JPS6128262B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to encoding of image signals.

In order to transmit and store images, it is necessary to encode image signals efficiently, and there are various techniques such as band compression in facsimile transmission and efficient use of storage devices through image data compression in image databases.
Techniques for efficiently encoding and transmitting or storing image signals have been actively researched, and in general, it can be said that efficiently encoding image signals is an equally widespread concept.

By the way, if we consider the purpose of using images in general, it is often the case that the images that are reproduced after being transmitted or stored do not necessarily need to be faithful to the original images in terms of image quality or shape.

For example, suppose that in facsimile transmission, a portion consisting of characters, symbols, figures, etc. and a portion showing a photograph are simultaneously transmitted. In this case, even if the pixel shading of the photograph part must be displayed in many gradations, the number of gradations of the pixel shading of the text and symbol parts is limited to two (in other words, it is limited to white or black). In many cases, it is sufficient to display the figure in two gradations. It goes without saying that an image with a smaller number of gradations can be encoded and transmitted or stored with higher efficiency.

FIG. 1 is a waveform diagram showing an example of quantization of an image signal, in which the horizontal axis represents time, and points added at equal intervals on the horizontal axis represent sample points. Also, the vertical axis is the amplitude. FIG. 1a shows a video image signal obtained by scanning an image with an image scanner, and FIG. 1b shows a quantized image signal obtained by quantizing the video image signal into five gradations for each sample point. FIG. 1c shows a quantized image signal obtained by quantizing the video image signal into two gradations for each sample point. The portion of the photograph mentioned above is quantized and transmitted, for example, as shown in FIG. 1b. On the other hand, since characters and other parts should originally be expressed in two gradations, the shading of the pixels is white or black, this may be caused by uneven illuminance on the screen during image scanning or the characteristics of the scanning device. Therefore, even if the video image signal becomes as shown in Figure 1a, it should not be quantized as shown in Figure 1b, but should be quantized to two gradations as shown in Figure 1c. be.

The signal shown in FIG. 1c is an extremely simple signal compared to the signal shown in FIG. 1b, and the amount of code when encoded is about a fraction of that of the signal shown in FIG. 1b.

Furthermore, when transmitting or storing an image, there are cases where it is not necessary to transmit or store the entire image obtained by scanning the original image, but only a part of it. FIG. 2 is an explanatory diagram showing the relationship between the original image and the transmitted image. FIG. 2a represents the original image and is composed of parts A, B, C, and D. FIG. 2b represents the image to be transmitted and is composed of portions B and D of the original image. Original image middle B
If the necessary information exists only in the sections D and D, only that section needs to be transmitted as shown in FIG. 2b. By transmitting only the portion shown in FIG. 2b, rather than transmitting the entire image shown in FIG. 2a, the code to be transmitted and the time required to transmit the code can be reduced.

Even in conventional image transmission devices and image storage devices, it is possible to partially change the number of gradations or select only the necessary portions for encoding.

However, in order to do this, it is necessary to, for example, put a mark on the edge of the original image or attach a sliding marker on the carrier sheet and detect it during scanning, or input a numerical value representing the corresponding part from a keyboard etc. It is possible to instruct which part to perform which kind of encoding process by monitoring where the scanner is scanning and by using a switch or the like to indicate the relevant part. is necessary.

In other words, in order to carry out the method described above, it is necessary to mark each image, insert it into a carrier sheet, key in, or monitor the scanning position, which is a disadvantage in that it requires a lot of manpower. There is.

By the way, when transmitting and storing images, the format of the image is limited to some extent, so the second
As illustrated in the figure, which part of the image shape is transmitted is limited to some extent, and the image quality of which part of the image is transmitted with the gradation as shown in Figure 1 b, and the image quality of that part is changed to the image quality of that part as shown in Figure 1 c. There are also many applications in which there are certain limitations as to whether or not the gradation can be transmitted. Examples include forms such as family registers and seal certificates at government offices, and designated forms at companies. Moreover, in such cases, it is often the case that a large number of certain formats are transmitted or stored in succession.

This invention was made in view of the above circumstances, and provides an image encoding device that is efficient and can save manpower when images in a certain format are continuously transmitted or stored. This is what we provide. Embodiments of the invention will be described below with reference to the drawings.

FIG. 3 is a block diagram showing an embodiment of the present invention, in which 31 is a format indication detector;
2 is a format storage unit, 33 is an image scanner, 34 is a two-tone signal encoder, 35 is a multi-tone signal encoder, and 36 is a switch.

Here, instructions for image parts that require transmission or storage and instructions for image parts that require encoding of multi-tone signals are performed using sliding markers on the carrier sheet. Detector 3
1 is nothing but the detector of this marker. This marker detector can be added to the image scanner 33 to detect the position of the marker in parallel with scanning the image. In this case, the format instruction detector 31 may be configured to receive a scanning signal from the image scanner 33 and scan the marker in synchronization with the scanning signal, or may also include an image of the marker from the image scanner 33. It can also be configured to receive an image signal and detect a marker from this image signal.

