JPS59123390A - Video printer - Google Patents

Abstract

PURPOSE:To obtain an easy-to-see picture with a less quantized level by using >=2 kinds of lookup tables depending on the characteristic of an object picture so as to obtain a chrominance signal. CONSTITUTION:A video signal 1 from a color television is applied to a characteristic extracting section 2 and a switch mechanism 3. The characteristic extracting section 2 controls the switch mechanism 3 depending on the characteristic of the video signal 1 and the video signal 1 is applied to any of plural lookup tables 4. Further, a print mechanism 5 prints out a color picture by an output of the table 4. Thus, even if the number of quantized levels of the chrominance signal is decreased, since the lookup table 4 is changed depending on the characteristic of the picture signal 1, the easy-to-see picture is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to signal processing means in a video printer for obtaining full-color hard copies of color television video signals.

In recent years, video decks have become widespread, and video discs have appeared, making it easier to obtain still image signals from color television. A magnetic recording camera was also announced, which was designed to be used in the same way as traditional iron salt photography, and also outputs color television still image signals.

As described above, as it becomes possible to obtain high-quality color still images, the demand for obtaining the still images as hard copies increases. Conventionally, instant photography has been used to meet this demand.

The method using instant photography has high running costs, and it is not easy for general users to accurately install the camera on the front of the television set, which can be said to be a troublesome task.

Furthermore, a video printer that combines a dedicated flat CRT and an instant photo has little graphic distortion and good light balance, but it is currently too expensive for general household use and is limited to special uses.

However, recently, the development of printing principles capable of color printing, such as inkjet, thermal transfer, and electrical transfer, has progressed, and an environment has become available that can meet the above-mentioned T1 color requirements.

By the way, in each of the above printing principles, when performing full color printing, cyan and magenta are printed.

Three types of yellow coloring materials and even a gray plate are used, but in order to determine the printing amount of each coloring material from the Y-Q signal or RGB Tsukuda-Q, which is the video signal of color television, various types of coloring materials are used. Signal processing is required. First, if the video signal is a Y/Q signal, it must be converted into an RGB signal, and then the gamma-corrected signal for the cathode ray tube must be inversely corrected.

Furthermore, since the spectral characteristics of the cyan, magenta, and yellow hues used are not ideal, it is necessary to balance each coloring material in the masking matrix. When using a black plate, neutral color components are calculated, and if necessary, undercolor removal processing is performed for the three hues.

Furthermore, it is necessary to correct the characteristic of the modulation degree of the input signal versus the image density, which is determined by the printing principle.

The above signal processing has conventionally been performed using hardware such as a gamma correction circuit or a matrix circuit. However, hardware processing is inconvenient for immediately responding to changes in color materials, printing methods, and even changes in target images.

Furthermore, if software processing using a CPU were to be executed for all 260,000 pixels, it would take more than an hour, making it extremely impractical.
A lookup table is used to determine the amount of printing for cyan, magenta, yellow, processed and black plates. Lookup tables are used in some large-scale image processing devices.

Figure 1 shows the concept of a lookup table.

The three video signals of color television are digitized to create a three-dimensional address space R, G, and B, with one address assigned to every combination of signal strengths r, g, and b. ing. Each address contains C, M, Y, and BK as a result of the signal processing for the signal strength.
I have already memorized A'), rFJ, and cyan, magenta, and yellow.

In addition, when printing a black plate, t can be extended by N)'ε.

When using the above lookup table, the amount of memory that must be used is determined depending on how many bits the signal is handled with. Considering engraving seal printing using a black plate, 4 bits is about 8.2 kilobytes.

5 bits requires approximately 82 kilobytes of memory, and 6 bits requires approximately 786 kilobytes of memory. Considering the current price of computer equipment, general consumer equipment has no choice but to perform 4-bit processing, or at most 5-bit processing. 4 bits means 16 for each color.
It can only represent image density in stages, and even with 5 bits, each color has a 32-level weighting. Normally, it is said that it is necessary to use a correction level of 100 or more to obtain a satisfactory reproduced image for any image.
As mentioned above, it is difficult to reproduce images at a low prediction level to cope with images of the highest quality. For this purpose, several types of lookup tables are prepared and n! A video printer has been proposed in which a user of a video link can arbitrarily select a printer based on the characteristics of an image, but there has been a demand for automatic selection of a look-up table.

The present invention responds to such demands by providing a video printer capable of automatically selecting a look-up table, and will be described in detail below.

FIG. 2 is a conceptual diagram of the configuration of a video printer according to the present invention.l is a video signal from a color television, 2 is a feature extraction unit for a symmetrical image, The output of switch 3 (controls the toy). 4 is a plurality of lookup tables, and only the one selected by switch mechanism 3 is activated. 5id at least cyan, magenta, yellow This is a mechanism for performing full-color printing using three types of coloring materials. 6 shows the entire video printer according to the present invention.

Of the above configurations, the symmetric image feature extraction section 2 determines from the video signal what kind of properties the image has and which built-in lookup table should be used to obtain the most preferable hard copy. It has the function of determining whether or not the purple color is present and controlling the switch equipment q3.

The features of the symmetrical image in question include brightness, contrast color saturation, hue, and even spatial frequency spectrum, but the feature extraction unit 2 extracts multiple items of these features. Alternatively, determine the optimal lookup table for one item.

This will be explained below using recommended examples.

As video signal 1 of a color television, a signal obtained by quantizing an RGB signal to 4 bits using an Aρ converter was used. Three lookup tables 4 are used, each forming an address space for 4096 addresses,
This is a ROM that stores four-phase data (cyan, magenta, yellow, and black) at each address, 4 bits each, 16 bits in total.The total storage capacity of the lookup table is approximately 25 kilobytes. The data stored in the up-table includes inverse correction of gamma correction for cathode ray tubes, correction of color distortion caused by imperfect spectral characteristics of each color material using a masking matrix, and printing amount of black plate from neutral color components. This is the result of determining and removing the undercolor of each color material, and correcting the image sharpness characteristics with respect to the modulation degree of the input signal.The three lookup tables are : Output faithful data.

B: Output darker data.

C: Output brighter data.

Mr., data processing. The symmetric image percentage extraction unit 2 compares the value of the average signal component of the entire screen with a preset threshold value and instructs the switch machine 3 which lookup table to select. The selected lookup table converts the R()B data into hue and black printing amount data, which is sent to a full-color printing machine such as the inkjet method described in Section 5, which calculates the printing amount of each ink. control.

By using the video printer with the above configuration, images with dark tones can be produced by using the lookup table C, and images with high tones can be produced by using lookup table B. By using look-up table A, a well-organized image could be easily obtained without disturbing the color balance.

In addition to the above examples, full color printing t'-:'t
Even in the example in which thermal transfer was used as a5, an image that was always easy to see was able to be obtained by automatic selection of the look-up table.

As described above, according to the present invention, it has been possible to realize a 1L video printer that can automatically obtain an easily viewable image without disturbing the color balance even when using a small quantization level.

[Brief explanation of drawings]

FIG. 1 shows the concept of a lookup table in the present invention. FIG. 2 shows 17. of the video printer according to the present invention. y formation is shown conceptually. 2: Television video signal 2: Symmetrical image feature extraction unit 3: Switch machine 4: Image capture table 5: Full-color print viewing using at least three types of color materials: cyan, magenta, and yellow. 6: Overall video printer according to the invention. Above G signal Figure 2 R I wording procedural amendment (voluntary) Yofi+ 58112□9,1 Commissioner of the Japan Patent Office 1 Indication of the case Patent Application No. 234450 of 1983 2 Invention 3rd name video printer 3 , Person making the amendment 5 Written amendment for the procedure for increasing the number of inventions due to sleeve correction (voluntary) 1 Amend the scope of the claims as shown in the attached sheet and attach it. 2. Specification, line 1 from the bottom of the 200th page - The phrase ``There is little distortion in the figure,'' is corrected by ``There is little distortion in the figure 1.'' 3 Mei IiH book 5th line 2nd line says, "You can read out the imprint of the horse y tan with the song Qi." . 111 [Line 611, page 7, 2nd line, 1st line from the bottom of page 889] I am attaching the engraved version of the surface of the furnace 2j, 1, as shown in the attached sheet, with a one-size-fits-all correction. Claims (1) A video printer that uses at least three types of coloring materials, magenta, and yellow, to obtain a hard copy of a color te1/vision image, in which a color television video signal is digitized. In one-to-one correspondence with the signals,
There are two or more types of look-up daples for printing three types of color materials: cod soane, magenta, and yellow.1
7. A video printer characterized by extracting 41+' features of the target image to determine the lookup Dave/L to be used. (2) Color television video signal area, black version A video characterized in that it uses two or more types of look-up tables for determining the image of the image, and has a 1" length of the target image for determining the look-up table to be used. printer.

Claims (1)

[Claims] (11) Color television using at least three hues of cyan, magenta, and yellow.
- A look-up table for determining the printing amount of the three colors cyan, magenta, and yellow in one-to-one correspondence with the digital edition of the color television video signal in the video printer that obtains the digital copy. Cure three or more types of symmetrical images and decide which lookup table to use! A video printer characterized by having a 19-character feature extraction section. (2) It has three or more types of look-up tables for determining the color television video signal and the printing amount of the black plate, and it has a symmetric image feature extraction unit for determining the look-up table to be used. A video printer characterized by: