JPH05316343A - Picture reader - Google Patents

Abstract

PURPOSE:To allow a picture reader to solve problems of dispersion in the control and difficulty for making into a large scale circuit integration in a conventional photoelectric conversion reader having an analog system and controlling a dynamic range of an input picture with the analog system, through the adoption of a digital system. CONSTITUTION:The reader is provided with an A/D converter section (b) converting an analog signal 2 subject to photoelectric conversion into digital multi-value data 3, a base density detection section (c) detecting a base density of an original based on the multi-value data 3 outputted from the A/D converter section (b), a character density detection section (d) detecting the character density, and a multi-value multi-value conversion section (e) implementing multi- value/multi-value conversion to data based on the base density and the character density detected by the two detection sections c, d as parameters.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus for correcting input / output characteristics of image information read from a document.

[0002]

2. Description of the Related Art Conventionally, this type of image reading apparatus has controlled the dynamic range of input / output characteristics of image information by an analog method.

[0003]

Since the conventional image reading apparatus described above corrects (controls) the dynamic range of input and output by the analog method, there is a problem that the control varies. There was also a problem that it was difficult to make it.

[0004]

An image reading apparatus of the present invention includes an A / D conversion unit for converting an analog signal of image information read from a document on which an image is drawn into digital multivalued data, and this A / D conversion unit. A base density detection unit that detects the base density of the original document based on the multivalued data output by the D conversion unit;
A character density detection unit that detects character density based on the multi-valued data output by the A / D conversion unit, the base density output by the base detection unit, and the character density output by the character density detection unit. And a dynamic range control unit for performing a correction conversion in a form of linear interpolation between the two, and the dynamic range conversion is performed using the base density and the character density of the input image information as parameters. ..

[0005]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a diagram for explaining the operation of this embodiment.

In the photoelectric converter a, an optical signal 1 reflected from the original
Is input and converted into an analog signal 2. The analog signal 2 photoelectrically converted is converted into a digital signal 8b by the A / D converter b.
A / D converted into it data 3. Next, the A / D converter b
The digital 8-bit data 3 output by is input to the multi-value / multi-value converter e, the base density detector c, and the character density detector d.

Next, the base density detecting section c detects the base density W of the original from the inputted digital 8-bit data 3. The base density W and the character density B of the document detected by the two detection units c and d pass through the signal line 4 (base density W information) and the signal line 5 (character density B information), respectively, and are a multi-value / multi-value conversion unit. is input to e.

In the multi-value / multi-value conversion section e, the input base density W information and character density B information are used as conversion parameters,
The input digital 8-bit data 3 is converted into multi-value / multi-value and is output to the signal line 6 (multi-value / multi-value converted digital 6-bit data).

According to the present invention, the digital dynamic range control is performed by converting the original base density W and the character density B by linear interpolation as shown in FIG. 2 in the multi-value / multi-value conversion. It is something to do.

[0010]

As described above, the image reading apparatus of the present invention detects the base density and the character density of a document by multi-value data obtained by A / D converting the photoelectrically converted analog signal, and detects the detected base density. Since the dynamic range of the input image is controlled digitally by converting multi-value to multi-value between the density and the character density, it is possible to eliminate the control variation, which is the drawback of analog-type dynamic range control. You can Further, since it is a digital system, it can be easily integrated into an LSI.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the present embodiment.

[Explanation of symbols]

 a photoelectric conversion unit b A / D conversion unit c base density detection unit d character density detection unit e multi-value / multi-value conversion unit

Claims (1)

[Claims] 1. An A for converting an analog signal of image information read from a document on which an image is drawn into digital multi-valued data.
A / D conversion unit, a base density detection unit that detects the base density of the original document based on the multivalued data output by the A / D conversion unit, and a character density based on the multivalued data output by the A / D conversion unit. And a dynamic range control for performing correction conversion by linearly interpolating between the base density output by the base detection unit and the character density output by the character density detection unit. And an image reading device for converting a dynamic range using the base density and the character density of the input image information as parameters.