JP2006339984A - Video printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a video printer capable of outputting a print of picture quality suitable to respective areas by applying different picture quality adjustments according to characteristics of respective pixels of still picture data. <P>SOLUTION: The video printer is equipped with a decision means of comparing luminances of the respective constituent pixels of the stored still picture data with a previously specified luminance threshold to decide a range to which a luminance of each constituent pixel of the stored pixel data belongs and a picture quality adjusting means of applying picture quality adjustments of contrast and lightness to each the constituent pixels, and thereby outputting a print by implementing the picture quality adjustments according to different image characteristics of respective areas even when the image comprises the plurality of areas having the different characteristics. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a video printer that prints out an image stored as a digital signal, and more particularly to an image quality adjustment function during print output.

Conventional video printers perform uniform image quality adjustment on the entire image data as image quality adjustment means for printing out image data stored as digital data in the video printer, or the user can individually control the image data. A method has been used in which a part of an area is designated by manual operation and image quality adjustment is performed on the designated area (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-11140 (FIGS. 5 and 6)

When printing still image data, instead of performing uniform image quality adjustment on the entire image, it may be desirable to perform different image quality adjustments according to the characteristics of each pixel of the image. An example of such an image There is a medical fundus image. The fundus image includes a particularly bright portion called a nipple and a medium-brightness portion called a peripheral portion at the center of the fundus. This nipple has a narrow gradation range and subtle gradation. If the contrast is increased, color skipping (the gradation change between adjacent pixels may not be smooth) may occur. Is desired. On the other hand, if the contrast is lowered in the peripheral portion, the vividness of red is lost, and image quality adjustment that increases the contrast is desired in order to make the blood vessels clearly visible. Therefore, it is necessary to perform image quality adjustment corresponding to the characteristics of each pixel of still image data, rather than performing one type of image quality adjustment for the entire region of still image data.

However, conventional video printers only perform uniform image quality adjustment on the entire still image data, or perform individual image quality adjustment by manual operation on a part of the still image data. Therefore, there is a problem in that printing cannot be performed by performing different image quality adjustments according to the characteristics of each pixel of still image data at the time of image print output.

The present invention has been made to solve the above-described problems, and performs different image quality adjustments according to the characteristics of each pixel of still image data, and print output with optimum image quality for each region. The purpose is to obtain a video printer capable of the above.

  The video printer according to the present invention uses, for example, the luminance of each pixel as a data value representing the attribute of each constituent pixel of still image data held in the video printer, and each constituent pixel of the accumulated still image data. A determination means is provided for determining which range the luminance of each constituent pixel of the accumulated still image data belongs by comparing the luminance with a predetermined luminance threshold.

According to the present invention, different image quality adjustments can be performed according to the characteristics of each pixel of a still image. Therefore, even when a still image is composed of a plurality of regions having different characteristics, it is suitable for each region. Since the image adjustment can be performed, it is possible to obtain a print output in which the optimum image quality adjustment is performed for the entire image.

Embodiment 1 FIG.
FIG. 1 is a diagram showing the configuration of a video printer according to Embodiment 1 of the present invention. First, storage means for storing a video image signal input from the outside by a video printer as still image data will be described. The video signal processing unit 1 converts an externally input video video signal A (video signal format is, for example, a composite signal) into an RGB three-system analog video signal B. The A / D conversion unit 2 samples and quantizes the analog video signal B, so that 1-byte digital still image data per pixel of each RGB system (the value of this data is 0 to 255, 0 Is the darkest and 255 is the brightest), and is output as still image data C. The memory control unit 3 stores the still image data C in the memory 4 by performing control to write the still image data C into the memory 4.

In the memory 4, it is assumed that the stored image is composed of m pixels in the horizontal direction and n lines in the vertical direction. Accordingly, the memory 4 includes 1 byte of luminance data for each color component of RGB for each pixel, and m * n bytes of data are stored in the memory 4 for each color component for the entire image. . Here, if the coordinates in the image space of the image stored in the memory 4 are (x, y) (where 1 ≦ x ≦ m, 1 ≦ y ≦ n), R, G at the coordinates (x, y) , B is described as luminance data Rxy, Gxy, Bxy.

