JPS60140381A - Method and apparatus for automatically correcting electro-optic conversion characteristic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of the Invention The present invention relates to an image correction method and apparatus for a display device such as a CRT display device.

1. Prior Art - CRT display devices are used for a wide variety of purposes related to image display. These include, for example, an imager in a television, an output device for computer graphics, an output device for a medical image processing device, and the like.

Furthermore, the images displayed on a CRT display are broadly divided into two types: color and black and white, and depending on the purpose of use, switching between positive and negative images may be required.

Furthermore, the displayed image may be required to be recorded on film in addition to being visually observed by a person.

Among these various uses, when displaying still images, it is often necessary to maintain the brightness and chromaticity of the displayed screen within an allowable error range. This is a particularly important requirement when the displayed image is to be recorded on film or used for measurements related to visual function.

When a CRT is used as an image display device, uneven brightness occurs with respect to the coordinate position of one display screen, which is known as shading. Also,
In the case of color image display, a phenomenon is likely to occur in which the path of the electron flow when passing through the shadow mask varies depending on the coordinate position on the 687 screen. When recording an image displayed on a CRT onto a film, it is necessary to compensate for gamma characteristics in consideration of the photosensitive characteristics of the film. This correction is particularly important when switching between displaying positive and negative images from the same data and recording them on film.

In addition to these problems, in CRT display devices, conversion characteristics between input voltage and brightness (light-light conversion characteristics)
It is unavoidable that long-term fluctuations due to aging and short-term fluctuations due to fluctuations in ambient temperature and power supply voltage will occur.

1. OBJECTS OF THE INVENTION 1. An object of the present invention is to provide a correction method and apparatus that solve the above-mentioned problems in CRT display devices.

1. Structure of the present invention 1. The present invention causes a display/f device to switch and display a calibration display image for each screen coordinate, detects a change in brightness of the calibration display image for each screen coordinate, and uses this detected value to display a calibration display image for each screen coordinate. The present invention is characterized in that spatial variations in the brightness or density of the display screen are corrected by performing feedback correction on the brightness signal in the display screen.

The present invention also provides a display image memory, a display device that displays data stored in the display image memory, and a brightness measuring device that measures the brightness of the image displayed on the display device in a color and monochrome image display system. ,
A storage device for recording output signals of the luminance measuring device, operation control of the display image memory and the storage device, control of signal transfer between the display image memory and the storage device, and correction control of the signal transfer. This micro-prosensor calibrates the electro-optic conversion characteristics of the display device from the measured luminance value, and when displaying an actual image, the data of the image to be displayed is calibrated once. It is characterized in that correction is performed based on the electro-optical conversion characteristics.

−Implementation example− Embodiments of the invention will now be described in detail with reference to the drawings.

FIG. 1 shows a block diagram representing an embodiment of the electro-optical conversion characteristic automatic correction system of the present invention. In FIG. 1, reference numeral 1 indicates Yaik A. Brosse...I, which controls image correction in the present invention. In the figure, 2 is a frame Φ memory serving as a display image memory, and 3 is a display device. Furthermore, 4 is a brightness measuring device, and 5 is a storage device.

The micro Φ processor 1 stores a calibration pattern in the frame memory 2. The frame memory 2 is a storage device that stores image data for one screen displayed on the display device 3. An example of a calibration pattern is shown in FIG.

The large rectangle shown in FIG. 2 covers the entire display screen of the display device 3. The calibration pattern has coordinates (X.

It is a spot that is displayed only in a relatively small area centered on y) and has a constant brightness.

The brightness of the displayed spot is measured by a brightness measuring device 4.

The brightness measuring device 4 is a photoelectric converter whose observation field is adjusted so as to cover the entire display surface of the display device 3, and which sends out an output signal related to the average brightness within the observation field.

The output signal of the luminance measuring device 4 is stored in the storage device 5 while being associated with the values of (', x+y> and L given from the micro-prosensor 1.
This measurement is made for several levels of brightness for y).

Furthermore, by performing the same process for other appropriate position coordinates, the electro-optical conversion characteristics of the display surface of the display device 3 are stored in the storage device 5 using the coordinates as parameters. That is, the electro-optical conversion characteristics of the display device 3 are calibrated.

Next, display modes will be explained.

The data of the image to be displayed is stored in the frame memory 2 via the input terminal 76. Next, one pixel stored in the frame memory 2 (the coordinates of this pixel are (x, y
) is sent to the microprocessor 7sl, and the coordinates (x.) are stored in the storage device 5.

It is compared with the electro-optical conversion characteristic corresponding to y).

As a result of the comparison, necessary feedback correction is applied to the data of this pixel so that the correct brightness is displayed at the coordinates (x, y) of the display screen of the display device 3, and the corrected data is returned to the memory during the frame. .

