JPH05268423A - Scanner - Google Patents

Abstract

PURPOSE:To obtain a picture input with high quality efficiently by applying main scanning to picture data of an original with an optimum luminous quantity calculated by an optimum luminous quantity calculation means so as to obtain an input light in matching with a read range of a light receiving element. CONSTITUTION:A scanner main body 1 applies preliminary scanning to picture data of an original with rough resolution and inputs the result to a controller 4, and an arithmetic operation device 3 calculates the entire histogram from data linear to the luminous quantity. Simultaneously the arithmetic operation device 3 calculates statistic data such as mean value, variance and standard deviation of picture data. Then histograms of picture data of all kinds of originals, statistic data and luminous quantity optimum to each original are stored in advance in a storage device 2 as a database. Then data closest among data stored based on the histogram and the statistic data of the calculated original data are selected as an optimum luminous quantity. The picture data are subject to main scanning by the luminous quantity. Thus, a picture input with high quality is efficiently obtained independently of the kind of the original.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner device used for inputting image data of an original, and in particular, regardless of the type of the original, an input light that always matches the reading range of the light receiving element is obtained and high quality is obtained. The present invention relates to a scanner device capable of efficiently performing various image inputs.

[0002]

2. Description of the Related Art Recently, scanner devices have been widely used in the field of color printing due to the dramatic progress in electronics technology and image processing technology. This scanner device is an extremely effective means for inputting high-definition image data of various originals. That is, the scanner device takes out the light and shade and color components of a color document as very small pixels, converts them into electric signals, and electronically performs various image processing operations to correct the colors and gradations (tones). It records (outputs) halftone film (negative and positive).

By the way, in this type of scanner device, in order to efficiently input a high-quality image, the type of document (high key (the document is overexposed because it is overexposed) ), Low-key items (the original is dark due to insufficient exposure), etc.) (various settings (highlight / shadow settings, tone curve selection or adjustment, etc.))
Are doing. That is, this is because signal processing is performed so that optimum halftone dot reproduction can be performed from the original reading signal.

However, these signal processings are CC
Since it sets what kind of halftone dot is to be output with respect to the signal output from the light receiving element such as D, a signal outside the reading range of the light receiving element is set for a bright original or a dark original. Is input, all of these signals become constant (or output 0), and it becomes impossible to reproduce the change in gradation.

This point will be described with reference to FIG.

That is, it is assumed that the readable range of the light receiving element is, for example, density 0 to 2. Here, if the density distribution is about 0.2 (highlight) to 2.0 (shadow), it is conceivable to set the tone curve as shown in FIG. In this case, gradation can be reproduced with halftone dots in almost the entire density range of the original.

On the other hand, if the density distribution is about 0.5 (highlight) to 2.6 (shadow), the setting of the tone curve is as shown in FIG. 4B. Can be considered. However, in this case,
Even if data other than the readable range 0 to 2 of the light receiving element (data of 2 or more) is input, the output value becomes the same value in a saturated state, and it becomes impossible to read the gradation. Will end up.

[0008]

As described above, in the conventional scanner device, when the reading range of the light receiving element is narrow, an effective signal outside the reading range cannot be read depending on the type of the original. There was a problem.

The present invention has been made in order to solve the above-mentioned problem, and regardless of the type of the original, the input light that always matches the reading range of the light receiving element is obtained, and high-quality image input is efficiently performed. It is an object of the present invention to provide a highly reliable scanner device that can be performed in a specific manner.

[0010]

In order to achieve the above object, according to the present invention, in a scanner device used for inputting image data of a document, a prescan unit for prescanning the image data of the document and a press. Based on the characteristic amount calculation means for calculating the characteristic amount relating to the density distribution of the image data pre-scanned by the scanning means, and the characteristic amount calculated by the characteristic amount calculation means It comprises an optimum light amount calculation means for calculating the light amount, and a main scanning means for main scanning the image data of the original with the optimum light amount calculated by the optimum light amount calculation means.

Here, in particular, as the feature amount calculating means, a histogram, an average, a variance or a standard deviation relating to the density distribution of the pre-scanned image data is calculated.

Further, as the prescanning means, red (R), green (G) and blue (B) of image data of an original document are provided.
Only one color of each color component or only one color by a special filter for prescan is read.

Further, as the above prescan means,
Pre-scanning is performed at a resolution that is coarser than the reading resolution during main scanning.

[0014]

Therefore, in the scanner device of the present invention, the image data of the original is prescanned, and the characteristic amount relating to the density distribution of the prescanned image data is calculated. Then, from this calculated feature amount, the most appropriate light amount for the main scan for the image data of the document is calculated, and the main scan of the image data of the document is performed with this optimum light amount.

As a result, since the scanning light quantity can be changed for each density of the original, the reading can be carried out within the readable range of the light receiving element, and the readable range of the light receiving element is effectively utilized to obtain an extremely high quality. It is possible to efficiently perform high-quality image input.

[0016]

First, the concept of the present invention will be described with reference to FIG.

In FIG. 3, assuming that the input light quantity is I _O , the transmitted light quantity is I, and the transmittance is T, the relationship of T = I / I _O or I = I _O · T is established.

In this case, the range of light amount that can be received by the light receiving element (CCD or the like) is 1.0 × 10 ^−0.2 · t ≧ I ≧ 1.0 × 10 ^−2.8 · t
(T is a constant). When the standard distribution range of the transmittance is 1.0 × 10 ^−0.2 ≧ T ≧ 1.0 × 10 ^−2.8 , the input light quantity I _O is I _O = 1.0 × t It becomes possible for the light receiving element to receive the entire transmittance region within the range of the light amount that can be received by the light receiving element.

However, when the type of the original is changed and it becomes dark (low key) as a whole, the distribution range of the transmittance becomes 1.0 × 10 ^−0.4 ≧ T ≧ 1.0 × 10 ^−3.0. If, when the amount of input light to the fixed remain I _O = 1.0 × t, the distribution range of the amount of transmitted light ^{is, 1.0 × 10 -0.4 · t ≧} I ≧ 1.0 × 10 -3.0 · t becomes, The range of 1.0 × 10 ^−2.8 · t ≧ I ≧ 1.0 × 10 ^−3.0 · t in the dark portion is out of the ^receivable light amount range.

Therefore, if the input light quantity is variable and I _O = 1.0 × 10 ² × t, the distribution range of the transmitted light quantity is 1.0 × 10 ^−0.2 · t ≧ I ≧ 1.0 × 10 ^{− It} becomes ^2.8t , and light can be received in the entire transmittance range of the original.

Therefore, according to the present invention, the most appropriate light quantity for scanning is calculated according to the type of the original, and the original is scanned with this optimum light quantity, that is, the scan light quantity is changed for each density of the original. ..

An embodiment of the present invention based on the above concept will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a hardware configuration example of a scanner device according to the present invention. That is, as shown in FIG. 1, the scanner device of this embodiment is composed of a scanner device main body 1, a storage device 2, an arithmetic device 3, and a control device 4.

Here, the scanner device main body 1 performs a prescan function for prescanning image data of an original document (not shown) at a coarse resolution in advance, performs a main scan of the image data of the original document, and corrects the color of the input data. It has a function of performing gradation correction, adjustment of gray balance, etc., and outputting to an output target (for example, a layout scanner or the like), and a function of setting the light amount at the time of main scanning to a designated value.

Further, the storage device 2 is the scanner device main body 1
Image data input by, light amount data for reference,
It is for storing statistical data and the like calculated by the arithmetic unit 3.

Further, the arithmetic unit 3 calculates the characteristic amount relating to the density distribution of the image data prescanned by the scanner main body 1, and calculates the characteristic amount based on the characteristic amount calculated by the characteristic amount calculating function. Having the function of setting the optimum light amount calculation function for calculating the most suitable light amount in the main scan for the image data of the image and the optimum light amount calculated by the optimum light amount calculation function as the light amount in the main scan in the scanner device body 1. Is.

Further, the control device 4 controls the scanner device body 1, the storage device 2, the arithmetic device 3 and the like.

Next, the operation of the scanner device of this embodiment having the above-described structure will be described with reference to the flow chart shown in FIG.

In FIG. 1, first, image data of a document to be scanned is pre-scanned by a scanner device main body 1 at a coarse resolution with a reference light amount and the data is input (data is linear to the light amount).

Next, from the data pre-scanned and linear to the light amount, a histogram of the entire image (representing the filing frequency of pixels with respect to the density value) is calculated by the arithmetic unit 3 as a characteristic amount relating to the density distribution of the image data. To calculate. At the same time, statistical data necessary for statistical analysis such as average, variance, or standard deviation of image data is also calculated.

Next, from the histogram and the statistical data calculated above, the arithmetic unit 3 calculates the most appropriate light quantity during the main scan for the image data of the document. (In this case, it is preferable that both the highlight and the shadow are within the reading range of the light receiving element, but even if both cannot be controlled within the range, the image data of the original is determined from the average, variance or standard deviation. The amount of light corresponding to the density distribution of is set) The optimum amount of light during this main scan is calculated as follows, for example. That is, the histogram, average, variance, or standard deviation of image data of all types (“high key”, “standard”, and “low key” of different degrees) of originals and the optimum light amount for the originals are determined. Then, it is stored in the storage device 2 as a database. Then, based on the histogram of the image data of the original document calculated above, the average, the variance or the standard deviation,
From the data in the database, which one has the closest tendency is selected, and the light quantity corresponding to it is determined as the optimum light quantity.

In this case, the more data points are stored in the database, the more accurate the light quantity can be calculated. Further, when the number of data points is small, there is also a method of calculating the light quantity by performing an interpolation calculation from the statistical data obtained by the prescan and the data stored in the database. In addition, the reference light amount at the time of pre-scan is obtained by scanning the image data of the original,
It should be the same as the amount of light used when creating statistical data in the database.

Next, from the relationship between the optimum light amount calculated above and the reference light amount, the highlight measured with the reference light amount,
Calculate how the density value of the shadow changes apparently, and set the highlight value and shadow density value at the optimum light amount (or perform another pre-scan at the optimum light amount and highlight it again. , Make shadow settings). In this case, the lowest or highest sum or average of the R, G, and B digital data of the image input of the original is defined as the highlight and shadow, respectively.

Next, the disassembling condition of the scanner apparatus main body 1 is set based on the above-mentioned respective data (highlight, shadow, curve).

Finally, by changing the light amount to the optimum light amount by the scanner main body 1, the main image data of the original is scanned to read the image data, and the input data is subjected to color correction, gradation correction, and gray balance. Various treatments such as
Output to an output target such as a layout scanner.

In the above, the scanner device main body 1
As a method for adjusting the light amount at the time of main scanning on the side, for example, the following method can be considered. However, the scan time is constant.

(A) A method of using a light source capable of changing the amount of light as a light source.

(B) In the optical system from the light source to the original, the distance between the two points is changed by the position of the lens or the like to adjust the amount of light hitting the original while keeping the amount of light from the light source constant.

(C) Several kinds of filters having different densities for adjusting the light quantity are prepared between the light source and the original, and by changing the filters, the light quantity that hits the original with the light quantity of the light source kept constant can be obtained. How to adjust.

