JPH0640255B2 - Image signal processor - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an image signal processing apparatus for performing color conversion processing of a color image signal in accordance with the characteristics of a color image output apparatus and outputting the color image signal.

[Technical background of the invention and its problems]

Recently, various color image output devices such as a CRT color display, a color copying machine, and a color printer have been put into practical use. When a color image is output with good color reproducibility using such a color image output device, it is necessary to appropriately perform color conversion processing on the color image signal according to the characteristics of the output device. This color conversion processing generally requires parallel processing of a plurality of image data (each color signal component) expressing one pixel of the image, regardless of the image processing method of the color image output apparatus. As shown, an image signal processing system corresponding to each color component is provided in parallel. That is, each image signal processing system performs color conversion processing for each color component in accordance with the output characteristics of the color image output device 2 from the color image signal input by the color image input device 1. A / D converter 3 for digitizing the color signal, and a correction circuit for correcting the output of the A / D converter 3 for the level difference and shading of the color signals due to the characteristics of the color image input device 1.
4, a color conversion matrix circuit 5 that performs color conversion processing on the color signals according to the output characteristics of the color image output device 2 (this circuit, Conversion), and a density conversion circuit 6 for controlling the density of the color signals according to the output characteristics of the color image output device 2, a filter circuit 7 for filtering these converted color signals, and the output thereof. 2
It is composed of a binarizing circuit 8 for digitizing. The binarization circuit 8 is composed of a dither circuit or the like, and is capable of forming a multi-gradation color image by the color image output device 2 capable of only binary expression. However, when the color image output device 2 is capable of expressing an intermediate value, the binarization circuit 8 is omitted and the output of the filter circuit 7 is directly given to the color image output device 2.

However, when the image signal processing systems are configured in parallel in this way, the device configuration becomes complicated, and it is unavoidable that the device becomes a large-scale device and becomes expensive.

Therefore, as shown in FIG. 2, before and after the image signal processing system,
It is considered that a multiplexer 9 and a demultiplexer 10 are provided to time-division the color image signal for each pixel, and the time-division color image signal is time-division processed by one image signal processing system. However, as shown in FIG. 3 (a) for each color signal of one pixel output in parallel, and in FIG. 3 (b) for the time-division-processed image signal, input of each color signal of the time-division color image signal. Since the interval becomes faster, it is necessary to increase the processing speed of the signal processing system accordingly. In particular, the color conversion matrix circuit 5 has to execute the product-sum operation of each color signal and the color conversion parameter within the signal transfer time for one pixel, and it is necessary to considerably increase the processing speed. Therefore, it is considerably difficult to realize the color conversion matrix circuit 5.

[Object of the Invention]

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a highly practical image capable of easily and effectively performing color conversion processing on a time-divided color image signal. It is to provide a signal processing device.

[Outline of Invention]

According to the present invention, every time a time-division signal for one pixel of a time-division color image signal obtained by time-divisionally extracting a color component of each pixel of a color image is stored in a shift register, the time division for the one pixel is performed from the shift register. Input color signals all at once and latch,
The latched time-division color signal for one pixel is repeatedly input to the product-sum calculation circuit time-division, and the product-sum calculation with the color conversion parameter is executed to obtain the color-converted color signal. It is a thing.

〔The invention's effect〕

Thus, according to the present invention, each time each color signal for one pixel of the time-division color image signal is stored in the shift register, the shift register is latched and kept within the transfer period for one pixel of the time-division color image signal. Hold this, and sequentially input this to execute the sum of products operation with the color conversion parameters, so you can easily
In addition, it is possible to efficiently perform color conversion processing of a color image. Moreover, since the color conversion processing is executed in pixel units, it is easy to set the operation timing, which is also advantageous in terms of processing speed. Therefore, practically great effects such as simplification of the structure can be obtained.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a schematic configuration diagram of the apparatus of the embodiment, which is used, for example, as the color conversion matrix circuit 5 of the image signal processing system shown in FIG. A time-division color image signal obtained by selectively extracting components in a time-division manner is input, and the time-division color image signal is subjected to color conversion processing and output.
Further, FIG. 5 shows the operation timing.

