CZ296032B6 - Display unit - Google Patents

Abstract

The present invention relates to a display unit having a display with a surface formed by display elements wherein the display unit is performed so that each display element is formed by two picture elements (10, 20) with reproducing lights having chromaticity lying in spectrum of saturated chromaticities of CIEix,y color diagram, wherein the saturation and hue difference between the reproducing light chromaticities of these picture elements (10. 20) and chromaticity with 100% saturation lying on the curve of spectral chromaticities of the CIEix,y color diagram is less than color differential resolution capability of human vision. The reproducing light of at least one of these picture elements (10, 20) has chromaticity that can be adjusted within the light wavelength spectrum

Description

(57)

An image display unit having a surface formed by image elements is formed such that each image element is formed by two pixels (10, 20) with reproductive lights having chromaticity lying in the saturated chromaticity area of the CIE _{X v} color chart, where the saturation difference and the chromaticity tone of the reproduction lights of these pixels (10.20) from the chromaticity with 100% saturation lying on the spectral chromaticity curve of the CIE _XV color diagram is less than the color differential resolution of human vision. The reproduction light of at least one of the two pixels (10, 20) has a chromaticity tunable in the wavelength region of the light.

20 May

Display

Technical field

The present invention relates to an image reproduction unit in the field of multimedia technology and other fields of applied image technology.

BACKGROUND OF THE INVENTION

All colorimetric standards of imaging units are still trichromatic. This means that, similarly to the trichromatic scene recording - the decomposition of the scene into three different color paths, still exclusively red - R, green - G and blue - B, additive image reproduction is based on the synthesis of three basic color lights, R, G, B. The present display units have two basic disadvantages from a colorimetric point of view.

The first is the RGB colorimetric system. A disadvantage of colorimetric systems or RGB color spaces is their dependence on a given type of device. For example, the RGB _PAL sensing system on _PAL television cameras acquires different red, green, and blue component values of the scene than the RGB _NT sc sensing system on NTSC television cameras. Also, images and video sequences not produced by natural scene capture but synthetically, for example in a particular computer graphic environment, are stored in different RGB systems or spaces. This makes it impossible to take full advantage of the colorimetric features of all current displays, as well as printing techniques, for example. During reproduction, irreparable color distortions occur.

The second drawback of all current display types is the ability to reproduce only a maximum of about 60% of all colors in terms of the CIE _xy 1931 2-D color chart. This is partly due to the choice of the RGB colorimetric system when creating images by sensing or synthetically, but above all by the physical principle of visualizing these images. The area of reproducible colors determines in the CIE _xy chromaticity diagram a triangle whose peaks correspond to the chromaticities of the three primary lights used in a given reproduction device display. The triangle is inscribed in an area describing all the existing chromaticities, and the area of the triangle is significantly smaller than the area of that area. It is therefore clear that only the color lights whose chromaticity falls within the triangle can be faithfully reproduced in the tone and saturation. Lights with chromaticity outside the triangle reduce their saturation during reproduction. This saturation is limited by the corresponding points on the perimeter of the triangle.

In order to extend the reproducible chromaticity area, the so-called color gamut, of a certain display, it is therefore necessary to make two changes in colorimetric terms. Firstly, to acquire images, whether by television camera capture or synthetically in a graphical environment, in a color space independent of the type of device, for example in the XYZ colorimetric system, as proposed by patent no. 288456. in order to reproduce as far as possible all the existing chromaticities, i.e. in the sense of the CIE _xy color chart, to cover the entire area of the chart with reproductive lights.

It should be noted that it is only by incorporating both requirements that color reproduction can be achieved. It is an object of the present invention to provide a novel method for visualizing color images by a display unit.

