JP2920987B2 - Title picture insertion device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a title picture insertion device that allows only a colored part of a title picture to be inserted as a color title into a background video.

[Related Art] Recently, home video cameras equipped with various editing functions are increasing, and a title insertion which is useful for inserting a title character at the beginning of a recorded video of a family trip, an athletic meet, or the like. Popular with features. However, the conventional title image insertion device has many restrictions such as appropriately selecting and using a title suitable for the purpose among several types of titles stored in the ROM in the video camera in advance, and is arbitrarily created. A user who wants to freely superimpose title characters needs to purchase a video camera equipped with the title picture insertion device 1 shown in FIG.

The conventional title image insertion device 1 shown in FIG. 1 uses a color pen or the like to write a title character on a white value drawing paper or the like, shoots it as a title image, and temporarily stores it in the image memory 2. It is. However, image memory 2
Instead of storing the title image as it is, the title image is subjected to threshold determination in the preceding binarization circuit 3 and stored as a black and white binary image. And
The title character stored in the image memory 2 as a black character is read from the image memory 2 as a specific single color character,
The changeover switch 5 driven by the changeover control circuit 4 overlaps the background image.

[Problem to be Solved by the Invention] In the conventional title picture insertion apparatus 1 described above, the binarization circuit 3 for extracting only the color characters from the title picture created using the drawing paper is simply a luminance level change. Is divided into colored portions and non-colored portions, and binary data of white or black is written in the image memory 2. Title characters written as black characters are designated in advance among colors such as blue, red or green. Because one color is used for superimposing, the colors that can be displayed as title characters are limited to only one color, and it was not possible to insert a color title with a favorite color.

Also, if the white value drawing paper used for the title image is old and slightly yellowed, or if the floating color is lightly colored due to the use of the back of a newspaper insert advertisement, write on the title image. It may be difficult to distinguish between the color title and the part of the background that should be achromatic in nature, and parts other than color characters may be extracted, or color characters may not be extracted at all. Had a challenge.

Japanese Patent Laid-Open Publication No. Sho 63-172577 discloses a video camera in which title characters are inserted into a video image. However, in this case, the color of the title character that can be used is basically limited to black and white, and if the title character is to be colored to a color other than black and white, the video signal of the character insertion portion is set to a predetermined color signal For this reason, for example, it is not possible to insert a title picture drawn using multiple colors on blank paper into a video image, which poses a problem that the application range is extremely limited. Met.

Further, Japanese Patent Application Laid-Open No. 63-104593 discloses a device capable of synthesizing another image with an arbitrary color portion of the image. However, for example, when replacing the background of a person image (parent image) on a white background with a child image such as a mountain range, the address of a white portion having a certain area or more is specified, and the address is determined. Is only replaced and synthesized with the portrait image of the part corresponding to the image, and the color of the replacement part of the parent image to be subjected to the synthesis replacement is limited to a specific single color such as white to the last. There is a problem that a technique of inserting a color part into a parent image cannot be used.

Japanese Unexamined Patent Publication No. 1-29791, "Superimpose apparatus" discloses a camera-integrated video tape recorder capable of performing spur imposition both during recording and during reproduction. However, this configuration focuses on the luminance signal of the image for superimposition transmitted from the camera processing unit, and creates a luminance signal for the position gate by digitally converting this luminance signal.
The clipping of the image for superimposition is based solely on the luminance signal, and a colored part that cannot be discriminated by the luminance signal alone cannot be selected as a position gate, that is, a target to be superimposed. However, there is a problem in that it is not possible to provide a flexible use method such as extracting only information and inserting it into a recorded image or a reproduced image.

