JPH0333894A - Picture data read circuit - Google Patents

Abstract

PURPOSE:To save the capacity of a picture memory by reading picture data in a picture area whose brightness is determined according to a vertical position based on an output from a vertical position counter, and reading the same picture data with respect to picture elements with the same vertical positions. CONSTITUTION:A picture element position specifying means 4 discriminates that the position of a currently scanned picture element and its display region is in a first or second area, and a read means corresponding to the area reads picture data out of the picture memory 10. If it is in the first area, picture data varies with the picture element position determined by vertical and horizontal position, and picture data is read out based on the position of the picture element concerned. If it is in the second area, the picture data are identical even if the horizontal position varies; therefore picture data is read out based on the output from the vertical position counter 2. Consequently, the number of picture data used for displaying on one screen is reduce. Thus, the capacity of the picture memory is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading circuit that reads image data from an image memory and displays it on a display means such as a CRT (cathode ray tube).

Such devices are used in various imaging devices, one of which is, for example, a thermal imaging device.

This thermal imaging device captures the infrared rays emitted from each part of an object, performs signal processing, and converts changes in the amount of infrared rays into changes in brightness for display. The human-powered infrared energy values are temporarily stored in an image memory pixel by pixel, and then the energy value data is read out and displayed on a CRT. At that time, conventional devices have been implemented that display on the same screen a gray scale that represents the correspondence between the brightness and the amount of incident infrared rays, and an offset indicator that represents the amount of offset defined as the level of the lowest energy being observed. There is.

However, in conventional devices, all of the pixel data displayed on one screen was allocated to each address of the image memory, which limited the saving of memory capacity.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image data reading circuit that can further save the memory capacity of an image memory.

In order to achieve the above object, the present invention provides a first image area whose image data is determined by a vertical position and a horizontal position;
An image data reading device for reading image data from an image memory and displaying an image having a second image area in which image data is determined by a vertical position on an image display means, comprising: a television synchronization generator; and a television synchronization generator. a vertical position counter that outputs a count value of horizontal synchronization pulses output from the horizontal position counter; a horizontal position signal generation circuit that generates a signal representing the horizontal position based on the horizontal synchronization pulse; pixel position specifying means for determining a display pixel position based on an output of a position signal generating circuit and specifying the image area corresponding to the pixel position; and a first unit for reading image data from the image memory based on the pixel position. a readout means for reading out image data from the image memory based on the output of the vertical position counter; and a second readout means for reading out image data from the image memory based on the output of the vertical position counter; and switching means for switching to the second reading means if the read area is the second image area.

According to the configuration of the present invention, first, the pixel position specifying means determines the pixel position being scanned and whether the area in which the pixel is displayed is the first area or the second area. Ru.

Then, image data is read out from the image memory by a reading means corresponding to the area. At this time, in the case of the first area, since image data differs for each pixel position determined by the vertical position and horizontal position, the image data is read out based on the pixel position. Furthermore, in the second area, the image data is the same even if the horizontal position is different, so the image data is read out based on the output of the vertical position counter.

Example Embodiments of the present invention will be described below with reference to the drawings.

Note that an image readout circuit suitable for the above-mentioned thermal imaging device will be described here as an example.

In FIG. 1, (1) is a television (hereinafter referred to as "TV") synchronization generator. (2) is a vertical position counter that counts the number of pulses of the horizontal synchronization signal output from the TV synchronization generator (1), and the count value is stored in the TV line decoder PROM (programmable read only memory) (3 ) address lines.

In addition, in the case of NTSC mode, the vertical position counter (2) performs a counting operation until the 525th horizontal synchronization pulse is manually input, while in the case of PAL mode, it performs a counting operation until the 625th horizontal synchronization pulse is input. . 1
When the scanning of the frame is completed, a reset is applied and the count value is initialized. The changeover switch (14) is N.
This is a switch that changes between TSC mode and PAL mode. Note that the case of the NTSC mode will be explained below.

