JPH01284068A - Picture input device - Google Patents

Abstract

PURPOSE:To obtain a picture data with high picture quality while bit noise is eliminated by devising the device such that a memory storing a location data of a bit noise corresponding to each picture element of an image sensor is used and no sampling is applied by a sampling means at the picture element position corresponding to the bit noise based on the memory. CONSTITUTION:A position data SD of bit noise is inputted from a memory 4 to a clock circuit 3A and a correction signal KSI is inputted to a phase control circuit 6A at the picture element position corresponding to the bit noise and the phase control circuit 5A inputs a correction sampling signal SSI to a sample-and-hold circuit 6 so as not to output a clock signal KS of the timing in the input of the correction signal KSI. That is, a picture signal GS of the bit noise is not sampled and the value holding by the sampling of the data of the preceding picture element is outputted. Thus, the effect of the bit noise is eliminated from the output signal.

Description

[Detailed Description of the Invention] Purpose of the Invention; (Industrial Application Field) This invention aims to remove bit noise fixedly generated from pixels of an image sensor such as C(:D) by sampling correction. The present invention relates to an image input device.

(Prior Art) FIG. 3 shows a block configuration of a conventional general image input device.

In this image input device, an image lO of a document or the like is optically read by an image sensor (for example, a line sensor) 2 such as CC [1] via an optical system 1 such as a lens. In this case, a lock signal KS as shown in FIG. 2(B) is input from the clock circuit 3 to the image sensor 2, and an image signal GS synchronized with the lock signal S as shown in FIG. is output. on the other hand,
The clock signal S is also input to the phase control circuit 5, and the second
As shown in Figure (B), the sampling signal S5 shifted by a predetermined phase is input to the sample and hold circuit 6, and the signal components output corresponding to each pixel of the image signal GS are sampled and held. ing. Then, the hold value corresponding to each pixel of the sample hold circuit 6 is output as image data GO.

(Problem to be Solved by the Invention) However, the number of pixels in the image sensor 2 is enormous, and due to manufacturing variations, certain pixels may always output a signal that is slightly higher or lower than the surrounding pixels. Yes, even if the uniform density image 10 is read, bit noises NSI and NS2 as shown in FIG. 2 (8) are present on the image data GS.
will occur. Then, the image signal GS with the bit noises NSI and NS2 is output to the sample and hold circuit 6.
, the image data GD with noise BNI and BN2 as shown in FIG. 3(C) is output as is. In this case, the magnitude of bit noise is always constant regardless of the density (brightness) of the image IO, so even if the signal level changes from high to low as in GD8 to GDC, the noise BNl
The difference α between the value at each level of BN2 and the true value is the same.

When an image is reproduced based on the image data GD output in this way, bit noise always occurs from the same pixel of the image sensor 2, so in the case of a line sensor, vertical streak-like unevenness appears in the reproduced image. There is a drawback. Moreover, since the error is always output with the same level difference regardless of the density, the noise BNI and B on the image data GD are
It is difficult to eliminate N2 using conventional sensitivity variation correction devices (bright area correction devices).

This invention was made from the above-mentioned circumstances,
An object of the present invention is to provide an image input device that can remove bit noise generated from fixed pixels of an image sensor and obtain high-quality image data.

Structure of the Invention; (Means for Solving the Problems) The present invention relates to an image input device that outputs image data by sampling an image signal read by an image sensor using a sampling means. The above object includes a memory in which bit noise position data corresponding to each pixel of the image sensor is stored in advance;
This is achieved by providing a sampling control means that prevents the sampling means from sampling at the pixel position corresponding to the bit noise based on this memory, and outputs the sampling signal of the adjacent previous pixel as it is.

(Function) The image input device of the present invention measures bit noise position data corresponding to each pixel position of the image sensor and stores it in advance in a memory, and based on the position data, the sampling control means (clock circuit 9 By inputting the corrected sampling signal obtained by driving the oscilloscope control circuit into the sampling means and sampling the image signal from the image sensor, high-quality image data from which bit noise has been removed is obtained. . In other words, since the sampling value of the previous pixel is output without sampling at a pixel position corresponding to bit noise of the image sensor, image input can be performed without being affected by bit noise.

(Embodiment) FIG. S1 shows a block configuration of an image input device which is an embodiment of the present invention, and the same members as those in FIG. 3 will be described with the same reference numerals.

In the image input device of the present invention, the conventional device is provided with a memory 4 for measuring and storing bit noise position data SD corresponding to each pixel position of the image sensor 2 in advance. Further, the clock circuit 3A is configured to output not only the lock signal S but also the correction signal Sl based on the position data SD stored in the memory 4, as in the conventional case, and the phase control circuit 5^ A corrected sampling signal SS1 based on the corrected signal S1 is generated and inputted to the sample hold circuit 6. Note that the memory 4 is configured to store bit noise pixel position data SD obtained by measuring pixel data of the image sensor 2 in advance.

Next, the operation of such an image input device will be explained.

As in the case of FIG. 3, the image lO is read by the image sensor 2 via the optical system 1, and the image signal GS is input from the image sensor 2 to the sample and hold circuit 6. In this invention, the bit noise position data SD is input from the memory 4 to the clock circuit 3^, and the bit noise NS
When Sl is input to the phase control circuit 5A as a correction signal as shown in FIG. 2(D) at the pixel position corresponding to I and NS2, and St is input as a correction signal to the phase control circuit 5, the timing A corrected sampling signal 551 as shown in FIG. 3E, in which the clock signal KS is not output, is input to the sample hold circuit 6. In other words, in this example, the second
For the correction signal KSI shown in the figure (D) corresponding to the bit noises NSI and NS2 in the figure (A), the correction sampling signal SS1 shown in the figure (E) is inputted to the sample hold circuit 6, and the bit noise NSI Sampling of the image signal GS of NS2 and NS2 is not performed, and the value held by sampling the data of the previous pixel is output. Thereby, the influence of bit noise is removed from the output signal. Therefore, the image data GDl output from the sample hold circuit 6 has bit noise BN! as shown in FIG. and BN2 are removed, resulting in a uniform image, and when the image is read and input, the image quality is high.

Effects of the Invention: According to the image input device of the present invention, there is an advantage that bit noise generated from pixels of an image sensor, which has been difficult in the past, can be completely removed and high-quality image data can be obtained.

Moreover, it has the advantage that the device configuration is simple and the cost is low.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of an image input device which is an embodiment of the present invention, FIGS. 2(A) to (F) are time charts showing examples of signal waveforms in the image input device, and FIG. 3 is a conventional general 1 is a block configuration diagram showing a typical image input device. 1...Optical system, 2...Image sensor, 3.3A・
...Clock circuit, 4...Memory, 5,5A...Phase control circuit, 6...Sample hold circuit, 10...
·image.

Claims (1)

[Claims] 1. In an image input device that outputs image data by sampling an image signal read by an image sensor with a sampling means, position data of bit noise corresponding to each pixel of the image sensor is stored in advance. and sampling control means for preventing the sampling means from sampling at the pixel position corresponding to the bit noise and outputting the sampling signal of the adjacent previous pixel as it is based on the memory. An image input device characterized by: