JP2004078075A - On-screen display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-screen display device capable of reducing a data transfer amount. <P>SOLUTION: An OSD circuit 100 is provided with a memory 112 for previously storing substituent bit map data 110 for substituting for part of bit map data 102 transferred from an SDRAM 20 to enable the bit mpa data 102 transferred from the SDRAM 20 and the bit map data 110 stored in the memory 112 to be switched by a selector 142 at an arbitrary coordinate position (H, V) and outputted. Consequently, some of characters are changed, the need to rewrite the bit map data 102 in the SDRAM 20 is eliminated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an on-screen display device, and more particularly to an on-screen display device that superimposes and displays an image based on sub-image data read from a predetermined storage unit on an image based on main image data.
[0002]
[Prior art]
Conventionally, in digital cameras such as digital still cameras and digital video cameras, a liquid crystal display (LCD) is formed by superimposing characters and other characters as images based on sub-image data on subject images as images based on main image data. Some of them have an OSD (On Screen Display) function for displaying them on a display means. As a display method using the OSD function, a method called “character generation” that displays character data stored in a ROM and a bitmap method that handles characters like image data are known. In the case of bitmap display, bitmap data representing a character to be superimposed is placed on a predetermined memory provided separately from the OSD circuit, for example, a main memory, and DMA transfer from the memory to the OSD circuit is performed. (See JP-A-9-205597 and JP-A-11-212539).
[0003]
[Problems to be solved by the invention]
However, in the prior art, even when only a part of the character to be superimposed is changed, it is necessary to rewrite the bitmap data on the main storage device. For example, in order to notify the zoom position during shooting to the user, When a character including a mark indicating the position (photographing magnification) is displayed in a superimposed manner while changing the mark in accordance with the zoom position change, the character on the main storage device must be frequently rewritten and used for data transfer. As a result, bus traffic increases, and as a result, there is a problem that data transfer from the main storage device to the OSD circuit is not in time, display is disturbed, and processing speed of other functions is reduced.
[0004]
The present invention has been made to solve the above problems, and an object thereof is to provide an on-screen display device capable of reducing the amount of data transfer.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an on-screen display device that superimposes and displays an image based on sub-image data read from a predetermined storage means on an image based on main image data. A replacement image data storage means for storing replacement image data for replacement with a part of the sub image data, and a part of the sub image data is stored in the replacement image data storage means. Replacement means for replacing with the replacement image data.
[0006]
According to the first aspect of the present invention, when the sub image data is read out from the predetermined storage unit and the image based on the sub image data is superimposed and displayed on the image based on the main image data, the replacement unit performs the predetermined process. A part of the sub image data read from the storage means can be replaced with the replacement image data stored in the replacement image data storage means.
[0007]
That is, when a part of the image based on the sub-image data is frequently changed, image data indicating the changed state of the changed portion is used as replacement image data storage means as replacement image data. If it is stored in, without rewriting the sub image data stored in the predetermined storage means, the data at the position corresponding to the changed portion of the sub image data is replaced with the replacement image data, A part of the image based on the sub-image data can be changed. Thereby, when changing a part of the image based on the sub image data, it is not necessary to rewrite the sub image data on the predetermined storage means, and the data transfer required for the rewriting to the predetermined storage means is performed. Therefore, the amount of data transfer can be reduced.
[0008]
According to a second aspect of the present invention, in the first aspect of the invention, the replacement unit determines a replacement position on the sub image data based on setting information input from the outside. .
[0009]
According to the second aspect of the present invention, the replacement unit determines a replacement position on the sub image data when replacing the sub image data and the replacement image data based on setting information input from the outside. Then, a part of the sub image data is replaced with the replacement image data.
That is, the replacement position can be arbitrarily changed by setting information from the outside.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an example of an embodiment according to the present invention will be described in detail with reference to the drawings. In the following, the case where the on-screen display device of the present invention is applied to a digital still camera will be described. However, the present invention includes display means such as a digital video camera and a television device in addition to the digital still camera. Any device can be applied.
[0011]
As shown in FIG. 1, a digital still camera (hereinafter referred to as a digital camera) 10 according to the present embodiment includes an optical unit 12 including a lens for forming a subject image, and an optical unit 12. A CCD (Charge Coupled Device) 14 disposed behind the optical axis, an LCD 16 for displaying images and various information obtained by photographing with the digital camera 10, and an operating means 18 operated by the photographer. An SDRAM 20 as a main storage device that temporarily stores digital image data 48 obtained mainly by photographing with the CCD 14, an external ROM 22 in which various programs, parameters, and the like are stored in advance, and a main control that controls the operation of the entire digital camera 10. And a portion 24.
[0012]
Note that the operation unit 18 is a shooting operated to select any one of a release button, a still image shooting mode, a moving image shooting mode, and a playback mode that are operated when instructing execution of still image or moving image shooting. A mode selector as a mode selection means, various parameters are set, a cursor button operated to specify an image to be reproduced when the reproduction mode is selected, and an operation to turn on / off the power of the digital camera 10 Power switch.
[0013]
The main control unit 24 also includes an A / D converter 30 that converts an analog signal into a digital signal, an A / F control circuit 32 that adjusts the optical zoom magnification and focus of the optical unit 12, and an LCD that displays an image on the LCD 16. For transmitting / receiving various data to / from the drive circuit 34, a memory control circuit 36 for controlling reading / writing of data to / from the SDRAM 20, and the PC 70 as an external device connected to the digital camera 10 via a predetermined cable such as a USB cable. An image composed of an image processing circuit and a CPU 44A (see FIG. 2) in which a communication control circuit 40 and a media control circuit 42 for controlling reading and writing of various data with respect to the recording medium 72 perform various processes on the input digital signal. It is configured to be connected to the processing unit 44. The image processing unit 44 controls the overall operation of the digital camera 10, grasps the operation status of the operation means 18 by the photographer, and operates the respective units of the main control unit 24 according to the grasped operation status. To control.
[0014]
In the present embodiment, the main control unit 24 is configured as a one-chip LSI (Large Scale Integrated circuit), thereby reducing the size, high reliability, and cost of the digital camera 10. ing.
[0015]
The optical unit 12 includes a zoom lens group and a focus lens (not shown), and includes a lens moving mechanism that moves them in the optical axis direction, and is configured as a zoom lens that can change (magnify) the focal length. .
[0016]
The optical unit 12 is connected to an A / F control circuit 32. Under the control of the A / F control circuit 32, the zoom lens group is moved in the optical axis direction so as to achieve a desired zoom magnification (focal length variable lens). ), The focus lens is moved in the optical axis direction (autofocus (AF) mechanism) so that the incident light indicating the subject image that has passed through the lens is formed on the light receiving surface of the CCD 14. As a result, the CCD 14 captures the subject based on the incident light indicating the subject image that has passed through the lens of the optical unit 12 and outputs an analog image signal indicating the subject image.
[0017]
In the present embodiment, as the focus control, a so-called TTL (Through The Lens) system that adjusts the lens position so that the contrast of an image obtained by shooting is maximized is adopted, and the focus is controlled within the shooting area. In-focus control is automatically performed so that a subject existing at a predetermined position (AF frame) is in focus. Specifically, when a still image shooting mode for shooting a still image is selected by the operation of the mode change switch of the operation means 18 by the photographer, the release button is pressed halfway to automatically In-focus control is performed. On the other hand, when a moving image shooting mode for shooting a moving image is selected, after the release button is fully pressed and shooting is started, focus control is continuously performed.
[0018]
The output end of the CCD 14 is connected to the A / D converter 30. That is, the A / D converter 30 converts an analog image signal indicating a subject image photographed and output by the CCD 14 into a digital image signal. The output end of the A / D converter 30 is connected to the image processing unit 44. In other words, the image signal indicating the subject image obtained by the CCD 14 at the time of shooting is converted from an analog signal to a digital signal and then input to the image processing unit 44 and handled as digital image data.
[0019]
The image processing unit 44 performs white balance adjustment on the input digital image data by applying a digital gain corresponding to the light source type, and performs gamma processing and sharpness processing to generate predetermined digital image data 48. Further, YC conversion processing is performed to generate luminance data Y and chroma data Cr and Cb (hereinafter referred to as “YC data”). The YC data is converted into digital image data 48 representing a subject image via the memory control circuit 36. And once stored in the SDRAM 20.
[0020]
The digital image data 48 stored in the SDRAM 20 is read out by the image processing unit 44 through the memory control circuit 36, compressed by a compression / decompression circuit (not shown) by a predetermined compression method such as JPEG, and then recorded on the recording medium. The data is input to the I / F 60 and recorded on the recording medium 72 loaded in the digital camera 10.
[0021]
The recording medium 72 can be in various forms such as smart media, PC cart, micro drive, multimedia card (MMC), magnetic disk, optical disk, magneto-optical disk, memory stick, etc. Corresponding signal processing means and interfaces are applied.
[0022]
The digital image data 48 stored in the SDRAM 20 is read by the image processing unit 44 via the memory control circuit 36 and input to the LCD drive circuit 34.
[0023]
The LCD drive circuit 34 includes a video encoder 50, and converts the input digital image data 48 (YC signal) to an NTSC (National TV Standards Committee) signal. The LCD drive circuit 34 is connected to the LCD 16, and supplies the converted NTSC signal to the LCD 16, thereby causing the LCD 16 to display an image based on the digital image data 48.
[0024]
Further, the digital image data 48 is periodically rewritten by the image signal output from the CCD 14 and a video signal generated from the digital image data 48 is supplied to the LCD 16, so that the subject image captured by the CCD 14 can be obtained in substantially real time. It is displayed on the LCD 16 as a moving image or as a continuous image. That is, the LCD 16 can be used as an electronic viewfinder, and the photographer can check the shooting angle of view not only with a normal optical viewfinder (not shown) but also with a display image (so-called through image) of the LCD 16. . Then, in response to a predetermined recording instruction (shooting instruction) operation such as a shutter switch pressing operation, the capture of the digital image data 48 for recording is started.
[0025]
Further, at the time of image reproduction, the digital image data 48 to be reproduced stored in the recording medium 72 is read out by the media control circuit 42, input to the image processing unit 44, and decompressed by a compression / decompression unit (not shown). And transferred to the LCD drive circuit 34. Thereby, an image based on the digital image data 48 acquired by photographing and stored in the recording medium 72 can be reproduced and displayed on the LCD 16.
[0026]
Furthermore, the digital camera 10 according to the present embodiment has an image based on the digital image data 48 as the main image data obtained by photographing, that is, an image based on the sub image data, if necessary, on the subject image. An OSD (On Screen Display) function for superimposing various characters and displaying them on the LCD 16 is provided. For this reason, the image processing unit 44 includes an OSD circuit 100.
[0027]
Also, bitmap data 102 representing each character to be superimposed and displayed by the OSD function is stored in the external ROM 22 in advance, and in this embodiment, when the digital camera 10 is turned on, the bitmap is read from the external ROM 22 by the image processing unit 44. Data 102 is read out and stored in a predetermined area of the SDRAM 20. When operating the OSD function, the necessary bitmap data 102 may be selected from the external ROM 22 and stored in the SDRAM 20.
[0028]
The bitmap data 102 does not directly indicate the color of each pixel by each color component value of RGB, but is configured by address data that specifies an address of a color conversion table 150 described later.
[0029]
The OSD circuit 100 reads out bitmap data 102 indicating a character desired to be superimposed and displayed from the SDRAM 20, converts it into a YC signal, and outputs the YC signal to the video encoder 50 of the LCD drive circuit 34. Is combined with the digital image data 48 obtained by the above, that is, the YC signal representing the subject image at a predetermined mixing ratio (transparency mixing ratio), and a YC signal representing a state in which the character is superimposed on the subject image is generated to generate the NTSC signal. Convert. By supplying the NTSC signal to the LCD 16, the LCD 16 can display an image in which a character is superimposed on the subject image. Note that a predetermined fixed value may be used as the mixing ratio, or the contrast between the character and the background subject image is increased based on shooting conditions, for example, AE (Auto Exposure) information. It may be changeable.
[0030]
FIG. 2 shows a detailed configuration of the OSD circuit 100. As shown in FIG. 2, between the two line memories 104A and 104B for storing the bitmap data 102 transferred from the SDRAM 20 and indicating the entire character to be superimposed, the DMA is transferred between the SDRAM 20 and the line memories 104A and 104B. (Direct Memory Access) The DMAIF 106 for performing transfer and the line memories 104A and 104B are alternately switched, the input control circuit 108 for controlling to write the bitmap data transferred from the SDRAM 20, and the line memories 104A and 104B. Are alternately switched, an output control circuit 114 that reads out the bitmap data 102, a data converter 116 that converts the bitmap data read out by the output control circuit 114 into a YC signal, and a control from the CPU 44A. And a, and CPUIF118 for receiving items.
[0031]
The DMAIF 106 is connected to the input control circuit 108 and the DMA controller 120. The DMA controller 120 is responsible for DMA transfer of the bitmap data 102 from the SDRAM 20 to the line memories 104A and 104B. Specifically, the input control circuit 108 has a read start position from the DMA controller 120 via the DMAIF 106. Read data designation information for designating the address position, the read data amount (that is, the data amount for one line), the data amount to jump to the next read start position, and the like are input. The bitmap data 102 to be read from the SDRAM 20 is specified by the information. The DMA controller 120 is provided outside the OSD circuit 100, for example, on the image processing circuit of the image processing unit 44.
[0032]
The input control circuit 108 is connected to the line memories 104A and 104B. According to the read data designation information from the DMA controller 120, the bitmap data 102 is DMA-transferred from the SDRAM 20 and alternately line by line to the line memories 104A and 104B. It is something to write on. The line memories 104A and 104B are also connected to the output control circuit 114. The output control circuit 114 is connected to the data conversion unit 116, and alternately reads the bitmap data 102 written in the line memories 104A and 104B line by line and outputs the data to the data conversion unit 116.
[0033]
Specifically, the input control circuit 108 and the output control circuit 114 are supplied with timing signals indicating various driving timings such as a horizontal synchronizing signal and a vertical synchronizing signal, and a driving clock from an oscillator (not shown). . In this embodiment, the video encoder 50 is provided with a timing generator (TG) 122 that generates a timing signal, and the OSD circuit 100 and the video encoder 50 use the same timing signal generated by the TG 122. Thus, the drive timings of both are synchronized.
[0034]
The input control circuit 108 includes a counter 130 and a selector 132, and the output control circuit 114 also includes a counter 140 and a selector 142. The input control circuit 108 and the output control circuit 114 recognize the position in the vertical direction by counting the number of input pulses of the horizontal synchronization signal after the vertical synchronization signal is input by the counters 130 and 140, and input each horizontal synchronization signal. The horizontal position can be grasped by counting the number of input pulses of the subsequent drive clock. Accordingly, the character can be enlarged and reduced by controlling the frequency of the driving clock.
[0035]
The input control circuit 108 receives the vertical synchronization signal and starts DMA transfer of the bitmap data 102 from the SDRAM 20 based on the read data designation information. Specifically, after receiving the input of the first horizontal synchronization signal after the input of the vertical synchronization signal, the data of the data amount specified in the horizontal direction is read from the SDRAM 20 from the address position specified by the read data specification information, One of the line memories 104A and 104B is selected by the selector 132, and the read data is stored in the line memory selected by the selector 132. When the next horizontal synchronization signal is input, the reading position is jumped by the designated address, the data of the designated data amount in the horizontal direction is read from the SDRAM 20 from the address position after the jump, and the selector 132 is selected. By switching, the read data is stored in the line memory. Thereafter, by repeating the same processing, the bitmap data 102 can be DMA-transferred from the SDRAM 20 and written alternately to the line memories 104A and 104B line by line.
[0036]
The output control circuit 114 receives the vertical synchronization signal and starts reading the bitmap data 102 from the line memories 104A and 104B. Specifically, after the vertical synchronization signal is input, the first horizontal synchronization signal is input, the selector 142 selects one of the line memories 104A and 104B, and the data is read from the line memory selected by the selector 142. And output to the data converter 116. When the next horizontal synchronization signal is input, the selection of the line memory 104A or 104B by the selector 142 is switched to read the data, and the read data is output to the data converter 116. Thereafter, by repeating the same processing, the character data DMA-transferred from the SDRAM 20 and stored in the line memories 104A and 104B can be alternately read line by line and sent to the data converter 116.
[0037]
The data conversion unit 116 includes a color conversion table 150 for color-converting bitmap data into YC data, and a YC conversion circuit 152 for converting bitmap data into YC data. The color conversion table 150 is a so-called color palette in which luminance data Y value and chroma data Cr and Cb values of 256 colors are stored, and each color is represented by 16-bit data. Specifically, the value of luminance data Y is indicated by 6 bits, and the values of chroma data Cr and Cb are indicated by 5 bits. The values (Y, Cr, Cb) of each color in the color conversion table 150 are set by table data input from the CPU 44A via the CPUIF 118 (color palette can be changed).
[0038]
The YC conversion circuit 152 converts the bitmap data into luminance data Y and chroma data Cr and Cb by reading the value stored at the address position indicated by the bitmap data from the color conversion table 150 (YC data conversion). . The YC conversion circuit 152 outputs the signal representing the luminance data Y to the video encoder 50 together with the CG (character generator) Y signal, the signals indicating the chroma data Cr and Cb, the CGCr signal, and the CGCb signal together with the enable signal CGEN. Hereinafter, the CGY signal, the CGCr signal, and the CGCb signal are collectively referred to as a CGYC signal.
[0039]
The video encoder 50 receives the digital image data 48 acquired by photographing from the SDRAM 20, that is, the YC signal representing the subject image. The video encoder 50 detects the OSD when the enable signal CGEN is H (high level). The CGYC signal and YC signal input from the circuit 100 are combined, and the combined signal is converted into an NTSC signal. When the enable signal CGEN is L (low level), the YC signal is converted into an NTSC signal as it is. It has become.
[0040]
The OSD circuit 100 according to this embodiment includes a memory 112 for storing replacement bitmap data 110 for replacement with a part of the bitmap data 102. That is, the bitmap data 110 corresponds to the replacement image data of the present invention, and the memory 112 corresponds to the replacement image data storage means of the present invention. Note that, similarly to the bitmap data 102, the bitmap data 110 is configured by address data that specifies an address of a color conversion table 150 described later.
[0041]
The memory 112 is connected to the CPUIF 118, and data is mainly written to the memory 112 by the CPU 44A via the CPUIF 118. In the present embodiment, the replacement bitmap data 110 is stored in advance in the external ROM 22, and is read from the external ROM 22 by the CPU 44A and written in the memory 112 at a predetermined timing.
[0042]
The memory 112 is also connected to the output control circuit 114, and the selector 142 of the output control circuit 114 can select the memory 112 in addition to the line memories 104A and 104B. In the output control circuit 114, since the memory 112 can be selected by the selector 142, the selector 142 can be selected by an arbitrary amount of data at an arbitrary timing during transmission of the bitmap data 102 to the data converter 116. By switching from the line memory 104A or 104B to the memory 112, the bitmap data 110 can be read from the memory 112 instead of the bitmap data 102 and sent to the data converter 116. As a result, data obtained by replacing part of the bitmap data 102 with the bitmap data 110 is input to the data converter 116. That is, the selector 142 has a function as a replacement means of the present invention.
[0043]
Each of the input control circuit 108, the output control circuit 114, and the data conversion unit 116 is connected to the CPUIF 118, and the CPU 44A transmits the input control circuit 108, the output control circuit 114, and the data conversion unit 116 via the CPUIF 118. Various control signals are inputted to each of these. That is, the CPU 44 </ b> A controls driving of the input control circuit 108, the output control circuit 114, and the data conversion unit 116.
[0044]
Specifically, the CPU 44A instructs each of the input control circuit 108 and the output control circuit 114 to drive each of the input control circuit 108 and the output control circuit 114 when the characters indicated by the bitmap data 102 are superimposed by the OSD function. Further, when there is a possibility that a part of the character to be superimposed and displayed may be changed and displayed, the CPU 44A reads out the replacement bitmap data 110 used for the change from the external ROM 22 and stores it in the memory 112. Position designation information for designating a replacement position (horizontal and vertical coordinates H and V) in the bitmap data 102 is also stored in the memory 112.
[0045]
The replacement bitmap data 110 is data indicating only a part of the changed character, not the entire character. Also, there may be a plurality of change states. In this case, replacement bitmap data 110 for each change state is stored in the memory 112. That is, the memory 112 can store a plurality of bitmap data 110. In this embodiment, the replacement bitmap data 110 is read from the external ROM 22 and stored in the memory 112 only when there is a possibility of rewriting. However, all replacement data are stored in the memory 112 in advance. The bitmap data 110 may be stored.
[0046]
Further, in the case of performing this rewriting, the CPU 44A transmits a switching signal instructing to switch the selection of the selector 132 to the memory 112 to the output control circuit 114. This switching signal includes an address indicating the read start position of data from the memory 112, information specifying the read data amount, and the like. The replacement bitmap data read from the memory 112 is read based on this information. 110 is designated.
[0047]
The input control circuit 108 and the output control circuit 114 operate as described above while the drive is instructed by the CPU 44A, and alternately transfer the bitmap data 102 DMA-transferred from the SDRAM 20 to the line memories 104A and 104B. Writing and reading line by line and sending the bitmap data 102 to the data converter 116. When a switching signal is input from the CPU 44A, the position designation information is read from the memory 112 and designated by the read information. When the rewrite position is reached, the selection of the selector 142 is switched from the line memory 104A or 104B to the memory 112, and the data corresponding to the read data amount designated from the read start position designated by the switching signal is read from the memory 112 and the data is read. The data is sent to the conversion unit 116. As a result, a part of the bitmap data 102 is replaced (rewritten) with the bitmap data 110 and sent to the data converter 116. Note that the input control circuit 108 may stop the DMA transfer from the SDRAM 20 for the portion of the bitmap data 102 that is to be replaced with the bitmap data 110.
[0048]
Next, as an operation of the present embodiment, an operation when a character is superimposed and displayed on a subject image by the OSD function will be described. FIG. 3 shows a control routine executed by the CPU 44A in this case.
[0049]
In the present embodiment, as shown in FIG. 4, when the digital camera 10 is turned on, the bitmap data 102 is read from the external ROM 22 and stored in a predetermined area of the SDRAM 20. Further, when displaying the subject image, the video encoder 50 is driven regardless of the superimposed display of the character, and after the digital image data 48 indicating the subject image obtained by photographing is temporarily stored in the SDRAM 20, DMA transfer is performed to the video encoder 50, and while the video encoder 50 is being driven, a timing signal common to the video encoder 50 is supplied to the OSD circuit 100 by the TG 122.
[0050]
As shown in FIG. 3, in the case where the CPU 44A superimposes the character on the subject by the OSD function, first, in step 200, the bitmap data 102 indicating the character to be superimposed is designated and notified to the DMA controller 120. To do. The DMA controller 120 sets read data designation information so that the bitmap data 102 designated by this notification is read from the SDRAM 20, and transmits it to the OSD circuit 100.
[0051]
In the next step 202, it is determined whether or not this character is likely to be changed frequently. If there is no possibility that the character is changed, the process proceeds from step 202 to step 204. Instructs the input control circuit 108 and the output control circuit 114 to drive.
[0052]
As a result, driving of the OSD circuit 100 is started, and the bitmap data 102 is DMA-transferred from the SDRAM 20 based on the read data designation information in synchronization with the timing signal from the TG 122, and the line memory 104A, 104B is alternately written line by line, read out line by line by the output control circuit 114, sent to the data converter 116 for YC conversion, and the CGYC signal indicating the result together with the H enable signal CGEN It is output to the video encoder 50. This CGYC signal is synthesized with the digital image data 48 DMA-transferred from the SDRAM 20 by the video encoder 50, that is, the YC signal representing the subject image, and the synthesized signal is converted into an NTSC signal and supplied to the LCD 16, An image in a state where a character based on the bitmap data 102 of the SDRAM 20 is superimposed on the subject image obtained by photographing is displayed on the LCD 16. Then, the process returns from the next step 206 to step 204 until the predetermined timing for ending the superimposed display is reached, and when the superimposed display of the character is continued and the superimposed display is finished, an affirmative determination is made in step 206. Thus, the control routine of FIG. Note that the timing for ending the superimposed display includes a case where the entire character to be superimposed is changed.
[0053]
On the other hand, in the case of a character that may be partially changed, the process proceeds from step 202 to step 210, and the bitmap data 110 for rewriting indicating the changed state is read from the external ROM 22, and the bitmap is read. The replacement position (horizontal and vertical coordinates H, V) on the data 102 is stored in the memory 112 together with position designation information for designating the replacement position.
[0054]
Thereafter, the process proceeds to step 212 to instruct the input control circuit 108 and the output control circuit 114 to drive. As a result, the driving of the OSD circuit 100 is started, and the bitmap data 102 DMA-transferred from the SDRAM 20 is YC converted, and the CGYC signal indicating the result is output to the video encoder 50 together with the H enable signal CGEN. Then, the video encoder 50 displays the image on the LCD 16 in a state in which a character based on the bitmap data 102 of the SDRAM 20 is superimposed on the subject image obtained by photographing in the same manner as described above.
[0055]
At this time, when a part of the character based on the bitmap data 102 is changed to be superimposed and displayed on the subject image, an affirmative determination is made in the next step 214 and the process proceeds to step 216 for replacement for indicating a state to be changed. A switching instruction including information specifying the bitmap data 110 (an address indicating the read start position and a read data amount) is transmitted to the output control circuit 114.
[0056]
In response to this switching instruction, the output control circuit 114 refers to the position designation information (horizontal and vertical coordinates H, V) from the memory 112 and corresponds to the coordinates designated by the position designation information from the line memory 104A or 104B. When it is time to read data, the selection of the selector 142 is switched from the line memory 104A or 104B to the memory 112, and the bitmap data 110 designated by the switching instruction is read from the memory 112. As a result, when the output control circuit 114 reads the bitmap data 102 from the line memory 104A or 104B, a part of the bitmap data 102 can be changed (rewritten) to the bitmap data 110 and read. The read bitmap data 102 or 110 is sent to the data converter 116, processed in the same manner as described above, and the resulting CGYC signal is combined with the YC signal by the video encoder 50, so that it is superimposed on the subject image. A part of the displayed character is changed.
[0057]
Then, the process returns from the next step 218 to step 212 until the predetermined timing for ending the superimposed display of the character is reached, and the superimposed display of the character is continued. As a result, the control routine of FIG. 3 is terminated. Note that the timing for ending the superimposed display includes a case where the entire character to be superimposed is changed.
