JP2567227B2 - Image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention converts the gradation range of image data having gradation by a look-up table for window level conversion and displays it on the image display means. The present invention relates to an image display device.

(Prior Art) In an image display device that displays an image having digitized gradation, a desired range is selected from the range of gradations included in image data, and this range is fixed by a display unit. Display is performed according to the gradation range. Also, X
A medical image diagnostic device such as a line tomography device or a magnetic resonance tomography device can obtain 12 to 14 bits of image data, but the state of the region can be displayed most appropriately according to the region of interest of the observer. Select a range of different gradations and display them within the fixed gradation range of the display. Such data conversion is called window level conversion.

In the conventional image display device, this window level conversion is performed by a lookup table which is a data conversion table memory. The configuration of the image display device is shown in FIG. In the figure, reference numeral 1 denotes a frame buffer in which n _1- bit image data from the host processor 2 is written by a write address of the CRT controller 3, and the written image data is read by a read address of the CRT controller 3 and is looked up. Input to table 4. On the other hand, the host processor 2 writes the range to be converted (window) in the register 5 and the level to be converted in the register 6 by inputting the requirement for the window level conversion, and inputs the data to the window level control circuit 7. To do. The window level control circuit 7 rewrites the contents of the lookup table 4 based on the data. The n ₁ bit image data output from the frame buffer 1 is converted into n ₂ bit image data peculiar to the subsequent DA converter by the look-up table 4 whose contents are rewritten so as to obtain a desired window level, In the DA converter 9 via the γ correction circuit 8
Each pixel having n ₂ bits of gradation is converted into an analog image and displayed on the CRT 10. CRT controller 3
Similarly, the synchronizing signal from is analog-converted in the DA converter 9 and input to the CRT 10. Here the γ correction circuit 8 is a CRT
This is a circuit that corrects the non-linearity of the inherent density.

(Problems to be solved by the invention) In the window level conversion by this circuit, the conversion speed of the lookup table 4 (memory access speed) must be at least one pixel display speed (dot rate) to the CRT10. . If the conversion speed of the lookup table 4 is slower than the dot rate, the screen will be disturbed. Therefore, it is required to increase the conversion speed of the look-up table 4 as the dot rate increases, and if the conversion speed of the look-up table 4 cannot be met in time, parallel processing can be performed using a plurality of look-up tables 4. It becomes necessary and the circuit scale increases. In order to change the window level condition, the contents of the look-up table 4 must be rewritten so as not to disturb the display screen, for example, during the vertical blanking period. A rewrite control circuit is required.

The above problems are not limited to the case where the CRT is used as the image display means, but are common to the case where the high-speed image display means that requires gradation conversion is used for the image data to be displayed.

The present invention has been made in view of the above points, and an object thereof is to perform parallel use of a plurality of look-up tables and high-speed rewriting control of look-up tables even if the display of an image requiring gradation conversion is speeded up. It is to realize an image display device which is not necessary.

(Means for Solving Problems) According to the present invention for solving the above problems, there is provided data supplying means for supplying image data and window / level specifying data for specifying a window or a level relating to the image data, and the data supplying means. Image data conversion means for converting the image data supplied from the means into display image data based on the look-up table, and lookup for rewriting the look-up table based on the window level designation data supplied from the data supply means. Table rewriting means, image data storage means for storing the display image data given from the image data conversion means, and image display means for reading the contents of the image data storage means and displaying them as images To do.

(Operation) The image data supplied from the data supply means is gradation-converted by the look-up table of the image data conversion means, becomes display image data, is written in the image data storage means, and is read out. It is displayed as an image by the image display means. The look-up table of the image data conversion means is rewritten by the look-up table rewriting means based on the window level designation data supplied from the data supply means.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration block diagram of an embodiment of the present invention.
In the figure, the same reference numerals are used for the same parts as in FIG. Reference numeral 12 is an 8-bit frame buffer provided in the subsequent stage of the lookup table 4, which writes image data from the lookup table 4 according to the write address from the CRT controller 3 and outputs image data to the next stage according to the read address. ing.