Next, when the image of the still image data stored in the memory 4 is printed out, the memory control unit 3 displays the still image data stored in the memory 4 in a unit of data for one line of the image. Readout control is performed as image data D, and output to the transfer unit 5. The transfer unit 5 performs image quality adjustment for each pixel included in still image data for one line of the still image data D. Thereafter, after the color format of the image data is converted from RGB to YMC (yellow, magenta, cyan), it is converted to a time length pulse E for turning on the thermal head and output to the thermal head 6.

FIG. 2 is a flowchart showing a processing procedure of image quality adjustment of the transfer unit 5 according to the first embodiment. Next, image quality adjustment processing in the transfer unit 5 will be described with reference to the processing flow of FIG. The memory 4 contains still image data of each color component of RGB for each pixel. However, since the processing for each color component in the transfer unit 5 is performed in the same procedure, the R component is described in the following description. Only the process will be described.

First, the transfer unit 5 extracts the luminance data Rxy of the R component of the pixel corresponding to the image space coordinates (x, y) from the still image data for one line read from the memory 4 (Step 1). Next, by comparing Rxy with a preset luminance threshold z, it is determined whether the luminance data Rxy belongs to Rxy ≧ z or Rxy <z (step 2). That is, step 2 is a determination unit that determines whether the luminance that is an attribute of each constituent pixel belongs to a predetermined range, and outputs a determination result. A pixel corresponding to Rxy ≧ z has a certain brightness or higher. This means that a pixel corresponding to Rxy <z is included in an area less than a certain brightness. Note that the threshold value z is set in the transfer unit 5 in advance. This threshold value z can be changed. By changing the threshold value z, the target area for each image quality adjustment in still image data can be changed.

If the determination result is Rxy ≧ z, image quality adjustment by the image quality adjustment function g is performed on this pixel data (step 3a). On the other hand, when the determination result is Rxy <z, image quality adjustment is performed on the pixel data by the image quality adjustment function f (step 3b). That is, step 3a and step 3b constitute image quality adjusting means for adjusting the image quality of each pixel. The image quality adjustment function is a function for obtaining brightness data R′xy after image quality adjustment from brightness data Rxy before image quality adjustment, and specifically, R′xy = f (Rxy) = a * Rxy + b and R′xy = g (Rxy) = c * Rxy + d (where a, b, c, and d are constants).

FIG. 3 shows the concept of image quality adjustment. FIG. 3A is a diagram showing the R color component Rxy of the luminance data for each pixel of still image data before image quality adjustment. The region A in which the entire still image data is Rxy ≧ z and Rxy <z. It shows that it is composed of two areas of a certain area B. When the image quality adjustment process in the transfer unit 5 described above is performed on the still image data, the image quality adjustment function g is applied to the R color component Rxy of the pixels included in the region A, and the pixels included in the region B are detected. As a result of applying the image quality adjustment function f to the R color component Rxy, as shown in FIG. 3B, the R color component R′xy of the luminance data for each pixel in the region A is R′xy = g. The image quality is adjusted to (Rxy), and the R color component R′xy of the luminance data for each pixel in the region B indicates that the image quality is adjusted to R′xy = f (Rxy).