If such correction work is performed sequentially for all pixel data, the frame memory 2 will store data that has been corrected for the influence of variations in the electro-optical conversion characteristics of the display screen of the display device 3. . The image displayed on the display surface of the display device 3 based on this data has correct gradation at least as far as it is viewed from the position where the luminance measuring device 4 is placed. Therefore, in the calibration mode,
By placing a recording camera at the position where the luminance measuring device 4 was placed or monitoring the display screen at that position,
Images displayed on the entire display surface can be recorded or viewed with correct electro-optical conversion characteristics.

FIG. 3 is a block diagram for explaining a modified embodiment of the present invention shown in FIG. 1. In Figure 3 7
is a movable mirror.

The light emitted from the display surface of the differential spray device 3 changes its optical path by a movable mirror 7 and reaches the brightness measuring device 4. In the display mode, the moving mirror 7 changes its set angle so that the light emitted from the display surface reaches the viewing position 8.

The viewing position 8 is a position symmetrical to the position where the luminance measuring device 4 is placed, and a recording camera is placed at this position or the screen is viewed.

FIG. 4 is a block diagram showing a further modified embodiment of the present invention. In FIG. 4, 7' is a half mirror used in place of the movable mirror 7 in FIG.

Other components are the same as those shown in FIG.

The half mirror 7' sends a portion of the light emitted from the display surface to the brightness measuring device 5 and the remaining portion to the viewing position 8. Such a modification eliminates the need for mechanical movements associated with the use of movable mirrors and the like.

Depending on the purpose of image display, it may be desirable to intentionally change the gradation characteristics of an image to display it.

For example, there is a case where only the characteristic range of density levels of an X-ray photograph is expanded to a wide gradation range. Such an operation corresponds to imparting special non-linearity to the overall gradation characteristics. According to the present invention, even such a type of image processing operation can be performed by highly accurate correction of data on the frame memory, thus demonstrating the effectiveness of the present invention.

When applying the present invention to a color image, the above-described correction may be performed for each of the three primary colors. In this case, there is no need to prepare three types of m-degree measuring instruments 4, and it is sufficient that the relative sensitivities to the three primary colors are checked and calibrated. In the calibration mode, the calibration pattern displayed on the display surface of the display device 3 may be composed of only one of the three primary colors, and the same measurement may be repeated for the other two primary colors. The thousand play devices to which the present invention is directed include:
It is not limited to CRT only. 1. For any display device that can turn off halftone display. The present invention can be applied to Furthermore, in a display device where one pixel of a display element can only display binary values and a unit area consisting of multiple pixels displays pseudo-halftones by controlling the proportion of pixels that emit or reflect light. The present invention is also applicable.

-Effects- As explained above, one aspect of the present invention is temporal.

Since it is possible to eliminate the fluctuation factor of a display device having electro-optical conversion characteristics that vary spatially, it is very effective for image display systems that require highly accurate electro-optical conversion characteristics.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the present invention, FIG. 2 is a block diagram showing an example of a calibration pattern displayed on a display device, and FIGS. 3 and 4 are main parts showing other embodiments of the present invention. It is a block diagram. l...Microprocessor, 2...
Frame 9 Memory, 3...Display device, 4...Brightness measuring device, 5...Storage device,
7... Loe moving mirror, 7'... Half mirror 18... Viewing position. Patent applicant Konishiroku Photo Industry Co., Ltd.

Claims (1)

[Claims] 1) A display image for calibrating brightness unevenness is switched and displayed on a CRT display device for each screen coordinate, a change in brightness of the display image for calibration with respect to each screen coordinate is detected, and each screen coordinate is determined from the detected value. 1. A method for automatically correcting electro-optical conversion characteristics, comprising correcting spatial variations in brightness or density on a display screen by subjecting a brightness signal to correction. 2) A display device for displaying a display image memory and data stored in the display image memory in color and monochrome image display systems. A brightness measuring device that measures the brightness of an image displayed on the display device, a storage device that stores an output signal of the brightness measuring device, operation control of the display image memory and the storage device, and the display image memory and the storage device. The microprocessor calibrates the electro-optical conversion characteristics of the display device from the luminance measurement value, and calibrates the electro-optical conversion characteristics of the display device based on the luminance measurement value. An automatic electro-optical conversion characteristic correction device characterized in that when displaying, the data of an image to be displayed is corrected based on the calibrated electro-optical conversion characteristics. 3) An electric-light conversion characteristic automatic correction device in the image storage unit according to claim 2, wherein the display image memory is a frame memory and a line memory. 4) An automatic electro-optical conversion characteristic correction device according to claim 2, characterized in that a movable mirror for optical path switching is installed between the display device and the luminance measuring device. 5) An automatic electro-optical conversion characteristic correction device according to claim 2, characterized in that a half mirror is installed between the display device and the luminance measuring device.