Next, the operation of the apparatus thus configured will be described. The host processor 2 writes the window range in the register 5 and the level in the register 6 according to the setting by the input means (not shown). The window level control circuit 7 rewrites the look-up table 4 in order to select and display a desired range from the range of grayscales of 14-bit image data based on the set values from the registers 5 and 6 described above. . The 14-bit image data sent from the host processor 2 is converted from 14 bits to 8 bits by the look-up table 4 rewritten with desired data.
The data is converted to bits. Host processor 2 is CR
The T controller 3 is controlled to synchronize the raster scan timing of the CRT 10 with the image data write / read timing with respect to the frame buffer 12. The 8-bit image data output from the frame buffer 12 is corrected for density non-linearity by the γ correction circuit 8 and input to the DA converter 9, converted into an analog signal and displayed on the CRT 10.

Also, the synchronization signal from the CRT controller 3 is converted into an analog signal by the DA converter 9 and input to the CRT 10.

As described above, since the gradation is converted by the look-up table 4 and once stored in the frame buffer 12, the data conversion speed of the look-up table 4 is not affected by the dot rate of the CRT 10. ,
Only the reading speed of the frame buffer 12 needs to follow the dot rate of the CRT10. Therefore, CRT1
Look-up table 4 even if the dot rate of 0 goes up
It is no longer necessary to increase the data conversion speed or to perform parallel processing using a plurality of lookup tables 4.

Conventionally, when image data is output from the lookup table 4, the contents of the lookup table 4 cannot be rewritten in order to avoid disturbing the display screen of the CRT 10, and there is no screen display such as vertical blanking. However, in the present embodiment, since the read data from the frame buffer 12 at the time of raster scan display of the CRT 10 is structured not to pass through the lookup table 4, the contents are displayed by rewriting the lookup table 4. The screen is not disturbed, and it can be performed at any time without any restrictions such as having to select a period unrelated to the display such as the vertical blanking period.

In the above embodiment, the CRT 10 was used as a specific example of the image display means, but the image display means may have a unique gradation range and require gradation conversion for image data to be displayed. For example, image display means other than CRT may be used.

Also, the lookup table 4 is set to the frame buffer 12
The bit length stored in the frame buffer 12 may be 8 bits, which is the bit length after the data conversion by the lookup table 4, so that the memory capacity of the frame buffer 12 can be reduced.

Further, since the contents of the look-up table 4 can be rewritten when the image data is written in the frame buffer 12, the look-up table 4 can be rewritten for each specific address of the frame buffer 12 corresponding to a specific area of the screen. It becomes easier to rewrite the contents, and thus it becomes easier to divide the display screen and set the window level value for each division.

(Effects of the Invention) As described in detail above, according to the present invention, even if the display of an image that requires gradation conversion is speeded up, a plurality of lookup tables are used in parallel and a high speed rewriting control of the lookup tables is performed. An image display device that does not require is obtained.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an embodiment of the present invention, and FIG. 2 is a configuration block diagram of a conventional image display device. 1,12 ...... Frame buffer 2 ...... Host processor 3 ...... CRT controller 4 ...... Lookup table 5,6 ...... Register 7 ...... Window level control circuit 8 ...... γ correction circuit 9 ...... DA converter 10 ...... CRT

Claims (1)

(57) [Claims] 1. An image display device having a CRT display, comprising: image data supply means for supplying image data; window / level data supply means for supplying window and level data relating to the image data; Image data conversion means for converting the image data supplied from the image data supply means into display image data having a smaller number of bits than the image data based on a look-up table, and supplied from the window / level data supply means Look-up table rewriting means for rewriting the look-up table based on each window and level data, image data storage means for storing the display image data converted by the image data converting means, and the CRT display Correct the non-linearity of the concentration In this way, the image data for display stored in the image data storage means is converted, and the converted data is output by a γ correction means, and an image based on the data output from the γ correction means is converted into the CRT. An image display device characterized by displaying on a display.