[0058]
Hereinafter, specifically, as shown in FIG. 4, the bar 300 representing the zoom position, the AF frame frame 302, and “Tele” and “Wide” indicating the tele end and wide end directions of the bar 300 are operated in the auto shooting mode. A character composed of various character strings 304 such as “Auto” indicating that it is in the middle and “8:31” indicating the shooting time is superimposed on the subject image, and the bar 300 portion of the character is displayed. Will be described in connection with a change in the zoom position. The zoom position is changed in response to an input of an instruction to change the zoom position (shooting magnification) by the operation of the operation unit 18 by the photographer.
[0059]
In this case, the bitmap data 110 for replacement indicating the bar 300 representing the zoom position is stored in the memory 112 in accordance with each of the plurality of zoom positions.
[0060]
Bit map data 102A indicating a character including a bar 300, an AF frame frame 302, and various character strings 304 is selected from the various bitmap data 102 stored in the SDRAM 20 and DMA-transferred to the OSD circuit 100. Is done. When the selector 142 sends the bitmap data 102A transferred from the SDRAM 20 to the data converter 116, the portion of the bar 300 on the bitmap data 102A is switched instead of the bitmap data 102A. The bitmap data 110 specified by the signal is read from the memory 112 and sent to the data converter 116, converted to a CGYC signal by the data converter 116, and output to the video encoder 50.
[0061]
That is, the portion of the bar 300, which is a part of the bitmap data 102A, is rewritten to the bitmap data 110 and YC converted, so that the video encoder 50 DMA-transfers this CGYC signal from the SDRAM 20 and inputs the digital image. When combined with the data 48, that is, the YC signal indicating the subject image, and displayed on the LCD 16, the portion of the bar 300 of the characters superimposed on the subject image is indicated by the bitmap data 110 on the LCD 16. Be changed.
[0062]
Therefore, if the CPU 44A inputs a switching signal designating the bitmap data 110 corresponding to the zoom position after the change according to the change of the zoom position, the character bar 300 according to the zoom position at the time of shooting the subject. The character can be superimposed and displayed on the subject image.
[0063]
As described above, the OSD circuit 100 is provided with the memory 112 for storing the replacement bitmap data 110 for replacement with a part of the bitmap data 102 transferred from the SDRAM 20. The bit map data 102 transferred from the SDRAM 20 and the bit map data 110 stored in the memory 112 can be switched and output at any coordinate position (H, V), thereby changing a part of the character. In this case, it is not necessary to rewrite the bitmap data 102 on the SDRAM 20. As a result, the data transfer amount from the external ROM 22 to the SDRAM 20 can be reduced, the data transfer from the main storage device to the OSD circuit or the video encoder is not in time, and the display is disturbed or the processing speed of other functions is reduced. Can be prevented.
[0064]
【The invention's effect】
As described above, the present invention has an excellent effect that the amount of data transfer can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an electric system of a digital still camera according to an embodiment.
FIG. 2 is a block diagram showing a detailed configuration of an OSD circuit according to the present embodiment.
FIG. 3 is a flowchart showing a control routine executed by a CPU when operating an OSD function.
FIG. 4 is a conceptual diagram showing an operation example of the OSD circuit according to the present embodiment.
[Explanation of symbols]
10 Digital still camera
20 SDRAM
22 External ROM
24 Main control unit
36 Memory control circuit
44 Image processing unit
44A CPU
48 Digital image data
50 video encoder
100 OSD circuit
102 Bitmap data
104A, 104B line memory
108 Input control circuit
110 Bitmap data for replacement
112 memory
114 Output control circuit
116 Data converter
122 TG
130 counter
132 Selector
140 counters
142 Selector

Claims (2)

An on-screen display device that superimposes and displays an image based on sub-image data read from a predetermined storage unit on an image based on main image data,
Replacement image data storage means for storing replacement image data for replacement with a part of the sub image data;
Replacement means for replacing a part of the sub image data read from the predetermined storage means with the replacement image data stored in the replacement image data storage means;
An on-screen display device comprising: The replacement unit determines a replacement position on the sub image data based on setting information input from the outside.
The on-screen display device according to claim 1.

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