By the way, there are generally two types of scanning methods for TVs: a progressive scanning method in which scanning is performed sequentially starting from the first horizontal scanning line, and a coarse screen scanning method in which horizontal scanning lines are skipped every other tree.
There is an f-interlace scanning method that completes the scanning of I sheets by repeating the scanning process several times. Here, image data compatible with the ink-lace scanning method is read out.

A conversion table as shown in FIG. 2 is stored in the TV line decoder F ROM (3). The TV line decoder F ROM (3) groups the four-tree horizontal scanning lines into one set according to this table, and outputs common data to each horizontal scanning line included in the same group. However, since it is an increment scanning method, the two horizontal scanning lines from the top of the display screen are scanned at the 264th position, and the fourth horizontal scanning line from the top is scanned at the 265th position, so <1.2
64.2.265>, and similarly <3
．． 266, 4.267>...

A black level designation signal is output for groups in which all parts of the group that are displayed by horizontal scanning lines are black, and grayscale, offset indicators, and thermal images are displayed on the displayed horizontal scanning lines. For groups containing , the group numbers are output in order from the top of the display screen.

On the other hand, the frequency dividing circuit (5) divides the horizontal synchronization signal output from the TV synchronization generator (1) into a certain specific frequency. This is the pixel data lined up on the horizontal scanning line in image 1? A
This is done to create the timing to read from M. In other words, in FIG. 4, for example, 30
When displaying 0 pixel, horizontal synchronization pulse ()ip)
The frequency is divided so that 300 pulses (Dl) are output from the frequency dividing circuit (5) after the horizontal blanking pulse (llp) for one pulse.Next, the horizontal position counter (6) The number of pulses of the output signal is counted, and the count value is sequentially supplied to the address of the address conversion FROM (4).

Address conversion FROM (4) is TV line decoder P
Based on the signal output from the ROM (3) and the signal output from the horizontal position counter (6), first the area of the pixel being scanned is a black level area and a gray scale area.

Specify whether it is an offset indicator area or a thermal image area. If the pixel area is a black and healthy area, a high level signal is output from the terminal (D3). In addition, if it is a grayscale area, the terminal (DI) (D2)
(D3) Make everything Lore Le. If it is an offset indicator area, set the terminal (l]1) to high level 1.
Terminals (D2) and (D3) are set to low level. Further, in the case of a thermal image area, the terminal (DI) (D3) is set to a low level, and the terminal (D2>) is set to a high level, and an address in the image RAM QO corresponding to the pixel position is outputted from a terminal (D4).

That is, the terminal (Dl) outputs a signal specifying whether the area is an offset indicator area or a grayscale area, and the terminal (D2) outputs a signal specifying whether the area is a thermal image area, an offset indicator area, or a grayscale area. , and the terminal (D3) outputs a designation signal indicating whether or not the area is in the black and healthy area.

When the high level signal output from the terminal (D3) is input to the T correction FROM (10), which will be described later, the γ correction FROM
The brightness level signal output from the image RAM (O+) is at the black level regardless of the signal from the image RAM.

The signal output from the terminal (D2) is passed through the flip-flop (
7) Manpower. When this signal is at a low level, the output line Q is at a low level and the output line q is at a high level, and data is not output from the latch circuit (9) but only from the latch circuit (8). Conversely, when the output line Q is at a high level, the output line Q is at a high level and the output line page is at a low level, the launch circuit (8) does not output a signal, and the latch circuit (9) outputs a signal.

As shown in FIG. 7, the image RAM θ0) has address 0.
Thermal image data is stored between address and address a9. Furthermore, address 81 and address a
Grayscale data between address 1+α, address a
, +α and the old address β, the data of the offset indicator is stored in memory, respectively. Then, the contents of the address specified by the signal from the latch circuit (8) or the latch circuit (9) are output.

The latch circuit (9) connects the terminal (
When q) is low level, address change IAFROM (4)
The signal output from the terminal (D4), that is, the image RA
The address where the image data of the pixel currently scanning the thermal image area at I'l 00) is stored is output. At this time, as shown in FIG. 7, addresses 0 to a1 are output.