-1 CZ 296032 B6

SUMMARY OF THE INVENTION

The above-mentioned disadvantages are overcome by a display unit with an image display whose surface is formed by the image elements. The essence of the new solution is that each pixel is made up of two pixels with reproduction lights having chromaticity lying in the saturated chromaticity area of the CIE _xy color chart, where the saturation difference and chromaticity tone of these pixel reproduction lights from 100% saturation lying on the spectral curve the chromaticity of the CIE _xy color chart is less than the color differential resolution of human vision, wherein the reproductive light of at least one of the two pixels of each pixel has a chromaticity tunable in the wavelength range of light.

In a preferred embodiment, the reproduction light of one pixel of each pixel has a constant chromaticity lying within the saturated chromaticity region of the CIE _xy color chart, where the saturation and chromaticity difference of that pixel reproduction light from 100% saturation with 780 nm wavelength is less than color differential resolution of human eyesight. The reproduction light of the second pixel of each pixel has a chromaticity tunable in the wavelength range of 420 to 550 nm, and the saturation and tone difference of this tunable chromaticity from that of 100% saturation is again less than the color differential resolution of human vision.

The pixels may advantageously consist, for example, of organic LEDs or lasers.

An advantage of said solution is that the range of reproducible colored lights covers the entire range of real existing colored lights.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in more detail with reference to the accompanying drawings in which: Figure 1 schematically illustrates the function of a display unit, the image elements of which are formed by two pixels, one each having reproducing light with chromaticity tunable in the wavelength range; with constant chromaticity. In Fig. 2, the function of the same display unit is schematically indicated, except that both pixels have reproducing lights with chromaticity tunable in the wavelength range. Giant. Fig. 3 shows a CIE _xy color diagram showing the positions of the reproduction lights for the display unit with the function of Fig. 1 and analogously Fig. 4 shows exemplary positions of the reproduction lights for the display unit with the function of Fig. 2. the most economical case of the position of the reproduction lights for the reproduced light of Fig. 4.

DETAILED DESCRIPTION OF THE INVENTION

The extension of the reproducible chromaticity range, i.e. the color gamut, of the image display unit of the present invention is based on the finding that only two leveling lights are sufficient for colorimetric alignment of any light. Because the CIE _xy color chart circuit is a continuous set, there are two possible configurations of the two spectral, i.e. 100% saturated, reproduction lights used for the display of the display unit. Accordingly, the display surface of the display unit is formed by image elements, each of which is made up of two pixels, but certain specific conditions must be met. In both cases, this specific condition is that the reproduction lights of these pixels have chromaticity lying in the saturated chromaticity range of the CIE _xy color chart, preferably on the spectral chromaticity curve of the CIE _xy color chart, where the saturation is 100%. The pixel reproduction lights may also be close to the curve

The spectral chromaticity of the CIE _{x> y} color diagram is in an area where the saturation and chromaticity tone of the reproduction lights of these pixels from the chromaticity at 100% saturation is less than the differential resolution of human vision. In other words, it is an area in the spectral chromaticity curve of the CIE _xy color chart, where the saturation and chromaticity tone of the reproductive light of a pixel is still perceived by the human eye in the same way. In order to achieve coverage of all colors of the CIE _xy diagram, it is necessary that the reproductive light of at least one pixel of each pixel has chromaticity tunable in the wavelength range of light.

In the first case, the display unit is realized such that the reproduction light of one pixel of each pixel has a constant chromaticity lying in the saturated chromaticity area of the CIE _{X y} color chart, where the saturation difference and chromaticity tone of this pixel reproduction light from 100% saturation is less than the color differential resolution of human vision. The second pixel reproduction light of each pixel has chromaticity lying within the saturated chromaticity range of the CIE _xy color chart, where the saturation and chromaticity tone of this pixel's reproductive light from that of 100% saturation is less than the color differential resolution of human eyesight and this chromaticity is tunable in the light wavelength range.

The preferred position of constant chromaticity reproduction light location is then at the red end of the CIE _xy color chart. That is, the reproduction light belonging to one pixel of each pixel lies in the saturated chromaticity area of the CIE _xy color chart, where the saturation and chromaticity tone of this pixel reproduction light from that of 100% saturation at 780 nm is less than color differential resolution of the human eye. In this case, it is sufficient to retune the chromaticity of the reproductive light belonging to the second pixel of each pixel only in the wavelength range 420 - 550 nm, since above this interval the boundary curve of the color diagram is practically a line and a neglect error of 380-420 nm is irrelevant human color perception. 1 and 3 illustrate this case.

