JP3087845B2 - Digital image processing method for reading an original image with a scanner and enlarging and printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a digital image processing method, and more particularly to a digital image processing method for reading an original image with a scanner and enlarging and printing it.

[0002]

2. Description of the Related Art As an example of a system for color printing of a color original image, a personal computer in which an image processing program (generally called "photo retouching software") is set up, and an RGB3 having a CCD line sensor. A time-scanning flat scanner and a color inkjet printer or a color laser printer are used.

The data processing in the process from reading of an original image to printing by the image processing program generally follows the following flow. The personal computer controls the scanner to read the original image. The image data transferred from the scanner is developed in the video RAM as bitmap image data. Further, the image data is converted into print data. Then, the printer is controlled based on the print data and printed out. When an original image is enlarged and printed on an area gradation type color printer such as an ink jet printer with high image quality, the reading conditions and printing conditions of the original image are determined by reading the original image at a resolution as high as possible and selecting the maximum printing. It is set to print out at the resolution.

[0004] When converting image data into print data, a personal computer performs complicated processing such as resolution conversion processing and binarization processing. The resolution conversion is a process of appropriately increasing or decreasing the number of pixels included in the image data so that a certain pixel of the original image corresponds to a certain pixel of the print image in order to make the difference between the reading resolution and the printing resolution of the original image consistent. It is. In this resolution conversion processing, data processing based on a complicated algorithm such as a nearest neighbor interpolation method, a linear interpolation method, a Lagrange interpolation method, and a spline interpolation method is performed.

In the binarization process, how to print minute dots of three primary colors (usually YMC system) in a unit area corresponds to an ink jet printer or an optical color printer in which the printed dots themselves have no gradation. This is a process for deciding whether to express the gradation by dispersing the gradation. As a pseudo gradation expression method using the area gradation, a density pattern method, an error diffusion method, and the like are well known.

[0006]

The conventional digital image processing for reading an original image and enlarging and printing the image is to read the image at a high resolution for the time being, regardless of the enlargement ratio or the printing resolution. Was. For this purpose, large-volume document image data read at a high resolution is converted to high-resolution print data by making full use of the above-described advanced resolution conversion method. Therefore, there is a problem that the time required for data processing becomes long.

Therefore, the present inventor considered changing the idea, setting a certain enlargement ratio and printing resolution as a printing output result, and conversely deriving an appropriate reading resolution therefrom. As a result, it has been found that when the reading resolution of the document is set according to a certain condition in accordance with the printing magnification and the printing resolution, high-quality printing can be performed without performing complicated data processing.

The present invention has been made based on this finding, and it is an object of the present invention to provide a digital image processing method for enlarging and printing a document image with high quality by simple data processing.

[0009]

According to the digital image processing method for reading an original image with a scanner and enlarging and printing the image, the present invention provides a digital image processing method comprising: obtaining a dimension X of an original to be read;
A step of obtaining a size Y of the printing paper to be enlarged and printed; a step of calculating an enlargement ratio Z from a ratio of the document size X to the size of the printing paper Y; and a step of determining the resolution of the printing apparatus to an appropriate value P. Calculating the reading resolution S = P × Z of the scanner by acquiring the enlargement ratio Z and the printing resolution P, and reading the image of the document of the dimension X by the scanner with the reading resolution set to approximately S = P × Z. Temporarily storing the digital image data in a memory, and printing the digital image data stored in the memory on a printing sheet of dimension Y by a printing apparatus having a printing resolution set to substantially P. . More preferably, the print resolution P is set to about 72 d
pi.

[0010]

FIG. 1 shows the configuration of an embodiment of an image processing system to which a digital image processing method according to the present invention is applied. A scanner 2 and a color printer 3 are connected to a normal personal computer 1 as peripheral image processing devices. The image data processing program set up in the personal computer 1 generates various data for controlling the peripheral image processing apparatus based on the digital image processing algorithm of the present invention.

The scanner 2 has a CCD array of about 600 dpi and scans a document image for each of RGB colors.
This is a flat scanner that reads pixels in 8-bit halftone (24-bit color) for each color. The color printer 3 is a laser beam writing type optical color printer 3 using YMC three primary color toners. The maximum printing resolution is 600 dpi. The “pixel” is a minute display unit including 24-bit color data.
A “dot” is a minimum unit that can be printed by a printer, and is a single color “dot”. Therefore, one pixel is represented by a plurality of “dots”. Next, regarding the digital image processing method of the present invention using this system,
A description will be given while showing a specific user interface environment.

First, the dimensions of a document image are obtained. For this purpose, a document is set on a scanner and a reading area is designated. In the present embodiment, the entire area of the original paper is preview-displayed on the display of the personal computer 1, and the mouse pointer is moved while being dragged to designate a rectangular area as the original. Here, it is assumed that an area of 1 inch square is specified. With this operation, the vertical and horizontal sizes and areas are obtained as the original dimensions.

Next, in order to obtain the size of the printing paper to be enlarged, the printing paper is designated. Here, a paper size to be used such as “A4” and the vertical and horizontal dimensions of the print area are input. In this embodiment, when one of the vertical and horizontal dimensions is input, the other size is automatically calculated according to the aspect ratio of the document. According to this input operation, the dimensions of the printing paper are obtained. Here, the printing paper is not a paper size such as “A4” but a printing area when an original is enlarged and printed. If the lateral dimension of this printing paper (area) is, for example, 5 inches,
The vertical dimension is 5 inches according to the aspect ratio (1: 1) of the original image. An enlargement ratio is calculated from the 5 inch × 5 inch print area and the original size of 1 inch × 1 inch to obtain an area ratio of 25 times. Of course, the user interface environment may be such that when a magnification of 25 is input, the vertical and horizontal dimensions of the print area automatically become 5 inches × 5 inches. Next, the print resolution is input. Here, it is assumed that 72 (dot / inch: dpi), which is the lowest resolution that can be set, is specified.

By the above operation and numerical input, the document size X = 1 × 1 = 1 (inch ² ) The printing paper size Y = 5 × 5 = 25 (inch ² ) The enlargement ratio Z = 25 ÷ 1 = 25 (times) ) Print resolution P = 72 × 72 = 5184 (dot / inc)
h ² ) is obtained.

The image processing program calculates these values based on the relational expression of reading resolution S = P × Z. Therefore, S = 5184 × 25 = 129600
(Dot / inch ² ). Since the normal resolution expression is dpi, the square root of 129600 is taken to be 360 dpi. This is the reading resolution. The image processing program controls the scanner and the printer according to these setting conditions. The outline of the control will be described below.

A document image is read with the reading resolution of the scanner set to 360 dpi. The read data is 360x
It becomes digital image data of 360 × 24 (bits) = 388.8 (KB). The PC uses this data as a video
Bitmap development is performed on the AM and displayed on the display.

Next, this bitmap data is stored in the 72d
The image data is converted into print data that is magnified 5 times each in the vertical and horizontal directions of pi. One dot of the printer is the reciprocal of the maximum printing resolution and is 1/600
It is a minute dot with a width of inches. Therefore, one large enlarged dot is formed by arranging 8.333... Fine dots in the horizontal (vertical) direction. However, since fine dots cannot be further divided, eight fine dots are assigned as one enlarged dot so that the enlarged dot is an integral multiple of the fine dot, and the actual print resolution is set to 75 dpi. Processing such as allocating eight minute dots in the line direction and allocating nine minute dots to a certain enlarged dot is performed so as to match the number of pixels in the horizontal (vertical) direction. In this way, the resolution conversion process is appropriately performed,
The printout is performed at a resolution substantially close to the resolution P. Further, the above-described image processing program expresses the color of each pixel in the document image by appropriately binarizing the enlarged dot.

The above-described digital image data processing system is not limited to the above-described embodiment, but may be a device in which a scanner, a control unit (corresponding to the personal computer in the embodiment), and a printer are all or partly integrated. You may. The path from the image data processing unit such as a personal computer to the printer may be performed via a communication line. That is, the data converted into the print data may be transferred to another personal computer or the like via a network represented by the Internet, and the document image may be enlarged and printed by a printer connected to the personal computer.

Further, an important requirement of the digital image processing method according to the present invention is that the dimension X of the document and the reading resolution S and the enlargement ratio Z and the printing resolution P by the printer are represented by the above relational expression, S = P × Z = P × Y / X is to be satisfied. Therefore, for example, image data having a certain number of pixels N such as image data of a document photographed by a digital camera may be used. In this case, since X × S = N, N = P ×
Y, and printing may be performed under the condition of print resolution P = N / Y or print paper size Y = N / P.

[0020]

According to the present invention, an original can be enlarged and printed with high image quality without requiring a complicated resolution conversion process. Further, the print output at the maximum print resolution is not required, and the data amount can be greatly reduced. Therefore, the time required for data processing and the transfer time can be significantly reduced.

Further, by transferring only print data or print conditions, high-quality, large-area image data can be distributed via a network. Moreover, if the printing resolution is about 72 dpi, higher-speed transfer and printing can be performed without deteriorating the image quality.

[Brief description of the drawings]

FIG. 1 shows an example of a system centered on a personal computer as an embodiment of an image data processing system for enlarging and printing a document by a digital image data processing method of the present invention.

[Explanation of symbols]

 1 PC 2 Scanner 3 Color printer

Claims (2)

(57) [Claims] 1. A digital image processing method for reading a document image with a scanner and enlarging and printing the same, wherein a step of acquiring a dimension X of a document to be read and a step of acquiring a dimension Y of a printing paper to be enlarged and printed Calculating the enlargement ratio Z from the ratio of the document size X to the printing paper size Y; determining the resolution of the printing apparatus to an appropriate value P;
And the printing resolution P, and the reading resolution S =
The process of calculating P × Z and the reading resolution is substantially S = P × Z
Reading the image of the document of the dimension X by the scanner set to, and temporarily storing the digital image data in the memory; and storing the digital image data in the memory on the printing paper of the dimension Y by the printing apparatus having the printing resolution set to substantially P. Printing digital image data. 2. A digital image processing method according to claim 1, wherein said print resolution P is a resolution corresponding to approximately 72 dpi.