JPH04320157A - Picture data processor - Google Patents

Abstract

PURPOSE:To improve the processing speed by providing a memory fetching an interleaved picture data obtained by a magnification conversion circuit and inputting the interleaved picture data to a discrimination circuit as a representative point of the discrimination circuit on the processor. CONSTITUTION:An input picture from a line sensor 14 is corrected by a correction circuit 21 and subject to magnification, reduction, picture element density conversion by a magnification conversion circuit 32 and stored tentatively in a memory 42. The memory 42 acts like a buffer for a representative point for the picture density measurement and an edge detection at preliminary scanning after the picture data obtained by preliminary scanning is interleaved at the reduction processing of the circuit 32. Moreover, the circuit 32 implements statistical processing and uses a numeral to extract the representative point, and the memory 42 takes a timing between a CPU 44 and a picture bus to generate a correction parameter and a histogram. Thus, the capacity of the memory 42 is considerably reduced to quicken the processing speed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data processing apparatus, and more particularly to an image data processing apparatus that reads an image using a sensor, digitizes it, and processes it.

0002

2. Description of the Related Art Conventionally, image data processing devices have been used in image reading devices, image reading/recording devices, etc.
After an original image is read using a photomultiplier), an image pickup tube, and a solid-state image pickup device such as a CCD, various image processing is performed on the image data signal. The image signal that has undergone image processing is sent to a suitable image recording device or image reading and recording device, where it is used to record on a recording material such as a photosensitive material or a photoreceptor.

For example, after reading a continuous tone image document such as a photograph or film using a CCD and converting it into an electrical signal,
In an image reading/recording apparatus such as a scanner that produces a printing film having a halftone image, as shown in FIG. After performing analog correction such as gain correction, A/D conversion is performed, and correction circuit section 103 performs CCD correction such as shading correction and dark correction for each pixel, and then logarithmic conversion and gradation conversion. , smoothing and magnification conversion are performed, and in the halftone dot generation unit 107, after each processing such as sharpening, a halftone dot image signal is obtained, and this halftone dot image signal is used as a light emission signal of a light source in an image recording device. The halftone dot image is reproduced on the film by modulating the

[0004] In modulation processing devices such as image processing devices and image recording devices (hereinafter collectively referred to as image data processing devices), various image processing parameters such as document density and document size are When determining the image processing parameters, a scanner scans the surface of the document in advance, reads the document image, and determines the image processing parameters.
Image data such as density values are often taken into a determination circuit provided inside the device. For example, in the apparatus shown in FIG. 5, during prescanning in which an image is scanned in advance and image processing parameters are set, the thinning processing unit 105 thins out the image data, and the thinned image data is temporarily stored in the line memory. The information is stored and various image processing parameters are determined under the control of the CPU 111. In this case, capturing all pixel data and using it as judgment data would take a long time to process and the circuit would be large-scale.
Representative points were extracted and the characteristics of the entire image were estimated through statistical processing.

[0005] Conventionally, representative points have been extracted using two methods: (1) selecting the one to be retrieved from an image once stored in memory; and (2) using a special representative point extraction circuit to extract the image to be written into memory. A selective method was used.

However, the method of once importing the data into memory has the disadvantage that the memory capacity becomes large, the processing time required for this processing increases, and the overall processing speed becomes slow. Furthermore, the method using a special circuit has the disadvantage that it prevents miniaturization of the entire circuit.

[0007]

[Problems to be Solved by the Invention] The present invention solves the above problems and realizes representative point extraction with a simpler circuit configuration.
Another object of the present invention is to provide an image data processing device that reduces processing time required for processing and improves processing speed.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a magnification conversion circuit that extracts and interpolates image data according to the magnification, and a magnification conversion circuit that extracts and interpolates image data according to the magnification, and provides image data or pixel data for determining image processing parameters. In the image data processing device, the image data processing device is provided with a memory that takes in the thinned image data obtained by the magnification conversion circuit and inputs this thinned image data to the judgment circuit as a representative point of the judgment circuit. An image data processing device with features is provided.

[0009]

[Operation] The present invention is a device for scanning image data in advance (prescanning) and determining image processing parameters, and was proposed to improve the speed of prescanning compared to conventional methods. .

That is, according to the present invention, a part of the function of the magnification conversion circuit that extracts and interpolates image data according to the magnification is utilized, for example, for determining the image density distribution on the document surface. A memory is provided between the conversion circuit and the determination circuit, and thinned image data obtained by thinning out the image data, which is part of the statistical processing function of the magnification conversion circuit, is taken into the memory and temporarily stored as a representative point of the image density distribution. , various processes can be performed by, for example, a central control unit (CPU) and sent to the determination circuit.

[0011] Therefore, by using image data obtained by statistical processing of a magnification conversion circuit already incorporated in an image data processing device as a representative point, it is not possible to import all image data or all pixel data as in the conventional case. The processing speed is faster than when the judgment data is used in The memory can be small because it is small scale and there is no need to store images over some or all of the image lines. Furthermore, this device is particularly effective when the image bus and CPU bus are separate.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the image data processing apparatus according to the present invention will be described below in more detail with reference to the accompanying drawings.

FIG. 1 shows the entire image data processing apparatus according to the present invention. Reference numeral 10 indicates an image reading and recording device to which the image data processing device is applied. In this image reading/recording apparatus 10, a continuous gradation image of a document G is converted into an electrical signal and then reproduced on a film F as a halftone gradation image.

That is, the document G is configured to be conveyed in the sub-scanning direction in the direction of the arrow A by a conveyance means (not shown), and the continuous tone image of the document G is transmitted through the condensing optical system 12 to the photoelectric conversion means. Main scanning is performed in the direction of arrow B by a line sensor 14 made of a certain CCD. The continuous tone image photoelectrically converted and amplified by the line sensor 14 is converted into an A/D image based on the main scanning clock Φ from the clock generator 16.
After being converted into a digital image signal S by the converter 18,
The image data is supplied to an image processing section 20 consisting of an image data processing device of the present invention.

In the image processing section 20, the clock generator 16
After performing line sensor gain correction, offset correction, etc. on the digital image signal S based on the clock signal from the line sensor, the line sensor performs defective pixel correction, dark time correction, logarithmic conversion processing, shading correction, gradation conversion processing, It is subjected to image processing such as magnification conversion processing, averaging processing, sharpening processing, and hatching processing, and is output to the image recording unit 22 as a binarized halftone image signal R. The image recording unit 22 records a halftone image by electro-optically converting the halftone image signal R into an optical signal such as a laser beam and guiding it onto the film F.

FIG. 2 shows the configuration of the image processing section 20 of FIG. 1. In this case, the image processing unit 20 first processes the correction circuit 21 to which image data is sequentially flowing through the image bus.
, the magnification conversion circuit 32, the image processing circuit 34, and the CPU 44 and ROM that exchange information via the CPU bus.
46, RAM 48, correction circuit 21, magnification conversion circuit 32, image processing circuit 34, CPU 44, ROM
46 and RAM 48 are connected to each other via a bus to perform various image processing.

The correction circuit 21, as shown in FIG.
A preprocessing circuit 24, a CCD correction circuit 26, and a gradation correction circuit 28 are provided. The image processing circuit 34 also includes a determination circuit 36, an averaging processing (unsharp processing) circuit 30,
A sharpening processing circuit 38 and a shading processing circuit 40 are provided.

The preprocessing circuit 24 uses the dark mask image signal to eliminate noise components associated with fluctuations in offset errors such as temperature drift and voltage fluctuations of analog elements such as line sensors, amplifiers, and A/D converters. For example, when the image signal level in the dark varies over a plurality of scanning lines, the offset error is compensated for each line to stabilize the signal.

The CCD correction circuit 26 includes a dark correction circuit that corrects base non-uniformity of each pixel (which exists even when no light is incident), a logarithmic conversion circuit that logarithmically converts the image signal,
It also performs shading correction to compensate for non-uniformity in the output voltage with respect to the amount of incident light (including non-uniformity in illumination) due to variations in each pixel of the line sensor 14, which is a solid-state image sensor. For example, if the document image density is the same, the image data (image signal) is the same.

The gradation correction circuit 28 shown in FIG. 3 is a circuit that converts into an image signal corresponding to gradation characteristics (exposure-density characteristics), and the averaging circuit 30 converts input image data and peripheral pixel data. This is a circuit that aims to reduce the noise in the image data signal by averaging the data.

The magnification conversion circuit 32 shown in FIG. 2 is a circuit that converts the pixel density in the main scanning direction. For example, compression/expansion of digital data is done according to the principle of changing the sampling period and always outputting at the same period. A clock inhibit signal with a period thinned out by a specific number of pulses is read from the register, and written to the register via an attached counter and logic gate, thereby enlarging, reducing, and converting the pixel density.

The determination circuit 36 shown in FIG. 4 includes a determination circuit 36 that determines the rate at which the magnification-converted density data such as contrast changes according to a predetermined criterion, and determines whether or not to perform averaging. It is used to convert signals for image recording.

The sharpening processing circuit 38 emphasizes the edges such as the outline of the image and performs sharpening processing. For example, it subtracts a constant times the smoothed image from the original image data, and then performs the unsharpening process. It performs sharp masking to increase image sharpness and emphasize edges.

The halftone processing circuit 40 characterizes a halftone image signal from the image density signal, and this halftone image signal is used to subject the image density to area modulation in accordance with a desired angle and number of lines. This halftone image signal is output to the image recording section 22.

In the circuit configuration described above, a memory (F
IFO) 42 is installed. For example, the memory 42 uses the image data thinning function of the magnification conversion circuit 32 to pre-scan the image data obtained by pre-scanning the document surface in advance, and converts the thinned-out image data after the image data has been thinned into a pre-scan, for example. It serves as a buffer for temporary storage and as a representative point for image density measurement and end detection. Therefore, the memory 42 has a normal line memory of 10,000 to 30,000 b.
However, since the image data is reduced to about 1/4 to 1/20 by the processing after thinning, it is only necessary to prepare data of about 500 to 8000 bytes. In this case, the magnification conversion circuit 32 operates as a thinning circuit for detecting an image density value or detecting an end of an image during pre-scanning, which is different from the normal document surface reading operation, for example.

The magnification conversion circuit 32 not only extracts representative points but also performs statistical processing at the same time, and the statistical processing includes averaging and weighted averaging. Representative points can be extracted using this value. The memory 42 is for timing the CPU 44 side and the image bus side, and it becomes possible to create correction parameters and histograms in real time using this image data.

The thinned image data temporarily stored in the memory 42 can be directly or
After being stored in the M48, various calculations and calculations are performed at predetermined timings. For example, the concentration value is fed back to the correction circuit 21 to correct it to a predetermined concentration, or to the determination circuit 36. The document is sent and processing for detecting the end of the document surface is performed.

For example, when performing automatic density measurement, the correction circuit section 21 is configured to create a density histogram from representative points, calculate the density distribution of the original, and perform density correction on the image data using the calculated data. Give data.

For example, when performing automatic end detection of a document, the magnification conversion circuit section 32 calculates the average value of image density data for one line while reading the document, and monitors the average value from time to time. If the rate of change in the density data exceeds a certain threshold value, it is determined that the end point has been reached.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be modified and modified in various ways.

[0031]

According to the present invention, part of the function of the magnification conversion circuit that extracts and interpolates image data according to the magnification is used, for example, to determine the image density distribution on the surface of the document. A memory is provided between the conversion circuit and the determination circuit, and thinned image data obtained by thinning out the image data, which is part of the statistical processing function of the magnification conversion circuit, is taken into the memory and temporarily stored as a representative point of the image density distribution. , various processes can be performed by, for example, a central control unit (CPU) and sent to the determination circuit. therefore,
By using the compressed image data obtained through statistical processing of the magnification conversion circuit already built into the image data processing device as a representative point, it is possible to take in all image data or all pixel data and make judgments as in the past. The processing speed is faster than when processing data, and the circuit size and memory capacity are smaller, for example, 1/2 compared to line memory.
Because it only requires 4 to 1/20 of the memory,
The circuitry can be small in scale, and the memory can be small since it is not necessary to store images for an entire image line. Furthermore, this device is particularly effective when the image bus and CPU bus are separate.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an image reading and recording device to which an image data processing device according to the present invention is applied.

FIG. 2 is a block diagram showing an embodiment of the image processing section of the image data processing device of the present invention.

FIG. 3 is a block diagram showing an example of a correction circuit section of the image processing section of the image data processing device of the present invention.

FIG. 4 is a block diagram showing an example of an image recording circuit section of the image processing section of the image data processing device of the present invention.

FIG. 5 is a block diagram showing a control section of a conventional image data processing device.

[Explanation of symbols]

10 Image reading and recording device 14 Line sensor (CCD) 20 Image processing section 21 Correction circuit 32 Magnification conversion circuit 34 Image recording circuit 36 Judgment circuit

Claims (1)

[Claims] 1. An image data processing device comprising: a magnification conversion circuit that extracts and interpolates image data according to a magnification; and a determination circuit that takes in pixel data to determine image processing parameters; An image data processing device comprising a memory for capturing the obtained thinned image data and inputting the thinned image data to a determination circuit as a representative point of the determination circuit.