Furthermore, when the terminal (attenuation) of the flip-flop (7) is at a low level, the latch circuit (8) stores the address where the image data of the pixel currently scanning the grayscale or offset indicator area in the image RAM 00) is stored. Output. Here, since the horizontal display content is the same in the gray scale area and the offset indicator area, the display content can be obtained based only on the vertical position information. Therefore, this device uses a vertical position counter (
The address in image RAM 00) is specified based on the output from 2). In the case of a gray scale area, the latch circuit (8) adds a signal from the vertical position counter (2) to a signal representing the address (al) and outputs the result.

Further, in the case of the offset indicator area, the signal from the vertical position counter (2) is added to the address (al+α) and output.

In this way, the address where the display content of the pixel being scanned is stored is specified, and the image RAM 00) outputs image data representing the content.

The γ correction PROMQD stores a conversion table for converting image data input from the image RAM Oω into brightness values of a television picture tube, and outputs brightness values corresponding to the image data. However, if the signal output from the terminal (D3) of address conversion FROM (4) is high level,
It outputs a black level luminance signal regardless of the image data.

After that, the output signal of T correction F ROM (I 1) is D
/^Converter 02) performs D/A conversion and input to cpr 03). The image is then displayed on the CR701.

Next, the operation of this apparatus will be described in the case where an image divided into regions as shown in FIG. 3(a) is displayed.

FIG. 3(0)) is an enlarged view of the area within the dashed line frame in FIG. 3(a), and the numbers in the figure indicate the horizontal scanning line number Nα during increment scanning. Also, the area ■ in the figure is shown in Figure 3 (
This corresponds to area a).

This area has No, 1 to N1133, and No,
264~N.

Up to 296 horizontal scan lines are included, all of which must be displayed at black level. Therefore, the count value supplied from the vertical position counter (2) is 1 to 3.
3 and 264 to 296, a high level signal is output from the output terminal specifying the black level. Further, this operation is similarly performed for area 0 in FIG. 3(a). Further, in area 0, four scanning lines are set as one set, and the vertical position of each set in area ◎, that is, the number of sets after entering area ◎ is output. For PAL mode, the total number of horizontal scanning lines is NTSC.
Since the number of lines is larger than that in the mode, the conversion table is created by grouping the scanning lines into groups of five. Then, the mode changeover switch 041 selects the conversion table corresponding to that mode.

According to the above-mentioned contents, TV line decoder P R
The data output from OM (3) is converted into address F.
It is supplied to the address line of ROM (4).

In addition to the data output from the TV line decoder FROM (3), horizontal position information obtained from the horizontal position counter (6) is input to the address line of the address conversion FROM (4).

Next, address conversion FROM (
The data output from 4) will be described below.

FIG. 5 is a diagram showing the input/output relationship of the conversion table stored in the address conversion FROM (4). Among human input signals, for scanning lines where the black level designation signal is at high level, addresses from address to address are specified in order, and for scanning lines where black level signal is at low level, addresses from address to address are specified in order. It has become so. Further, FIG. 6 shows the configuration of an image displayed by this apparatus, and the numbers in the figure are pixels Nα on the horizontal scanning line.

First, an address storing data corresponding to the first pixel of the horizontal scanning line Nα1 is specified. At this time, since the black level designation signal supplied from the TV line decoder P ROM (3) is at high level, address (2) in FIG. 5 is designated.

Data that makes the output line (D3) of the address conversion FROM (4) high level is written at this address, and this signal is supplied to the γ correction 1' ROM (II). As described above, the T correction PROMQI) outputs a black level luminance signal.

Next, the count value of the horizontal position counter (6) is updated and the address storing the data corresponding to the second pixel of the horizontal scanning line Nal is specified, but the same address as for the first pixel is specified. Data is output. Thereafter, addresses from address 2 to address 2 in FIG. 5 are designated in order in the same manner until the count value of the horizontal position counter (6) reaches 288.

Since all the data output during this period is the same, horizontal scanning lines No. 1 and 1 are displayed at black level as a result.

Next, the output data of the TV line decoder FROM (3) is updated, and the address storing the data corresponding to the first pixel of the horizontal scanning line Nα2 is specified, but in the same way as in the case of the horizontal scanning line Nal. Repeat the action.

