JPH0358570A - Picture data coding system - Google Patents

Abstract

PURPOSE:To save data quantity of a binarized data by generating a coded data in which a kind of quantization step is added to a binary code. CONSTITUTION:A quantization step selection circuit 4 measures an amplitude level of a picture signal subjected to sample-and-hold processing and outputs a selection signal 5a and a step class signal. Then a selection circuit 7 outputs a sampled and held picture signal to a prescribed quantization circuit, e.g. 6a according to a selection signal 5a and a quantization circuit 6a quantizes the sampled and held picture signal. Since the quantized picture signal is inputted to a coding circuit 8 via a selection circuit 9, the coding circuit 8 converts the quantized picture signal into a binary code and adds the quantized step class representing by the step class signal to output the result from an output terminal 10. Thus, the quantization level number is reduced and the data quantity of binarized data is saved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image data encoding method for handling black-and-white multivalued image data, and particularly to an image data encoding method including a plurality of quantization steps of image data.

[Conventional technology]

Conventionally, in this type of image data encoding method, there is no standard encoding method for black and white multivalued image data (hereinafter simply referred to as image data), and when handling such data, compression processing etc. Data storage or data transmission is performed after converting the data into a binary code using a constant quantization step that does not depend on the amplitude level of the original data.

[Problem that the invention attempts to solve]

In the conventional image data encoding method described above, when storing monochrome multilevel image data in the database of a computer system or transmitting the data through a communication line, the image data is not compressed, but is encoded using a fixed quantization step. 2
This is done after converting to decimal code. For this reason, the amount of image data after conversion becomes enormous, requiring a large-scale and large-volume data storage device such as a magnetic disk in a computer system, and it also takes a large amount of time to transmit image data through a communication line. There is a drawback.

[Means to solve the problem]

The image data encoding method according to the present invention divides the maximum amplitude level of image data into n parts, provides a nil visualization step corresponding to the divided amplitude levels, and measures the amplitude level of the image data to be quantized. , one of the 1111 quantization steps corresponding to the amplitude level is selected to quantize the image data, and the result is converted into a binary code. At the same time, the selected quantization step is The ME of the encoding step is added to the binary code to create encoded data.

[Effect]

Since the present invention can eliminate the number of quantization levels, it is possible to reduce the amount of binary encoded data.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of an image data encoding method according to the present invention. In the figure, 1 is an input terminal into which an analog image signal (hereinafter referred to as analog image signal) is input, 2 is a sampling circuit that samples this analog image signal at a constant period, and 3 is a sampling circuit that samples this sampled image signal at a constant rate. Sample and hold circuit for holding time, 4
is a selection signal 5&re which measures the amplitude level of a number-held image signal and selects a quantization circuit that performs quantization at a quantization step corresponding to the amplitude level, and a step type signal 5b which indicates the selected quantization step type. 6&~6n are quantization circuits that quantize the sampled and held image signals; 7 inputs the sampled and held image signals to predetermined quantization circuits 6a to 6n according to the selection signal 5a; 8 is an encoding circuit that converts the quantized image signal into a binary code, adds the quantization step type indicated by the step type signal 5b, and outputs it; 9 is a selected quantization circuit ( For example, 6m)! ) A selection circuit outputs both quantized signals to an encoding circuit 8, and 10 is an output terminal from which a binary code to which a quantization step type is added is output.

In addition, in Fig. 2, the horizontal axis represents the image signal level L O "" L
4, and by taking the quantization step So=Sg on the vertical axis, this relationship between the image signal level and the quantization step is shown, and the image signal level L●~LIILI~L1tL1~LS
, t,s to L4, the quantization step so
-xss is allocated. Figure 3 shows how a time-series continuous image signal is quantized by various quantization steps depending on its amplitude level. Next, the operation of the image data encoding method with the above configuration will be explained. First, the analog image signal input to input terminal 1 is sent to sampling circuit 2.
The signal is sampled at regular intervals and input to the sampling and hold circuit 3. This sample and hold circuit 3 holds this numbered image signal for a certain period of time. Then, the quantization step selection 1<circuit 4 measures the amplitude level of the temple-held image signal and outputs a selection signal 5a and a step type signal. Then, the selection circuit I selects the sampled and held artist name and outputs it to a predetermined quantization circuit, for example, 6a, in accordance with a selection signal 5m. This quantization circuit 6a quantizes the sampled and held image signal. This quantized image signal is input to the encoding circuit 8 via the selection circuit 9, so this encoding circuit 8 converts the quantized image signal into a binary code and also converts the quantized image signal into a binary code indicated by the step signal. It is possible to add the conversion step type and output it from the output terminal 10.

In the above explanation, the case where the black-and-white multilevel image data is divided into four at the maximum amplitude level iL● to L4 1 was shown, but the invention is not limited to this, and it goes without saying that the same can be done even if the image data is divided into n. [Effect of the Dawn] According to the image data encoding method according to the present invention, the maximum amplitude level of monochrome multivalued image data is divided into n, and n types of quantization steps corresponding to the n divided amplitude levels are provided, The amplitude rep J of the image data to be quantized is measured, one of the n types of quantization steps corresponding to the amplitude level is selected to quantize the image data, and the result is converted into a binary code. By creating encoded data by adding the type of quantization step selected during image data quantization to the binary code at the same time as converting the image data to Since the number of quantization levels can be reduced, there is an effect that the amount of binary encoded data can be reduced.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of the image data encoding method according to this invention, Fig. 2 is a diagram showing the relationship between the image quality δ level and the quantization step in Fig. 1, and Fig. 3 1 is a diagram showing an example in which the image data of FIG. 1 is converted into f-sons by various quantization steps. 1・●・●input terminal, 2・●●・sampling circuit, 3
...●Sample hold circuit, 4●●・●Quantization step selection circuit, 5m ・●・●selection signal, 5b・●・
・Step type signal, 6a to 6n...quantization circuit,
T...● selection circuit, 8●●●・encoding circuit, 9●●・
・Selection circuit, 10●・●● output terminal.

Claims (1)

[Claims] In an image data encoding method that handles black-and-white multivalued image data, the maximum amplitude level of the image data is divided into n parts, and n types of quantization steps are provided corresponding to the divided amplitude levels, and the image data to be quantized is divided into n parts. The amplitude level is measured, one of the n types of quantization steps corresponding to the amplitude level is selected to quantize the image data, the result is converted to a binary code, and the image data is quantized at the same time. An image data encoding method characterized in that encoded data is created by adding a type of quantization step selected in conjunction with a binary code to a binary code.