Fig. 1 shows the function of such a display unit with an image display 4. The color information, i.e. the brightness, saturation and tone of each point of the scanned or synthetically generated image together with the control, in television technology, synchronization information about that point form the input data. displays. Color information is coded in a particular color system or space. In TV technology, this is the space of brightness Y and the chrominance of RY and BY. In the case of synthetically produced images, it is mostly the space of the basic colors R, G, B. From these input data, the color coordinates x, y of each point of the image to be reproduced are calculated in the first block 1 of the calculation. The brightness Y of these reproduced pixels of the image is either known from the data entering the display or is calculated from the equations of colorimetric transformation between the respective systems. If the brightness Y and the color coordinates x, y of the resulting reproduction point of the image are known, the color coordinate equation x ₂ , y ₂ , ax ₂ , y ₂ and the third block 3 of the calculation are determined in the second calculation block 2 from the colorimetric alignment equation, the luminance ratios Y _x and Y _{2 of the} two lights required to compensate for this resulting aligned or reproduced light. By knowing the luminance Y _2, and Y ₂ and the color coordinate Xn yi and xj, y ₂ two reproduction lights, then together with the control information indicating the location information points in the image resulting data suitable for driving bichromatic display with at least one range of wavelengths of light tunable reproductive light.

In the case of a display unit having one tunable reproductive light and one constant chromaticity reproduction light, in the colorimetric alignment equation, not only the color coordinates x, y and the brightness Y of the light being equal, that is, reproduced, that is, the reproduction, indicated in FIG. 1, X2, at ₂ , namely the reproduction light with a constant chromaticity of the display unit. All that remains is to determine the color coordinates Xi, Yi

CZ 296032 B6 -3 reproducing light with a chromaticity of the tunable wavelength range of light and luminance portions Y1 and _Y2 both reproduction light.

Fig. 3 is an example where the position of two reproduction lights, one reproduction light with a chromaticity tunable in the wavelength range of light represented by one pixel 10 of each pixel and one reproduction light with a constant chromaticity with color coordinates x ₂ = 0.735 ay ₂ = 0.265 lying in the CIE _xy color chart in a spectral chromaticity curve with a wavelength of 780 nm corresponding to the red color represented by the second pixel 20 of each pixel, defined for nine positions of equalized light.

In the second case, the display unit is realized such that each pixel is formed by two pixels with reproduction lights with a chromaticity tunable in the wavelength range of light and this chromaticity lies within the saturated chromaticity of the CIE _xy color chart, where the saturation and chromaticity difference of these reproduction of 100% saturation chromaticity pixels lying on the spectral chromaticity curve of the CIE _xy color chart is less than the color differential resolution of human vision. The operation of such a display unit is shown schematically in Figure 2, where a block display unit with both tunable reproduction lights is shown. Its arrangement is analogous to that of FIG. 1 except that in the second calculation block 2 the color coordinates of the two tunable reproduction lights are determined according to the minimum optical radiative power criterion, and in the third calculation block the luminance ratios of the two reproduction tunable lights are determined. . It follows from the colorimetric alignment equation that there are a large number of equalizing or reproducing light pairs that colorimetrically equalize the reproduced or reproduced light. The present invention proposes the choice of a pair of reproductive lights wherein the requirement of input optical radiant power is minimal to realize the desired perception by human vision. The color coordinates and luminance ratios of the reproductive lights are determined from the colorimetric alignment equation. Thus, in this case, there are many possible positions of such reproduction lights as shown in Fig. 4 where six tunable chromaticity reproduction positions represented by the first pixel 10 'of each pixel and the second pixel 20 of each pixel are defined for one light-aligned. The advantage of this solution is the possibility of using metamerism of colors, a phenomenon where colors of different spectral composition are perceived as colors with the same chromaticity. This means that from the possible positions of the reproductive lights it is possible to select a position at which there is a minimum requirement for input optical radiation power. The most energy-efficient case of Fig. 4 is shown in Fig. 5, where the minimum input optical radiant power is based on the case where one reproduction light has a wavelength of approximately 445 nm.