Such an operation is performed for horizontal scanning lines Nα1 to Nα33 and No. 264 to No. 296, and as a result, the area shown in FIG. 3(a) is displayed in black. This process is performed similarly for area 0.

Next, the operation performed in area O in FIG. 3(a) will be described.

In this area 0, first, an address storing data corresponding to the first pixel of the horizontal scanning line Nα34 is specified.

In this case, address ■ in FIG. 5 is designated. Here, as shown in FIG. 6, the first pixel must be displayed at a black level. Therefore, data for setting the output line (D3) to a high level is written at the address (2), and this output signal causes the T correction PROM (11) to output a black level luminance signal.

After that, as the count value of the horizontal position counter (6) is updated by 1, the addresses in Figure 5 are specified in order from ■ to @, but all output data specifies the same black level. data is written. Since these data correspond to the 1st pixel to the 16th pixel, the result is horizontal scanning line No.

The 34 first to 16th pixels are displayed at black level.

Next, the address @ in FIG. 5, which stores data corresponding to the 17th pixel, is designated. This pixel is a gray scale as shown in FIG. 6, and the data output at this time and the subsequent operation will be described below.

First, the address @ in Figure 5 is the address conversion PRO old 4
) is written with data that makes the output lines (Di) (02) (03) low level. Output line (D2)
By setting the output line Q to a low level, the output line Q of the flip-flop (7) becomes a low level, and the output line q becomes a high level. As a result, no data is output from the latch circuit (9), and data is output only from the latch circuit (8).

At this time, the output line (DI) is at low level, so
This is a gray scale area, and the latch circuit (8) outputs data obtained by adding the gray scale start address (a,) (FIG. 7) to the count value of the vertical position counter (2). This data then addresses the image RAM (GO) and the grayscale data at 34 is transferred to the horizontal scan line previously written by the CPU.
Read from M0ffl. Furthermore, this image data is supplied to the address line of the γ correction PROMQI), but since the output line (D3) is at a low level, regular T correction is performed, and furthermore, the D/A converter 021
After signal processing such as /A conversion is performed, the CRTO theory is reached.

The operation described above is repeated from the 17th pixel to the 28th pixel of the horizontal scanning line Nα34, and as a result, this area becomes gray scale. During this time, the vertical position counter (
Since the output of 2) does not change, image data at the same address is always specified in image RAM0[I].

Next, since the 29th pixel to the 32nd pixel is a black area, the operation performed here is the same as when displaying the 1st pixel to the 16th pixel.

Next, address (2) in FIG. 5, which stores data corresponding to the 33rd pixel, is designated. This pixel is an offset indicator as shown in FIG. Address ■ is address conversion PI? OM(4) output line (DI)
Data is written to set the output line (D2) and (D3) to a high level and a low level to the output lines (D2 and D3). When this data is output from the address conversion FROM (4), address specification for the image RAM 00) is first performed by the output data of the latch circuit (8), as in the case of gray scale. However, in this case, since the output line (01) is at a high level, the latch circuit (8) uses the signal from the vertical position counter (2) as the starting address (a+α) of the offset indicator area in the image RAM (Fig. 7). Outputs the added signal.

In other words, the output line (Dl) is input to the most significant bit of the address line in the launch circuit (8), and by switching this signal level, the gray scale data area and offset indicator in the image R^ gate 00) are input. - The data area can be specified as appropriate.

In this way, image 1? Offcent indicator on horizontal scanning line Nα34 read from AM O[D
The data is then subjected to signal processing similar to that for grayscale data.

The above-described operation is repeated from the 33rd pixel to the 37th pixel of the horizontal scanning line target 34, and as a result, this area becomes an offset indicator. In this case, the output of the vertical position counter (2) does not change, so during this time the image R
The same address is specified in AM O■.

Next, since the 38th pixel to the 41st pixel is a black area, the operation performed here is the same as when displaying the 1st pixel to the 16th pixel.

Next, address e in FIG. 5, which stores data corresponding to the 42nd pixel, is designated. This pixel is a thermal image as shown in FIG. Address O has address change IQF
Data is written that sets the output line (D2) of the ROM (4) to a high level and sets the output line (DI) (133) to a low level. In addition, in order to read out the thermal image data of the 42nd pixel from the image RAM 00), the image RAM in which this thermal image data is stored is
00) address is written. This information is then output from line (D4).

Therefore, by specifying the address Q, the following operation is performed.

First, since the signal on the output line (D2) is at a high level, the output from the latch circuit (8) is stopped by the flip-flop (7), and the launch circuit (9) is selected.

As a result, the data output from line (D4) specifies the address of image RAM 00), and the horizontal scanning line Nα3
The thermal image data of the 42nd pixel in 4 is the image RAl'l
00).

After that, signal processing similar to grayscale data is performed.

The operations described above are repeated from the 42nd pixel to the 211th pixel of the horizontal scanning line target 34, and a thermal image is displayed in this area.

Next, since the 212th pixel to the 288th pixel is a black area, the operation performed here is the same as when displaying the 1st pixel to the 16th pixel. At this point, the readout operation of the data displayed on the horizontal scanning line Nα34 is completed.

Thereafter, as the count value output from the vertical position counter (2) is updated, the data displayed on other scanning lines is read out from the image RAM O■, but the operation is the same as for horizontal scanning line Na34. It is.

According to this device, when displaying pixels in the black level area, the γ correction P ROM (I+) is directly operated, so the image R
AMaω only needs to store image data of the thermal image area, grayscale area, and offset indicator area. Furthermore, since there is one type of image data for each vertical position in the gray scale area and the offset indicator area, one address for each vertical position is sufficient to store this image data.

Also, the address conversion FROM (4) is designed to specify addresses only for the thermal image area, but since the image data of the thermal image area is stored in the lower address in the image RAM (In), The output line (D
4) The number of terminals can be reduced.

According to the present invention, when reading the image data of the second image area whose brightness is determined by the vertical position from the image memory, the reading is performed based on the output of the vertical position counter, and the vertical position is determined based on the output of the vertical position counter. Since the same image data is read out for pixels with the same values, the number of image data required to display one screen is reduced. As a result, the capacity of the image memory can be reduced.

Furthermore, the image position designating means does not need to output a signal for designating the address where the image data included in the second Wi image area is stored in the image memory, and only designates the address for the first image area. All you have to do is output the signal. That is, in the image position specifying means,
The number of bits of the signal for specifying the address where the image data is stored can be small.

[Brief explanation of drawings]

The figures all relate to an image readout circuit that implements the present invention; FIG. 1 is a block circuit diagram thereof, FIG. 2 is a diagram for explaining the relationship between input and output in a part of the circuit, and FIG. 4 is a waveform diagram for explaining the operation of the frequency dividing circuit, FIG. 5 is a diagram showing the input/output relationship of the conversion table stored in the address conversion PROM 4, and FIG. 6 is a diagram showing a display section for explaining the read operation, and FIG. 7 is a diagram showing contents stored in the image RAM. (1) - TV sync generator. (2) - Vertical position counter (4) - Address conversion FROM Horizontal position counter (horizontal position signal generation circuit). Image 1? AM (image memory), (Il)-・γ
Correction Pl? OMD/A converter, 03)-CRT (
image display means).

Claims (1)

[Claims] (1) Image display means for reading image data from an image memory and displaying an image having a first image area where image data is determined by vertical position and horizontal position and a second image area where image data is determined by vertical position In an image data readout device for displaying image data on a screen, the apparatus includes a television sync generator, a vertical position counter that outputs a count value of horizontal sync pulses output from the television sync generator, and a vertical position counter that outputs a count value of horizontal sync pulses output from the television sync generator; and a pixel position that determines a display pixel position based on the output of the vertical position counter and the output of the horizontal position signal generation circuit and specifies the image area corresponding to the pixel position. specifying means, first reading means for reading image data from the image memory based on the pixel position, and second reading means for reading image data from the image memory based on the output of the vertical position counter.
reading means; and switching means for switching to the first reading means if the area is the first image area and switching to the second reading means if the designated area is the second image area. An image data readout circuit comprising: