16), the processing proceeds to Step S17. When the display information compositing unit14determines that the display information that indicates how an alert or the like is displayed, or the color-converted display information, is not larger in size than the display (“NO” in Step S16), the processing proceeds to Step S18.

When determining in Step S16that the size of the display information is larger than the size of the display, the display information compositing unit14refers to the “size” field of the layer management table101and reduces the size of the display information (Step S17). For example, the display information compositing unit14executes reduction conversion while maintaining the aspect ratio so that the display information is contained within the display area of the display.

In the example of the layer management table101ofFIG. 12, the meter display is set to a size smaller than the sizes of the other displays. A navigation screen that is tailored to the size of the center display undergoes reduction conversion in Step S17in the case where the navigation screen is to be displayed on the meter display.

When determining in Step S16that the size of the display information is not larger than the size of the display, or when executing the processing of reducing the display information in Step S17, the display information compositing unit14refers to the “layer information” field of the layer management table101and composites the layers of the display information (Step S18).

The navigation device3may prepare the background as separate data. In this case, the prepared background image is specified as the background layer in advance. Display information for which the background layer is specified in this manner can skip Step S13in which whether or not the background layer is included is determined and the separation processing of Step S14.

In this manner, the layer management table101of the display control device51stores display's information about a display to which display information is output, layer information that indicates layers of the display information to be output to the display, and a color conversion rule that lays down a color conversion regulation for each layer in association with one another. The display information compositing unit63refers to the color conversion rules of the layer management table101to convert the colors of the layers, and refers to the layer information of the layer management table101to composite the layers of pieces of display information that is output to the transparent display4and the non-transparent displays5and52. This enables the display control device51to vary the display format between different displays.

In the case where the background layer is not included in display information output from the navigation device3, the display information extracting unit12extracts a particular portion of the display information as the background layer. This enables the display control device51to vary the display format even when display information output from the navigation device3is not divided into the background layer and other layers.

The display information compositing unit63does not change the luminance of a color in the background layer of display information in the case where the display information is an alert or other specific types of information. This enables the display control device51to maintain the visibility of an alert or other specific types of information.

The present invention is not limited to the embodiments described above. The present invention includes various modified examples. For example, the embodiments described above are described in detail in order to facilitate an understanding of the present invention. The present invention is not necessarily limited to the one including all of the configurations described above.

Further, a part of the configurations of a given embodiment may be replaced with the configurations of another embodiment. Alternatively, the configurations of a given embodiment may be added to the configurations of another embodiment. For example, Step S11of the second embodiment illustrated inFIG. 13may be executed in the first embodiment. The information processing unit13of the first embodiment holds back from changing the luminance of the particular portion when display information output from the navigation device3is display information that is an alert or for calling attention. In addition, other configurations may be added to, deleted from, or replace a part of the configurations of each embodiment.

Further, each of the above-mentioned configurations, functions, processing units, processing steps, and the like may be realized by hardware by, for example, designing all or some of such configurations, functions, processing units, and processing steps as integrated circuits, for example.

Further, only control lines and information lines thought to be necessary for description are illustrated. Not all of the control lines and information lines in a product are illustrated. In an actual product, it may be considered that almost all parts are connected to each other.

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