The image quality adjustment function can realize various image quality adjustments by setting constants in the function. Specifically, the contrast can be adjusted by the constant a in the image quality adjustment function f, and the brightness can be adjusted by the constant b. A method for adjusting contrast and brightness will be described with reference to the drawings. FIG. 4 plots the image quality adjustment function f when the constant b is changed with the constant b = 0, with the horizontal axis representing luminance data Rxy before image quality adjustment and the vertical axis representing luminance data f (Rxy). As shown in FIG. 4, when a = 1, it corresponds to a case where no substantial image quality adjustment is performed. When a> 1, the contrast is increased. When a <1, the contrast is decreased. Each corresponds. FIG. 5 plots the image quality adjustment function f when the constant a is constant and the constant b is changed, with the horizontal axis representing luminance data Rxy before image quality adjustment and the vertical axis representing luminance data f (Rxy). It is. As shown in FIG. 5, when b> 0, it corresponds to an adjustment that increases the overall brightness, and when b <0, it corresponds to an adjustment that decreases the overall brightness. In the image quality adjustment function g, the constants c and d have the same effects as the constants a and b, respectively.

Although the image quality adjustment function for the R component has been described above, the image quality adjustment for the G component and the B component can be similarly performed using the image quality adjustment function. That is, G′xy = f ₂ (Gxy) = a ₂ * Gxy + b ₂ and G′xy = g ₂ (Gxy) = c ₂ * Gxy + d ₂ are used as the image quality adjustment function for the G component, and for the B component B′xy = f ₃ (Bxy) = a ₃ * Bxy + b ₃ , and B′xy = g ₃ (Bxy) = c ₃ * Gxy + d ₃ may be used as the image quality adjustment function. Here, if each constant of the image quality adjustment function has a relationship of a = a ₂ = a _3, b = b ₂ = b ₃ , c = c ₂ = c _3, and d = d ₂ = d ₃ , the image quality adjustment is performed. If the image quality adjustment is performed while maintaining the previous hue, and each constant of the image quality adjustment function does not satisfy the above-described relationship, the image quality adjustment is performed to a different hue.

After performing the processing in step 2 and step 3 for all the pixels included in one line of image data, the luminance data R′xy after image quality adjustment is color-converted from RGB format to YMC (step 4), and thermal It is converted into a long time pulse F for turning on the head (step 5) and transferred to the thermal head (step 6).

As described above, since the video printer according to the first embodiment enables different image quality adjustment for each pixel based on the luminance that is the attribute value of each pixel of the image, a plurality of images having different characteristics. Even in the case where the image data is composed of these areas, it is possible to perform print output by adjusting the image quality according to the image characteristics of each area.

For example, in the case of the medical fundus image described above, the thin capillaries in the nipple are usually very difficult to distinguish, and when the contrast is increased, the gradation changes suddenly, causing color skipping and making it invisible. Therefore, by adjusting the image quality to reduce the contrast, it is possible to moderate the gradation change at the nipple and to eliminate the lack of information necessary for diagnosis. On the other hand, by adjusting the image quality to increase the contrast in the peripheral area, relatively thick blood vessels running in the peripheral area can be clearly displayed.

Although the image quality adjustment function for the R component has been described in the first embodiment, the image quality adjustment for the G component and the B component can be similarly performed using the image quality adjustment function. That is, G′xy = f ₂ (Gxy) = a ₂ * Gxy + b ₂ and G′xy = g ₂ (Gxy) = c ₂ * Gxy + d ₂ are used as the image quality adjustment function for the G component, and for the B component B′xy = f ₃ (Bxy) = a ₃ * Bxy + b ₃ , and B′xy = g ₃ (Bxy) = c ₃ * Gxy + d ₃ may be used as the image quality adjustment function. Here, if each constant of the image quality adjustment function has a relationship of a = a ₂ = a _3, b = b ₂ = b ₃ , c = c ₂ = c _3, and d = d ₂ = d ₃ , the image quality adjustment is performed. If the image quality adjustment is performed while maintaining the previous hue, and each constant of the image quality adjustment function does not satisfy the above-described relationship, the image quality adjustment is performed to a different hue.

In the first embodiment, the image quality adjustment functions f and g are linear functions of the luminance Rxy. However, the image quality adjustment functions f and g are not limited to this, and are more complicated by using a higher-order function of the luminance Rxy as the image quality adjustment function. Image quality adjustment can also be performed.

