JPS5915368A - Picture reading device - Google Patents

Abstract

PURPOSE:To control easily and accurately the color balance of a reproduced color picture to obtain good color tones, by making sampling rate for each primary color different, when the pictue data fed from a solid-state image pickup element is digitized. CONSTITUTION:The picture data transferred synchronously with the clock pulse sent from an oscillator 8 is led to an A/D converter 10 through a gate 13 and converted into a digital picture data. At the same time, the oscillation output of an oscillator 8 is supplied to a presettable counter 16. The counted value of the counter 16 is reset every time the picture data transfer clock pulse are counted and the counted value reaches the preset value. The preset value of the counter 16 is set at a proper value for each primary color in order to obtain a color balance decided by the exposure time of each primary color and through a color separating filter 5. The coincidence signal between the counted value and the preset value of the counter 16 is applied to the converter 10 as a sampling clock. Therefore, the picture data transferred by a transfer clock is converted into digital picture signals in a rate divided in frequency by the preset value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading device equipped with a solid-state image sensor used in a digital color copying device or the like, and particularly to an image reading device that improves the color balance of read image data.

Generally, in an image reading device such as a digital color copying machine that uses an image reading device equipped with a solid-state image sensor such as a charge-coupled device (CCD), the image reading device is
Usually, as shown in FIG.
The reflected light is passed through mirror 3 and lens to a color separation filter! The light is focused on a solid-state image sensor 7 which is a combination of a COD 4 and a COD 4, and is read to form image data.

Furthermore, as shown in FIG. 2, the image data formed as described above is sequentially transferred row by row in synchronization with the clock pulse from the oscillator 6, amplified by the amplifier circuit 9, and then converted into analog data. The digital image data is converted into digital image data by a digital converter lθ, and after being compared with a predetermined dither pattern and encoded by a dither circuit /l, the data is temporarily stored in the buffer memory 12.

In conventional image reading devices of this kind, color separation filters are usually provided in three types for the three primary colors R, G, and B, and when each primary color image data is read as described above, the gradation of the reproduced color image is adjusted. In order to improve the color balance, the dither pattern used in the dither circuit // in the reading system shown in the second figure may be made different for each primary color, or the light intensity of the exposure lamp l may be made different for each primary color. However, it is difficult to implement because it requires the use of a dither pattern with a complicated configuration, it is difficult to select an appropriate dither pattern, and it requires delicate adjustment of the amount of original light. The drawback was that it did not bring about significant improvement or improvements.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading device that eliminates the above-mentioned conventional drawbacks and can stably and reliably improve the color balance of reproduced color images by means that are easy to implement.

That is, the image reading device of the present invention divides the horizontal synchronization signal (H-sync) of each row of color image data using a counter preset to a different value for each primary color R, G, and B. By varying the intervals for each color, the color balance between each primary color can be improved satisfactorily.

The present invention will be described in detail below with reference to the drawings.

FIG. 3 shows an example of the configuration of the image reading device of the present invention.

In the image reading device having the configuration shown in the figure, at the start of the operation, for example, a reading signal is sent to the timing control circuit 15 from the sequence controller 11 that performs sequence control of the color laser beam printer at the timing of opening candy in the garden. Open gate/3. This read signal is ii! It is also possible to provide a sensor that detects the II image and use it as a detection output signal. The reflected light from the image is accumulated on the CCD j, and the oscillation 'a
The image data transferred in synchronization with the clock pulse from r is amplified by the amplifier circuit 9, and then passed through the gate /3 opened as described above and led to the analog-to-digital converter /θ. The images are then converted into digital image data. In addition, the oscillation output of the oscillator l is supplied to a presettable counter/6, which counts clock pulses for image data transfer and resets the value i (1) every time it reaches the preset value.The preset value of this counter/6 is , color separation filter, t, i, for example! (B) filter,
In order to obtain a color balance determined by the exposure time of each primary color by green G) filter and red @) fill, an appropriate value is set for each primary color, for example, by a sequence controller 4/4t. The coincidence output signal between the counter/6 set value and the preset value is applied to the analog-to-digital converter IO as a sampling clock, so the digital signal of the image data transferred by the transfer lock is applied to the analog-to-digital converter IO as a sampling clock. Conversion to an image signal is performed.

That is, in addition to the transfer lock pulse train as shown in Figure 1, the tumbling clock pulses for analog to digital conversion are thinned out as shown in Figure 1), and the digital image data is The arrangement of the pixel matrix is the matrix arrangement shown by the black circles in Figure 5. Note that the illustrated example shows a case where the preset value of the counter/B is set to 3.

In addition, a counter is provided in the timing control circuit 1S to calculate the clock pulses for 7 rows.For example, if the pixel column for 7 rows is 47 mm, the length of one row is as follows.
If 1 evening is mm, the built-in counter will show 24/! 1Xf-
If the argument is 7,960, the horizontal synchronization signal (11-sy
nc) to another presettable counter/g as a forming force. This counter /, 1' is preset to the same value as the counter /6 mentioned above, and can also be preset to a different value, but the coincidence output signal between the preset value and the i1 value is It is fed back to the reset input of 1 and is also supplied to the timing control circuit /j so as to perform self-reset (1).

This timing control circuit y, /3 is configured as 'R11' as shown in FIG.
- Open and close I/3. Therefore, scanning lines, that is, rows, equal to the number of clock pulses divided by the preset value described above are preset for each primary color, and the digital Il! Il image data is retrieved.

Therefore, for example, if you change the line spacing of a magenta image coarsely,
If you make the line spacing finer for yellow and cyan images,
For color images with strong magenta tones, the number of pixels within the same area of the magenta image is smaller than that of yellow and cyan images, so the color balance is reduced to suppress the strong magenta tones of the original image. A reproduced color image with smooth tones is obtained. At the same time, it is also possible to correct variations in the sensitivity characteristics of a solid-state image sensor, that is, a photoreceptor such as a CCU, for each wavelength of light. As mentioned above, by appropriately selecting the preset values of the counters for each of the primary colors R, G, and B using the sequence controller, the tones i, I! In addition, it is possible to easily correct the -1+4 degree variation of the t and 19 light bodies when printing the reproduced color image.

Note that in the configuration example described above, a single oscillator r
By dividing the oscillation output of the oscillation output, the damping point of each side tree was set.
By providing multiple oscillators of 4, //, 2,
Unlike the frequency division relationships such as //3, //g...
Even if successively different selection keys 1α are selected, the same effects as described above can be obtained. Note that the dither circuit // and buffer memory / in the configuration example shown in FIG.
, 2, the same effects as those of the conventional device a can be obtained. Furthermore, in printer output, the fact that the same effect can be obtained by thinning out as in this example can be inferred from the case of transportation.

As is clear from the above description, according to the present invention, when image data from a solid-state image sensor is digitized in an image reading device, the reproduction color can be reproduced by simple signal processing in which the sampling rate is made different for each primary color. 11
The special effect of being able to easily and accurately adjust the color balance of i (11) and obtain a good color tone is obtained.

[Brief explanation of drawings]

FIG. 1 is a layout diagram showing a schematic configuration of a conventional image reading device, FIG. 2 is a block diagram showing a detailed configuration thereof, and FIG. 3 is a block diagram showing an example of the configuration of an image reading device of the present invention. Figure 9 (4), Q3) is a waveform chart sequentially showing examples of the sampling rate setting mode, Figure S is a line diagram showing an example of the sampling mode, and Figure 6 is the timing control circuit. FIG. 2 is a block diagram showing a configuration example. L...Exposure lamp, C...Image, 3...Mirror 1, D...Lens, S...Color separation filter, 6...CCD. 7... Solid-state reading element, Z... Oscillator, 9... Level shift circuit, 10... Analog-digital converter, /C... Dither circuit, /2... Buffer memory, /3... ...gate, /lI...sequence controller, lS...timing control circuit, /l,, 1g...counter, /7. /9...preset circuit, 3, ν...7 lip-flop, n...and gate. Figure 1/2 Figure 2 Figure 6 V 5 yn c

Claims (1)

[Claims] An image reading device that includes a color separation filter and a solid-state image sensor, transfers image data obtained for each different color by the solid-state image sensor via the color separation filter, and sequentially reads the image data by locking, the image data is digitized. An image reading device characterized in that the ratio of the sampling clock to the transfer lock when performing the image reading is made different for each different color.