JPH04292077A - Picture data output control method - Google Patents

Abstract

PURPOSE:To shorten time required for output by outputting irreducible minimum amounts of encoding data to restore picture with designated picture quality. CONSTITUTION:The picture data output control method outputting the encoding data being encoded by dividing the original picture into plural steps is provided with a picture quality storage part 12 storing the picture quality estimates of the restore picture to be restored from the encoding data up to each step. By referring to the picture quality storage part 12, the encoding data up to the steps of the picture quality more than the designated picture quality is selected and outputted.

Description

[Detailed description of the invention]

(Table of Contents) Industrial Application Fields Prior Art (FIG. 7) Problems to be Solved by the Invention Means for Solving the Problems (FIG. 1) Working Examples (a) Description of the First Embodiment ( Figures 2 to 4) (b)
Explanation of the second embodiment (FIGS. 5 and 6) (c) Explanation of other embodiments Effects of the invention

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data output control method for controlling the output of encoded data obtained by hierarchically encoding a multivalued image.

[0003] In order to store image data, especially data for halftone images and color images, or to transmit it at high speed and with high quality, it is necessary to calculate the gradation value of each pixel. It is necessary to encode with high efficiency.

[0004] For this reason, as a method for encoding image data in image database searches, etc., a hierarchical encoding method, such as discrete cosine transformation, that can improve the image quality step by step from a coarse image to a high quality image and restore it is used. For example, the magazine ``
"Communication Technology" (September 1989 issue), pages 56 to 61 of the article "Progressive build-up display that has entered the practical stage", publication "Television Society Journal" Vol. 43, No. 10 (1989
), in the article "Image Coding Algorithm" on pages 1145 to 1155.

[0005] It is desired to efficiently transmit and restore such hierarchically encoded image data to realize efficient image database searches and the like.

[0006]

2. Description of the Related Art FIG. 7 is an explanatory diagram of the prior art. Figure 7 (
As shown in A), in order to output image data for transmission and restoration from the memory 15 in which each image 1 to 3 encoded by discrete cosine transform or the like is stored, the process is as shown in FIG. 7(B).
As shown in FIG.
After supplying code data up to 5, check whether the next image exists, and if so, select the next image 2,
Code data 2-1 to 2-5 of all layers of the selected image are supplied.

[0007] In this manner, the image is repeatedly transmitted or restored by the transmitter or display unit 14 until no images exist.

Therefore, as shown in FIG. 7(C), when there are three types of image data composed of five layers of code data, all of them are output.

[0009]

[Problems to be Solved by the Invention] However, the prior art has the following problems. In image database searches and the like, it is not always necessary to obtain high-quality images from all layers, and it may be sufficient to obtain images with a certain image quality.

[0010] Even in such a case, the conventional technology outputs coded data for all layers, so it takes time to output coded data of the required image quality for one image.
Transmission time and display output time become longer.

[0011]Furthermore, unless data for all layers of one image are output, the next image data will not be output, so it takes time to output successive images, resulting in a long waiting time.

Therefore, it is an object of the present invention to provide an image data output control method capable of outputting the minimum amount of code data necessary to restore an image of specified image quality and reducing the time required for output. purpose.

[0013]

[Means for Solving the Problems] FIG. 1 is a diagram showing the principle of the present invention. Claim 1 of the present invention provides an image data output control method for outputting encoded data obtained by dividing an original image into a plurality of layers, in which an image quality evaluation value of a restored image restored from encoded data up to each layer is stored. The present invention is characterized in that an image quality storage unit 12 is provided, and code data up to a hierarchy of image quality equal to or higher than a specified image quality is selected and outputted by referring to the image quality storage unit 12.

Claim 2 of the present invention is an image data output control method for outputting encoded data obtained by dividing an original image into a plurality of layers, by adding encoded data of each layer to restore the image. An image quality storage section 12 is provided for storing an image quality improvement value to be improved, and the image quality storage section 12 is referred to, and coded data up to a layer of image quality higher than or equal to a specified image quality is selected and output. do.

According to a third aspect of the present invention, in the first and second aspects, the code data is obtained by dividing the original image into blocks each consisting of a plurality of pixels, and determining the gradation of the plurality of pixels in the block. It is characterized in that the transform coefficients obtained by performing two-dimensional discrete cosine transform on the values are quantized, and the obtained quantized coefficients are encoded.

A fourth aspect of the present invention is characterized in that in the first and second aspects, coded data up to the selected layer is transmitted.

A fifth aspect of the present invention is characterized in that in the first and second aspects, code data up to the selected layer is restored and output.

[0018]

[Operation] According to claim 1 of the present invention, an image quality storage unit 12 is provided for storing image quality evaluation values of restored images restored from encoded data up to each layer, and with reference to the image quality storage unit 12, specified Selects and outputs encoded data up to the layer of image quality higher than the image quality, so it is possible to output the minimum layer of encoded data up to the specified image quality, reducing output time and outputting the next image quickly. .

According to a second aspect of the present invention, an image quality storage section 12 is provided for storing an image quality improvement value improved by restoring an image by adding code data of each layer, and the image quality storage section 12 is referred to. selects and outputs the encoded data up to the layer of image quality higher than the specified image quality, so it is possible to output the encoded data up to the minimum layer up to the specified image quality, shorten the output time, and images can be output quickly.

In claim 3 of the present invention, since encoded data subjected to two-dimensional discrete cosine transformation is used, efficient hierarchical data can be obtained.

[0021] According to claim 4 of the present invention, since code data up to the selected layer is transmitted, the transmission time can be shortened.

According to claim 5 of the present invention, the encoded data up to the selected layer is restored and output, so that the restoration output time can be shortened.

[0023]

[Embodiment] (a) Description of the first embodiment FIG. 2 is an explanatory diagram of the first embodiment of the present invention, showing the configuration of an image data transmission device, and FIG. 3 shows the image quality table of FIG. 2. It is an explanatory diagram. In the figure, 10 is a control data receiving unit, which receives control data such as the image quality of the restored image from the operator on the decoding side, 11 is a control unit, and code selection unit 13
, 13 is an image quality storage unit that controls the image quality storage unit 12, etc., and as shown in FIG.
It stores the SN ratio (referred to as an image quality table) of the image restored from the encoded data up to 5 with respect to the original image. For example, the S/N ratio of the third layer of the first image is
The N ratio is 33.7 dB in this example.

13 is a code selection unit which selects code data in the memory 15 under the control of the control unit 11;
4 is a code data transmission unit that transmits the selected code data, and 15 is a memory that performs two-dimensional discrete cosine transform (DCT) on each original image.
It stores three types of image data 1 to 3 that have been converted into DCT coefficients by sine Transform) and encoded into five layers.

This embodiment shows a case where three types of image data constituted by code data of five layers are selected and the code data is transmitted.

It is assumed that this code data is generated by converting image data into DCT coefficients using discrete cosine transformation.

FIG. 4 is a processing flow diagram of the first embodiment of the present invention. (2) An operator sets the image quality of the restored image (referred to as a control image) to the control unit 11 via the control data receiving unit 10 from a terminal on the decoding side (not shown).

Subsequently, the control data receiving section 10 receives an image transmission instruction signal from the decoding side and outputs a transmission start signal to the control section 11. The control unit 11 selects the first image and instructs the code selection unit 13 to select the first image.

(2) Next, the control unit 11 sets the selected hierarchy to the first hierarchy and instructs the code selection unit 13 to select the first hierarchy.

■Then, the control section 11 controls the image quality storage section 12.
with reference to the image quality value (SN ratio) of the selected layer of the selected image.
Take out.

(2) The control unit 11 compares the extracted image quality value with the specified control image quality, determines whether the extracted image quality value is equal to or higher than the control image quality, and determines whether the control image quality is satisfied. If the control image quality is not satisfied, the control unit 11 sets the selected hierarchy to the next hierarchy and returns to step (2).

■On the other hand, if the control image quality is satisfied, the control section 11 instructs the code selection section 13 to select code data up to the selected layer, and sends the code data up to the selected layer to the code data transmission section 14. Send via.

(2) After the transmission, the control unit 11 checks whether the next image exists, and if so, selects the next image, returns to step (2), and if it does not exist, ends the image transmission.

For example, if the control image quality is 32.0 dB, control is performed by code data up to the third layer for the first image, up to the third layer for the second image, and up to the fourth layer for the third image. It is possible to restore images of image quality or higher, and these are transmitted.

[0035] In this way, it is possible to select and transmit data of the required image quality from the hierarchically structured coded data, thereby shortening the transmission time and speeding up the transmission of the next image. or,
Since you have an image quality table in advance, you can quickly evaluate the image quality.
High-speed determination becomes possible.

(b) Explanation of Second Embodiment FIG. 5 is an explanatory diagram of a second embodiment of the present invention, and shows the configuration of an image data decoding device. In the figure, the same parts as those shown in FIG. 2 are indicated by the same symbols, and 16 is an image restoration unit;
17 is a display unit that decodes the code data selected by the code selection unit 13; 17 is a display unit that displays the restored image; 18 is an input detection unit that detects inputs such as image quality control by the operator; It is.

In this embodiment, an image is restored from hierarchical code data stored in a magnetic disk device, an optical disk device, a semiconductor storage device, etc., and the transmission device in FIG. 2 is replaced with the restoration device. .

FIG. 6 is a process flow diagram of a second embodiment of the present invention. (2) From a terminal (not shown), the operator sets the image quality of the restored image (referred to as control image quality) to the control section 11 via the input detection section 18.

Subsequently, the input detection section 18 receives a restoration instruction signal from the terminal side and outputs a restoration start signal to the control section 11. The control unit 11 selects the first image and instructs the code selection unit 13 to select the first image.

(2) Next, the control unit 11 sets the selected hierarchy to the first hierarchy and instructs the code selection unit 13 to select the first hierarchy.

■Then, the control section 11 controls the image quality storage section 12.
with reference to the image quality value (SN ratio) of the selected layer of the selected image.
Take out.

(2) The control unit 11 compares the extracted image quality value with the designated control image quality, determines whether the extracted image quality value is equal to or higher than the control image quality, and determines whether the control image quality is satisfied. If the control image quality is not satisfied, the control unit 11 sets the selected hierarchy to the next hierarchy and returns to step (3).

■On the other hand, if the control image quality is satisfied, the control section 11 instructs the code selection section 13 to select code data up to the selected layer, and sends the code data up to the selected layer to the restoration section 16. , the image is restored and displayed on the display unit 17.

(2) After the transmission, the control unit 11 checks whether the next image exists, and if so, selects the next image, returns to step (2), and if it does not exist, ends the restoration of the image.

For example, if the control image quality is 32.0 dB, control is performed by code data up to the third layer for the first image, up to the third layer for the second image, and up to the fourth layer for the third image. It is possible to restore images of image quality or higher, and these are restored.

[0046] In this way, it is possible to select and restore data of the required image quality from the hierarchically structured coded data, thereby shortening the restoration time and speeding up the restoration of the next image.

(c) Description of other embodiments In addition to the embodiments described above, the present invention can be modified as follows. ■Although the explanation was given using a transmission device and a restoration device as an example, it may also be applied to an image data receiving device.The explanation was given using an example of three types of image data consisting of five layers of encoded data, but the number of types of images is The number of layers is not limited to this.

(2) Although the control image quality is fixed, it is also possible to specify the control image quality for each image.

■As an image quality evaluation standard, the SN up to each layer
Although the ratio is used, an image improvement value that is improved by adding code data of each layer may also be used. In this case, to obtain the image quality value of a certain layer, the image improvement value of the previous layer is used. need to be added to the value.

(2) An example has been described in which image data is converted into DCT coefficients using discrete cosine transform, but other hierarchical code conversion methods may be used.

(2) Although the SN ratio is used as the image quality evaluation value, it is also possible to use the subjective evaluation value (MOS), mean square error, etc. Although the present invention has been described above with reference to examples, various modifications can be made within the scope of the gist of the present invention, and these are not excluded from the scope of the present invention.

[0052]

[Effects of the Invention] As explained above, according to the present invention,
It has the following effects. ■An image quality storage unit 12 is provided to store the image quality evaluation value of the restored image restored from the encoded data of each layer, and the image quality storage unit 1
2, selects and outputs coded data up to a layer of image quality equal to or higher than the specified image quality, so coded data of the minimum layer up to the specified image quality can be output, reducing output time. .

[0053] Moreover, the next image can be outputted quickly, and image retrieval, etc., can be performed at high speed.

[0054]Furthermore, since an image quality table is provided, judgment can be made quickly.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention.

FIG. 2 is an explanatory diagram of a first embodiment of the present invention.

FIG. 3 is an explanatory diagram of an image quality table according to the first embodiment of the present invention.

FIG. 4 is a process flow diagram of the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a second embodiment of the present invention.

FIG. 6 is a process flow diagram of a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of the prior art.

[Explanation of symbols]

10 Control data receiving section 11 Control section 12 Image quality storage section 13 Code selection section 14 Code data transmitter 15 Memory

Claims (5)

[Claims] Claim 1: An image data output control method that outputs encoded data obtained by dividing an original image into a plurality of layers, wherein an image quality evaluation value of a restored image restored from encoded data up to each layer is stored. An image data output control method comprising: providing a storage section (12); referring to the image quality storage section (12); selecting and outputting encoded data up to a hierarchy of image quality equal to or higher than a specified image quality; . Claim 2: An image data output control method for outputting encoded data obtained by dividing an original image into a plurality of layers, wherein an image quality improvement value is improved by adding encoded data of each layer and restoring the image. Image quality storage unit (1
2), and refers to the image quality storage unit (12) to select and output code data up to a hierarchy of image quality equal to or higher than a specified image quality. 3. The code data is a transformation obtained by dividing the original image into blocks each consisting of a plurality of pixels, and performing a two-dimensional discrete cosine transform on the tone values of the plurality of pixels in each block. 3. The image data output control method according to claim 1, wherein the coefficients are quantized and the obtained quantized coefficients are encoded. 4. The image data output control method according to claim 1, further comprising transmitting encoded data up to the selected layer. 5. Claims 1 and 2, characterized in that encoded data up to the selected layer is restored and output.
image data output control method.