Embodiment 2. FIG.
FIG. 6 is a flowchart showing the image quality adjustment processing operation in the transfer unit 5 in the video printer according to the second embodiment of the present invention. In the first embodiment, the determination unit (step 2) in the transfer unit 5 uses one threshold value z as the luminance threshold value. However, a plurality of threshold values, for example, z1, z2,. Thus, determination using n threshold values (however, z1 <z2 <... <Zn) can also be performed. Then, by preparing (n + 1) image quality adjustment functions, f1, f2,..., Fn + 1 as image quality adjustment means corresponding to the determination result, finer image quality adjustment is performed on the entire image. be able to.

Since the difference between the second embodiment and the first embodiment is only the configuration of the transfer unit 5, the image quality adjustment process flow of the transfer unit 5 will be described below with reference to FIG. In FIG. 6, step 1 and steps 4 to 6 are the same as the processing flow shown in FIG.

The determination means in Step 2 uses the two threshold values z1 and z2 as threshold values, and compares the luminance data Rxy of the R component of the pixel with the values of z1 and z2. Accordingly, it is determined whether Rxy belongs to any range of Rxy <z1, z1 ≦ Rxy <z2, and z2 ≦ Rxy.

Next, image quality adjustment is performed using an image quality adjustment function corresponding to the determination result in step 2. Specifically, when Rxy <z1, the image quality adjustment function f1 (step 3a), when z1 ≦ Rxy <z2, the image quality adjustment function f2 (step 3b), and when z2 ≦ Rxy, the image quality adjustment function f3 (step The image quality adjustment is performed using 3c). The entire steps 3a, 3b, 3c constitute the image quality adjusting means.

As described above, since the video printer according to the second embodiment includes the determination unit using a plurality of threshold values and the image quality adjustment unit using a plurality of image quality adjustment functions, the image has different characteristics. In the case of a plurality of areas, a print output with finer image quality adjustment can be obtained.

In the first and second embodiments, the luminance of the pixel is used as the independent variable of the image quality adjustment function. However, the image quality adjustment function using other attributes such as hue, saturation, and brightness as independent variables. Can also be used. For example, when the saturation is an independent variable, in the process of step 2 of the operation flow (FIG. 2) of the transfer unit 5 in the first embodiment, first, the saturation s is obtained from the RGB component of the pixel, and this saturation is obtained. It is only necessary to compare s with a preset saturation threshold Sz.

It is a block diagram of the video printer of Embodiment 1 of this invention. 3 is a processing flow of a transfer unit in the video printer according to the first embodiment of the present invention. It is a figure which shows the concept of the image quality adjustment function of Embodiment 1 of this invention. It is explanatory drawing of the contrast adjustment of Embodiment 1 of this invention. It is explanatory drawing of the brightness adjustment of Embodiment 1 of this invention. It is the processing flow of the transfer part in the video printer of Embodiment 2 of this invention.

Explanation of symbols

1 ... Video signal processing unit 2 ... A / D conversion unit 3 ... Memory control unit 4 ... Memory 5 ... Transfer unit 6 ... Thermal head

Claims (3)

Accumulating means for accumulating the input video signal as still image data, and determining whether a data value representing an attribute of each constituent pixel of the accumulated still image data belongs to a predetermined range and outputting a determination result A video printer comprising: determination means for performing image quality adjustment; and image quality adjustment means for performing different image quality adjustment for each of the constituent pixels based on the determination result. The determination unit makes a determination based on luminance data that is a data value representing an attribute of a constituent pixel of still image data, and the image quality adjustment unit adjusts contrast by multiplying the luminance data of the constituent pixel by a specific constant, and the configuration 2. The video printer according to claim 1, wherein the brightness is adjusted by adding or subtracting a specific constant to the luminance data of the pixels. 3. The video printer according to claim 2, wherein the range of the data value representing the attribute of the constituent pixel in the judging means is designated based on a plurality of threshold values of the luminance data.

Images