Japanese Patent Laid-Open No. 1-318385, entitled "Camera Integrated Magnetic Recording / Reproducing Apparatus," includes a video camera having a chroma key function of generating a key signal from a chroma signal and inserting a child image into a parent image according to the key signal. It has been disclosed. However, this is a configuration in which a specific color signal (analog red color difference signal) in a child image is compared with a reference level and is used as a chroma key signal. In the signal, a position gate in consideration of a luminance signal or a chroma key signal for position gates of a plurality of colors cannot be generated, and there is a problem that an application range is limited. In addition, the parent image is compressed and decompressed by controlling reading and writing to and from the memory.
Since the child image is not compressed and decompressed, it has a problem that it is not suitable for use such as storing a large number of chroma key signals as title images.

JP-A-52-44120, "Color information detection circuit"
Discloses a circuit which extracts an image portion of a component having a predetermined range of hue, saturation, and lightness in a color image signal and enables a chroma key which is not affected by a luminance signal level. However, the key signal generation principle is that a key signal is generated by comparing a value obtained by dividing (normalizing) a red color difference signal and a blue color difference signal by a luminance signal with upper and lower threshold values, and a plurality of divisions are performed. Instead of executing the above, a threshold discriminant obtained by multiplying the upper and lower thresholds by the luminance signal and denormalizing them is used. The circuit configuration is very complicated, such as requiring four comparators or a circuit for correcting a luminance signal with a luminance peak value. For example, only a colored portion of a title picture taken by a home video camera is extracted. Assuming the intended use, it is a fact that methods such as coefficient multiplication and luminance peak value correction impose manufacturing costs and hinder practicality. For example, a red color difference signal and a blue color difference signal From the color difference sequential signals appear alternately every it was clear that is different from the circuit of simple configuration that focus on the point of performing a key signal extracted in consideration of the luminance signal which is not affected by the white balance adjustment.

Japanese Patent Application Laid-Open No. Sho 62-11392, "Keying Signal Generation Circuit", discloses a circuit which does not need to switch the threshold level according to the background color based on the conditions for generating the chroma key signal. However, this circuit compares the sample value of the peak value detection output signal of the color difference signal relating to the background color with the input color difference signal, and distinguishes the background and the subject from the comparison error. In order to create a key signal by focusing on two types of color difference signals,
It is good to create a key signal only for a background such as an outdoor mountain range, but if you try to generate a key signal at the character part of the title image drawn on a blank sheet indoors, the correct key signal In some cases, extraction becomes difficult, and there is a problem in that the method cannot be used for title image insertion unless a key signal generation method that takes into account a luminance signal that is not affected by white balance adjustment is used. Further, in this device, a special hue portion of a parent image is used as a key signal, but a specific hue portion of a child image is not used as a key signal. It was the cause of the fundamental difference in the idea of the consequence, and it was clear that it was not suitable for inserting a title picture.

Further, Japanese Patent Application Laid-Open No. Sho 60-10893, "Key Signal Detection Circuit in Chroma Key System" discloses a circuit for inserting a child image into a predetermined hue portion of a parent image. However, this circuit focuses on two color difference signals of a parent image, that is, a red color difference signal and a blue color difference signal, and logically inverts the polarity upper and lower threshold output of the former and the upper threshold output of the latter. A chroma key signal is formed by multiplying the signals. For example, as in a video camera using a solid-state image sensor (CCD), white balance adjustment is performed on one line output in the process of generating color difference sequential signals by mixing two lines. In a system that employs a method of multiplying by a coefficient and adding to one line output, the color difference signal situation is a so-called pseudo color difference signal corrected by the color temperature of the subject, and the luminance is not affected by white balance adjustment. Unless threshold discrimination focusing on the signal is used together, the detection of the key signal is greatly affected by the white balance adjustment. In the captured parent image were those facing the problems such as prone to differences in chroma key content.

Means for Solving the Problems The present invention has solved the above-mentioned problems, and has an image memory for taking in a digital video color video signal for a title image, and a title image read from the image memory. , A luminance signal and a color difference signal are sequentially extracted from the color video signal, a threshold value is determined based on a certain threshold value to determine a colored portion, and a color key signal indicating the presence of the colored portion is generated. A color key generating circuit; and a color title inserting means for switching upon receiving a color key signal generated by the color key generating circuit and replacing a part of a background video signal with the output of the image memory. It is assumed that.