The following are two specific examples of assessing luminance Y] and _Y2 and chromaticity, a color coordinate x _b yi x _2, y _2, the two reproduction lights proposed bichromatic display unit of the transmission signals Y, Y, B-Y color television or the signals of basic colored lights R, G, B used eg in computer graphics.

Example 1

A display with one tunable and one non-tunable reproductive light is contemplated.

The color coordinates of the reproduced light x = 0.350, y = 0.200 and the reproduction light brightness Y = 100% were determined from the color television transmission signals, i.e. the brightness Y and the chrominance RY and BY or the basic color lights R, G, and B signals. It is further considered that 100% saturated non-tunable reproductive light has a wavelength of 780 nm, corresponding to chromaticity with color coordinates x ₂ = 0.735, y ₂ = 0.265. The task now is to determine the color coordinates of the tunable reproduction light x _b yi and the luminance ratio of the reproduction lights Yi and Y ₂ .

-4GB 296032 B6

The color coordinate of the tunable reproduction light x _b yi is determined as the intersection of the latitude, starting from the CIE _{x> y} color chart point of the non-tunable reproductive light color and passing through the CIE _xy color chart point of the resulting light to be reproduced, with the spectral chromaticity curve colors CIE _xy . Figure 3 illustrates this situation.

The algorithm for calculating the common point of said line with the spectral chromaticity curve of the CIE _{x> y} color chart may be arbitrary, but it must meet the requirement of a certain maximum intersection time in the system, for example with respect to a continuous sequence of images in the video sequence. At the same time, the error of determining this intersection, ie the difference between the correct and the determined chromaticity of the reproductive light, must be less than the color differential resolution of human vision. For the above case, which corresponds to the lowest half-line in Figure 3, the intersection has color coordinates

Xi = 0.083, yi = 0.157, which corresponds to 100% of the reproductive light system at 482 nm.

From equation colorimetric compensation determined proportions luminance Yi and Y ₂ reproduction light on the brightness Y of the resultant reproduced light.

Thus, the brightness Y _{2 of the} reproduction light with constant chromaticity, in the example at 780 nm, is given by the following calculation:

Y ₂ = Y * (x / y - x i / y _t ) / (x ₂ / y ₂ - X] / yi) = 100 * (0.350 / 0.200 - 0.083 / 0.157) / (0.735 / 0.265 0.083 / 0.157)

Y ₂ = 54.5%

The luminance of reproductive light with tunable chromaticity, in this case 482 nm, is determined by:

Y] = Y - Y ₂ = 100-54.5 = 45.5%

This calculation is performed for each image element of the display.

Example 2

A display with both tunable reproductive lights is contemplated.

The color coordinates of the reproduced light x = 0.300, y = 0.200 and the reproduction light brightness Y = 100% were determined from the color television transmission signals, i.e. the brightness Y and the chrominance RY and BY or the basic color lights R, G and B signals. The task now is to determine the color coordinates x _b y ₁ and x ₂ , y ₂ and the luminance ratios Y 1 and Y _{2 of the} pixel reproduction lights of the respective pixel.

There are a large number of matching or reproducing lights in this case. The solution according to the invention proposes the choice of a pair of reproductive lights where the requirement of the optical input power is minimal to realize the desired perception by human eyes.

The algorithm for calculating the color coordinates of the reproductive lights is not the only one and therefore cannot be prescribed again. By analogy with the previous example, it is possible to look for color coordinate pairs of reproductive lights as common points of lines passing through a point in the CIE _xy color chart of the color coordinates of the resulting light to be reproduced, with a curve

-5GB 296032 B6 spectral chromaticities of the CIE color diagram _{x> y} . The situation is illustrated in FIG. 4, where in the present example the color coordinates of six pairs of intersections are plotted, theoretically being infinite.

Xii = 0.169, yn = 0.007; x ₂ i = 0.499, y ₂ i = 0.500,

X12 = 0.165, _y12 = 0.010; x ₂₂ = 0.506, y ₂₂ = 0.493,

X ₁₃ = 0.158, γ ₁₃ = 0.017; x ₂₃ = 0.519, y ₂₃ = 0.480

Xi4 = 0.146, y = 0.028 _{14; 24} x = 0.539, y = 0.461 ₂₄ x ₁₅ = 0.127, polyphenyl = 0.053; x ₂₅ = 0.569, y ₂₅ = 0.430, x ₁₆ = 0.095, y ₁₆ = 0.122; x ₂₆ = 0.663, y ₂₆ = 0.337.

The luminance ratios to be determined as in the previous case are:

Yn = 2.02%; Y ₂ i = 97.98%,

Y ₁₂ = 3.14%; Y ₂₂ = 96.86%,

Y, ₃ = 5.09%; Y ₂₃ = 94.91%

Y ₁₄ = 8.47%; Y ₂₄ = 91.53%

Y ₁₅ = 16.32%; Y ₂₅ = 83.68%

Y16 = 38.86%; Y ₂₆ = 61.14%.

By converting the luminance as photometric quantities into the radiant optical power P as a radiometric quantity, it is possible to determine such a pair of reproductive lights where the input of the radiant optical power is minimal to realize the desired perception by human vision.

Pi = 73.3%

P ₂ = 61.7%

P ₃ = 61.7%

P ₄ = 63.3%

P ₅ = 73.3%

P ₆ = 100%, where Pi is the sum of the necessary optical powers of the first pair of reproductive lights, P ₂ is the sum of the necessary optical powers of the second pair of reproductive lights, etc.

In this case, a pair of reproductive lights having the color coordinates x _n = 0.158, y _n = 0.017, and x ₂₃ = 0.519, y ₂₃ = 0.480, which corresponds to the wavelengths 449 and 581 nm of the first and second reproductive light, are optimally selected for energy. This case is then illustrated by the curve in Fig. 5.

Industrial applicability

The present invention is applicable in all areas of color image reproduction such as television sets, computer monitors and the like. Especially advantageous is the application of the invention in these fields of human activity where high demands are placed on the visualization of color images in terms of color fidelity of reproduction and an extremely wide range of reproducible colors, for example in medicine or space research.

Claims (4)

PATENT CLAIMS An image display unit having an area of image elements, characterized in that each image element is formed by two pixels (10, 20) with reproductive lights having chromaticity lying in the saturated chromaticity area of the CIE _xy color chart, where the difference the saturation and chromaticity tone of the reproduction lights of these pixels (10, 20) from the chromaticity with 100% saturation lying on the spectral chromaticity curve of the CIE _xy color chart is less than the color differential resolution of human vision, the reproductive light of at least one of the two pixels ( 10, 20) has a chromaticity tunable in the wavelength range of light. Display unit according to claim 1, characterized in that the reproduction light of one pixel (10 ') of each pixel has a constant chromaticity lying in the region of the saturated chromaticity of the CIE _xy color chart, where the saturation and chromaticity difference of that pixel reproduction light (10). 10 ') from chromaticity at 100% saturation with a wavelength of 780 nm is less than the color differential resolution of human vision and the reproduction light of the second pixel (20) of each pixel has a chromaticity tunable in the wavelength range 420-550 nm and saturation difference; The tone of this tunable chromaticity from chromaticity with 100% saturation is again less than the color differential resolution of human vision. Display unit according to claim 1 or 2, characterized in that the pixels (10, 10 ', 20) are formed by organic LEDs. Display unit according to claim 1 or 2, characterized in that the pixels (10, 10 ', 20) are formed by lasers.