Then, the time-division color image signal is input to the shift register 11 whose transfer operation is controlled by the clock φ1,
The data is transferred in the shift register 11 in synchronization with the time division timing. Latch circuit 12 which operates by receiving a clock φ2 synchronized with the transfer period of one pixel of the color image signal
When a color signal for one pixel is input to the shift register 11, the color signal for one pixel is collectively input and latched, and held for the period of the transfer cycle for one pixel.
The selector 13 operates in response to the clock φ3, repeatedly selects each of the color signals latched by the latch circuit 12 and outputs the selected color signal to the product-sum operation circuit 14, which then operates via the selector 13. Then, the product-sum operation between the color signals repeatedly selected by time division and the color conversion parameter given from the parameter circuit 15 is executed to execute the color conversion processing of each color signal. The parameter circuit 15 sequentially outputs the parameters required for color conversion processing in synchronization with the clock φ3, and the product-sum operation using this color conversion parameter is the transfer cycle for one pixel of the time-division color image signal. It is supposed to be done inside.

Now, however, the color image signal is composed of three color components of yellow Y, green G, and cyan C, and these are converted into magenta M, yellow Y, and cyan C color components that match the output characteristics of the color image output device 2. Color conversion shall be performed. In this case, the color conversion process is performed by the color conversion parameter A (a11, a
12, a13, a21, a22, a23, a31, a32, a33) to perform the following product-sum operation.

The shift register 11 is used for this color conversion processing.
The color signal (Y, G, C) for one pixel is composed of three stages of registers in order to obtain the color signal (Y, G, C) for one pixel.
Each time it is obtained, it is input in parallel and latched. Therefore, the color signal (Y, G, C) for one pixel is simultaneously stored in the latch circuit 12 for each image signal transfer cycle for one pixel, and held for the entire transfer period. .

The clock .phi.3 is set to a frequency three times as high as the clock .phi.1 so that the parameter A is read out sequentially from the parameter circuit 15 during the transfer period of the color signal for one pixel. 13 cyclically selects. As a result, the color signal and the color conversion parameter necessary for the color conversion processing are sequentially supplied to the sum-of-products circuit 14. The product-sum operation circuit 14 is composed of, for example, TDC1010J (model number) manufactured by TRW, and is composed of a multiplier and an adder for cumulatively adding the multiplication outputs. The above-described product-sum operation is executed by the product-sum operation circuit 14 having such a configuration, and the color-converted signals (M, Y, C) are obtained and sequentially output.

As described above, according to the present invention, since each color signal of the time-division color image signal is handled on a pixel-by-pixel basis for color conversion processing, the desired color conversion processing can be executed easily and efficiently. . Moreover, the signal processing speed does not need to be unduly increased, the device can be simply configured, and its practical advantage is great.

The present invention is not limited to the above embodiment. For example, in the embodiment, the color signal composed of (Y, G, C) is converted into the color signal composed of (Y, M, C), but (W, Y, C
The color signal consisting of C) is converted to (R, G, B),
In addition, the color signal composed of (Y, I, Q) is (YR, Y-
G, Y-B) may be color-converted into color difference signals. Further, the number of color signals expressing a color image signal is not particularly limited. Also, as the latch circuit 12, SN7 of TI
The selector 13 can be omitted by using an output selection function such as 4S374 (model number). In short, the present invention can be variously modified and implemented without departing from the scope of the invention.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional apparatus, FIG. 2 is a block diagram of apparatus for time-division processing of color image signals, FIG. 3 is an operation timing chart for showing problems in time-division processing, and FIG. FIG. 5 is a schematic configuration diagram of an embodiment apparatus of the present invention, and FIG. 5 is a diagram showing operation timing of the embodiment apparatus. 5 …… Color conversion matrix circuit, 11 …… Shift register, 12 …… Latch circuit, 13 …… Selector, 14 …… Multiply-sum operation circuit, 15 …… Parameter circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 9/64 Z 8942-5C

Claims (2)

[Claims] 1. A shift register to which a time-division color image signal obtained by time-divisionally extracting color components of each pixel of a color image is supplied, and a time-division color signal for one pixel is stored in the shift register, A latch circuit to which the time-division color signals for one pixel are collectively supplied and latched from the shift register, a conversion processing circuit that performs conversion processing for converting a color signal into another color signal, and a latch circuit that is latched by the latch circuit. And a transfer means for repeatedly transferring the time-division color signal for the one pixel to the conversion processing circuit in a time-division manner. 2. The transfer means synchronizes with a parameter for conversion processing sequentially given to the conversion processing circuit during a period in which a time-division color signal for one pixel is latched in the latch circuit, The image signal processing apparatus according to claim 1, wherein the time-division color signals for pixels are repeatedly selected in a time-division manner and are applied to the conversion processing circuit.