Now, when a large number of images in the same format are to be encoded in succession, the first image is placed on a carrier sheet and a sliding marker is set according to the purpose. Further, a storage instruction signal A is applied to the form storage unit 32 via the conductor 37 by means such as a switch, and the form storage unit 32 becomes ready for storage. The image scanner 33 starts image scanning, and the video image signal D is sent to the two-tone signal encoder 34 and the multi-tone signal encoder 35.
is input. However, both encoders are controlled to stop operating until the format indicator detector 31 detects a marker indicating the beginning of a portion that requires encoding. When a marker indicating the beginning of the portion of the image that requires encoding is detected, the format instruction detector 31 generates a format instruction signal C and outputs the format instruction signal C to the format storage section 3.
Send to 2. The format storage unit 32 stores the scanning location, that is, the position of the marker at the time when the signal C is generated, and at the same time stores the scanning location, that is, the position of the marker at the time when the signal C is generated. A control signal is generated to start the operation of the two-tone signal encoder 34. The two-tone signal encoder 34 is shown in FIG.
The image signal D is encoded as a binary signal as shown in FIG. 1c, and a code E is output. The switch 36 is also controlled by the format storage section 32, and selects and outputs the output E of the two-tone signal encoder 34.

Next, when the format instruction detector 31 detects a marker indicating the beginning of the image portion that requires multi-tone encoding, the format storage section 32 receives the format instruction signal C, and
At the same time as storing the position of the marker, the operation of the two-tone signal encoder 34 is stopped, and the multi-tone signal encoder 35 is stopped.
A control signal is generated to start the operation of the switch 36 and to switch the switch 36. The multi-gradation signal encoder 35 encodes the signal D as shown in FIG. 1a into a multi-gradation signal as shown in FIG. 1b, and outputs the code F. The switch 36 selects and outputs code F instead of code F. Note that upon this switching, encoding is performed so that the occurrence of switching can be identified.

Thereafter, when a marker indicating the end of the portion requiring multi-gradation encoding is detected, the format storage unit 32
stores the marker position, and outputs a control signal for stopping the operation of the multi-gradation signal encoder 35, restarting the operation of the two-gradation signal encoder 34, and switching the switch.

Furthermore, when a marker indicating the end of an image portion that requires encoding is detected, the format storage unit 32 similarly stores the marker position and stops the two-tone signal encoder 34 and the multi-tone signal encoder 35. A control signal is generated to cause the Thereafter, the image scanning is continued by the scanner 33, and the encoding is stopped until a marker indicating the start of a portion requiring encoding is detected again or until the scanning of the image is completed. During the period when encoding is stopped, the format storage section 32 can also generate a control signal to cause scanning to be performed at a higher speed than usual.

Now, after the encoding of the first image is completed as described above, the position of each marker detected when scanning the first image is stored in the format storage section 32.

When encoding the second and subsequent images of the same format, no special operations such as using a carrier sheet are required. That is, when the scanning of the second and subsequent images is started, the format storage unit 32 compares the scanning position every moment with the marker position stored during the scanning of the first image, and determines the point at which they match. As if the format instruction signal C was received from the format instruction detector 31, signals for controlling the operations of the scanner 33, the two-tone signal encoder 34, the multi-gradation signal encoder 35, and the switch 36 are generated. . As a result, the second and subsequent images will be encoded in exactly the same way as the first image. Here, the format storage section 32 receives a memory release signal B from a push button switch or the like (not shown) or receives a memory instruction signal A until it scans and encodes an image in a different format. , shall maintain format memory.

In the above embodiment, the format was specified using markers on the carrier sheet, but other methods such as marking, keying in numerical values, monitoring the scanning position and using a switch to specify the format may also be used. Similar formatting instructions are also possible. Regarding the encoding format instruction, in the above embodiment, the part that requires encoding is specified, and the part that requires multi-gradation signal encoding instead of two-gradation signal encoding is specified, but the image Instructions regarding the shape of the image, such as expansion, contraction, partial movement, and rotation, as well as instructions regarding image quality, such as image resolution (scanning line density and sampling point density) and edge enhancement processing, can be handled as format instructions in the above embodiment. It is possible.

As described above, the image encoding device according to the present invention has means for detecting a format instruction regarding the shape and image quality of an image for transmission or storage, and means for storing the format, Since it is configured to encode images according to This eliminates the need for the operator to give instructions for each image, thus saving manpower.

[Brief explanation of the drawing]

Fig. 1 is a waveform diagram showing an example of quantization of an image signal, Fig. 2 is an explanatory diagram showing the relationship between an original image and a transmitted image, and Fig. 3 is a block diagram showing an embodiment of the present invention. be. In the figure, 31 is a format instruction detector, 32 is a format storage section, 33 is an image scanner, 34 is a two-gradation signal encoder, 35 is a multi-gradation signal encoder, and 36 is a switch.

Claims (1)

[Claims] 1. An image encoding device that encodes an image for transmission or storage, including an image scanner that scans the image and generates an image signal, and a portion of the image to be encoded and/or expressed by encoding. a format instruction detector that outputs a format instruction signal that instructs the quality of the image to be achieved or the processing that should be performed when expressing the image; and a format instruction signal that is the output of the format instruction detector at the scan timing of the image scanner. When encoding the first image in the same format, the format storage unit stores the associated format, and outputs the format instruction signal, which is the output of the format instruction detector, as it is, and encodes the second and subsequent images in the same format. For encoding, means for outputting a format instruction signal read from the format storage section in response to the scanning timing of the image scanner, and means for inputting the image signal output from the image scanner and encoding each using a different method. a plurality of types of encoders to encode and output the image signal from the image scanner according to the output format instruction signal; An image encoding device comprising: means for controlling a switching operation to determine whether to stop encoding and outputting a signal.