As described above, the scanner device of this embodiment performs the prescan function of prescanning the image data of the original document with a coarse resolution, the main scan of the image data of the original document, and the color of the input data. Amendment,
Scanner device main body 1 having a function of performing gradation correction, gray balance, etc., and outputting to an output target (layout scanner, etc.), and a function of setting the light amount at the time of main scan to a specified value, and scanner device main body 1 A storage device 2 for storing image data input by the CPU, reference light amount data, statistical data calculated by the arithmetic device 3, and the like.
And a feature amount calculation function for calculating a feature amount relating to the density distribution of the image data pre-scanned by the scanner main body 1, and a feature amount calculated by the feature amount calculation function, the most suitable book for the image data of the document. An optimum light amount calculation function for calculating the light amount at the time of scanning, and an arithmetic unit 3 having a function of setting the optimum light amount calculated by the optimum light amount calculation function as the light amount at the main scan in the scanner device main body 1 and the scanner device main body 1 , A storage device 2, and a control device 4 for controlling the arithmetic device 3 and the like.

Therefore, the image data of the document is prescanned in advance, the characteristic amount relating to the density distribution of the prescanned image data is calculated, and the light amount in the main scan most suitable for the image data of the document is calculated from this characteristic amount. Since the main scanning of the image data of the original is performed with the calculated optimum light amount, the scan light amount can be changed for each density of the original.

As a result, the same effect as when the tone curve is shifted can be obtained, and the readable density range of the light receiving element can be changed. , Regardless of the type of original such as a low key, it is possible to obtain input light that always matches the reading range of the light receiving element, and efficiently perform extremely high quality image input.

In the above embodiment, the case where the histogram, the average, the variance or the standard deviation of the prescanned image data is calculated as the characteristic amount has been described, but the present invention is not limited to this.

Further, in the above-mentioned embodiment, when the prescan is carried out, the following technique is taken,
It is possible to shorten the scan time.

(A) Only one of red (R), green (G), and blue (B), or a special filter for prescan (for example, one having a spectral characteristic similar to visual sensitivity) Read only one color.

(B) The prescan is performed with a minimum necessary resolution that is coarser than that in the main scan for calculating the feature amount (histogram). In this case, the minimum required resolution is determined in consideration of two items, that is, the prescan time, and statistically how much the same data as the original data can be obtained.

[0047]

As described above, according to the present invention, in the scanner device used for inputting the image data of the document, the prescan unit for prescanning the image data of the document and the prescan by the prescan unit. Optimum for calculating the most appropriate light quantity during the main scan for the image data of the document based on the characteristic amount calculation means for calculating the characteristic amount relating to the density distribution of the image data thus obtained and the characteristic amount calculated by the characteristic amount calculation means. Since the light amount calculation means and the main scanning means for performing the main scan of the image data of the document with the optimum light amount calculated by the optimum light amount calculation means are provided, the reading range of the light receiving element is always matched regardless of the type of the document. It is possible to provide an extremely reliable scanner device that can obtain high-quality image input by efficiently obtaining the input light.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a scanner device according to the present invention.

FIG. 2 is a flow chart for explaining the operation in the same embodiment.

FIG. 3 is a schematic diagram for explaining the concept of the present invention.

FIG. 4 is a characteristic diagram for explaining a tone curve setting method based on highlight and shadow values.

[Explanation of symbols]

1 ... Scanner device main body, 2 ... Storage device, 3 ... Arithmetic device,
4 ... Control device.

Claims (4)

[Claims] 1. A scanner device used for inputting image data of a document, characterized by prescan means for prescanning the image data of the document, and density distribution of image data prescanned by the prescan means. A characteristic amount calculating means for calculating an amount, an optimum light amount calculating means for calculating a light amount in the main scan most suitable for the image data of the document based on the characteristic amount calculated by the characteristic amount calculating means, A scanner device, comprising: a main scanning unit that performs a main scan of the image data of the document with the optimum light amount calculated by the light amount calculating unit. 2. The scanner device according to claim 1, wherein the feature amount calculation means is configured to calculate a histogram, an average, a variance, or a standard deviation regarding a density distribution of pre-scanned image data. .. 3. The prescan means is only one of the red (R), green (G), and blue (B) color components of the image data of the document, or one color by a special filter for prescan. The scanner device according to claim 1, wherein only the minute is read. 4. The scanner device according to claim 1, wherein the pre-scanning unit is configured to perform a pre-scan at a resolution coarser than a reading resolution at the time of main scanning.