[Operation] The present invention extracts an image memory for taking in a digital video color video signal for a title image, and extracts a luminance signal and a color signal from the color video signal for the title image read from the image memory. A color key signal is generated by comparing each of the color key portions with a predetermined threshold value, the color title signal is switched by the generated color key signal, and a part of the background video signal is stored in an image memory. , So that any color title can be inserted into any background video.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram showing one embodiment of a title picture insertion device of the present invention.

In FIG. 1, a title image insertion device 11 is applied to a home video camera, and a video signal is a luminance signal Y.
And color signals C, and each is processed as digital data. For this reason, the video signal captured via the optical system and the video processing system undergoes luminance / color separation processing, and then the luminance signal Y and the chrominance signal C are converted to the AD converters 12 and 1, respectively.
Converted to digital data in 3. The luminance signal Y is
The color signal C is sent to a DA converter 15 via a changeover switch 14 having a data selector as a color title insertion means, and one color signal C is alternately converted by a decoder 16 into a red color difference signal RY and a blue color difference signal BY. After being converted to a color difference sequential signal connected to the
Is sent to the DA converter 19 via the encoder 18 which performs the reverse process.

The image memory 20 is controlled for writing and reading by the memory control circuit 21, takes in luminance data and color data from the subsequent stage of the switches 14 and 17, and switches the read luminance data and color data to one input of the switch 1. And Reference numeral 22 denotes a color key generation circuit which generates a color key signal for switching the changeover switches 14 and 17, and a threshold value discrimination circuit 23 corresponding to the luminance data and the color data relating to the title image read from the image memory 20, respectively. , 24, a threshold value is discriminated, and a color key signal indicating a color portion exceeding the threshold value obtained as a result of the discrimination is mixed by a mixing circuit 25 before being used as a switching signal for the changeover switches 14, 17. , Is collectively controlled by the operation color extraction circuit 26.

First, when importing a title image, the title characters are written on a white drawing sheet using a color pen. Then, the image paper on which the title character is written is photographed, and the photographing data at that time is taken into the image memory 20.

Next, the image memory 20 is set to the read mode when a video in which color title characters are to be superimposed is photographed.
At this time, the luminance data and color data relating to the title image read from the image memory 20 are stored in the color key generation circuit 22.
Are subjected to threshold value determination in the threshold value determination circuits 23 and 24, and a color key signal corresponding to a color character portion is generated. Therefore, the changeover switches 14 and 17 are switched to the image memory 20 only when the color title portion of the title image is being read, and the luminance data and the color data constituting the color title read from the image memory 20 are changed. Is output instead of the video data currently being captured.

In this case, the threshold value is determined based on the luminance signal Y and the color signal C, and the color signal C is individually determined for each of the red color difference signal RY and the blue color difference signal BY. When viewed only from the luminance level, color characters using yellow or cyan, which are very close to white, can be identified well. That is, the luminance level has a small level difference of 0.89 with respect to white 1.0, and the yellow color title, which has been considered to be difficult to extract by threshold value discrimination based only on the luminance level, also changes the color signal level between red and blue here. In order to determine the threshold value for each of the color difference signals RY and BY, 0.11 is set for each of the white color whose absolute value is 0.
And yellow having a color difference signal level of 0.89 can be determined as a threshold value with a sufficient margin for determination.

As described above, since the title image insertion device 11 determines the threshold value of the title image stored in the image memory 20 as digital data, the generation accuracy of the color key signal by the threshold value determination is extremely high. Color titles written on a drawing paper with a color pen can be accurately extracted regardless of the color of the color pen used, and a color title of any color can be inserted into any background video .

In the above embodiment, the title image itself is stored in the image memory 20 as data. However, for example, as in the title image insertion device 31 shown in FIG. Data decompression circuit 33
And the number of bits of the write data in the image memory 20 can be reduced by using a run-length code or the like, so that the storage capacity of the image memory 20 can be reduced. That is, if the capacity of the used image memory 20 itself is saved, or if the image memory 20 having the same storage capacity is used, the number of title images that can be stored can be doubled in inverse proportion to the data compression ratio.

Furthermore, instead of storing the title image itself in the image memory 20, the result of the threshold value determination may be stored in the image memory 20 as color title data. The title image stored in the image memory 20 is not limited to a natural image, but may be an artificially colored graphic image or the like.

The color key signal generated by the color key generation circuit 22 may be generated only in a color title portion having a specific color sandwiched between upper and lower thresholds. Only specific colors can be extracted and used as color titles.

Furthermore, the title image insertion devices 11 and 31 can be widely applied not only to video cameras but also to video equipment such as video tape recorders.

[Effects of the Invention] As described above, the present invention relates to an image memory that takes in a digital video color video signal for a title image, and a title image read from the image memory. A luminance signal and a color difference signal are sequentially extracted, a color key signal is generated by judging a colored portion by judging a threshold value based on a certain threshold value, and a color title inserting means is generated by the generated color key signal. In this configuration, a part of the background video signal is replaced with the output of the image memory. Therefore, the threshold value of the title image stored as digital data in the image memory can be determined. Can be captured on the same path, especially in a chroma processing circuit like a home video camera. It is suitable for a device that handles color difference signals, and the color difference signals can be sequentially thresholded by lowering the threshold value determination result of the luminance signal that is not affected by white balance adjustment. The generation accuracy is extremely high, and it is possible to freely capture and capture the title image regardless of whether it is indoors or outdoors, and this makes it possible to determine the key signal by focusing only on the color signal level or only the luminance signal level. It is difficult to extract yellow and cyan, which have a brightness close to white, which can be clearly distinguished from white, and can be accurately extracted regardless of the color of the color pen used. For example, a title can be written using a color pen of any color, so that any color title can be inserted into any background image. It exhibits an excellent effect such as can.

In addition, the present invention provides a data compression circuit and a data decompression circuit before and after the image memory, thereby reducing the number of bits of title image data stored in the image memory, saving the capacity of the image memory, or saving the same memory. With a large capacity image memory, the number of title images that can be stored can be doubled in inverse proportion to the data compression ratio.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the title picture insertion device of the present invention, FIG. 2 is a circuit diagram showing another embodiment of the title picture insertion device of the present invention, and FIG. FIG. 10 is a circuit configuration diagram illustrating an example of a conventional title image insertion device. 11,31… Title insertion device 12,13… AD converter 14,17… Changeover switch 15,19… DA converter 20 …… Image memory 22 …… Color key generation circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-172577 (JP, A) JP-A-63-104593 (JP, A) JP-A-1-293793 (JP, A) JP-A-60-1985 10893 (JP, A) JP-A-1-318385 (JP, A) JP-A-52-44120 (JP, A) JP-A-62-11392 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) H04N 9/74 H04N 9/75

Claims (2)

(57) [Claims] An image memory for taking in a digital video color video signal for a title image, and a luminance signal and a color difference signal are sequentially extracted from the color video signal for the title image read from the image memory, A color key generation circuit that determines a colored portion in which a threshold is determined based on a fixed threshold value and generates a color key signal indicating the presence of the colored portion, and a color key signal generated by the color key generation circuit. Switching after receiving
A title picture inserting apparatus comprising a color title inserting means for replacing a part of a background video signal with the output of the image memory. 2. The image memory according to claim 1, further comprising a data compression circuit at a preceding stage for compressing the color video signal, and a data decompression circuit at a subsequent stage for expanding and restoring the color-compressed color video signal. 2. The title image insertion device according to claim 1, wherein: