JPH02271482A - Image signal processor - Google Patents

Abstract

PURPOSE:To exactly emphasize the definition by selecting a coefficient given to an S signal generating part and executing an edge emphasis by a combination of arbitrary colors. CONSTITUTION:G, B and R signals from the outside are supplied to look-up tables 21, 22 and 23, respectively, converted to signals of G', B' and R' in G, B and R spaces, respectively, and supplied to an S signal generating part 24. An output S of this S signal generating part 24 can be set to an arbitrary value by adjusting coefficients alpha, beta and tau from the outside. Subsequently, by a matrix for a blur mask, a sub signal S' is generated from the S signal, subtraction of this sub-signal S' and the main signal S is executed, and an unsharp mask signal (S - S') is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image signal processing device, and more particularly to an image signal processing device with a simple configuration and high reliability for emphasizing the sharpness of an image.

(Background of the Invention) In printed matter, it is necessary to emphasize sharpness due to a reduction in contrast due to compression of shading differences, a reduction in resolution due to halftone images, and ink bleeding.

FIG. 2 is a schematic diagram for explaining the principle of a USM circuit for sharpness enhancement. FIG. 3 is a waveform diagram showing processing waveforms in the USM circuit.

The document 1 is scanned and read by the lens 2. The read light beam is separated by a half mirror 3 into a main signal system and a sub signal system. Reference numeral 4 designates a small aperture (main aperture) that corresponds to the scan pixel of the document out of the light flux that has passed through the half mirror 3. The light flux that has passed through the main aperture 4 is focused by the lens system 5, and is then sent to the photomultiplier. (hereinafter referred to as Photomaru)
6, it is photoelectrically converted. The output of the photomultiplier 6 is amplified by an amplifier 7, a main signal 1 (■ in FIG. 3) is applied to an adder 13, and a main signal 2 is applied to one input of a subtracter 12.

Since the main signal is picked up by a small aperture, it is shown by a curve with a large slope in FIG. In addition, 8 is an aperture (USM aperture) of a hole slightly larger than the scanning pixel of the original among the light beams that passed through the half mirror 3.
The light beam passing through this 08M aperture 8 is focused by a lens system 9 and photoelectrically converted by a photomultiplier 10 (sub-signal system). The output of the photomultiplier 10 is amplified by the amplifier 11 and applied to the other input of the subtracter 12 as a sub-signal (■ in FIG. 3).

Since the sub signal is picked up by a large aperture, it is shown as a curve with a smaller slope than the main signal.

The subtracter 12 subtracts the main signal 2 and the sub signal,
An unsharp mask signal (■ in FIG. 3) is generated. Then, this unsharp mask signal and the main signal 1 are added together in an adder 13, resulting in a sharpness emphasized signal (Fig. 3 ■).
is generated. It can be seen that this sharpness emphasized signal is a signal in which the edge portions are emphasized compared to the original signal.

(Problem to be Solved by the Invention) Here, there is a difference in the reproduced image depending on which filter is used as the USM signal. Generally, the S signal is often used.

That is, a USM signal is created from the signal of the G filter, and this USM signal is added to all the main signals of yellow Y, magenta M, cyan C1 and black, thereby obtaining a signal with enhanced sharpness.

However, there have been difficulties in detecting edges in images based on shading of similar colors and in detecting edges in images with light colors.

Also, in the case of G'-G, B'-B, R'-R, G, B
, R input function may result in edge emphasis (blur) in the negative direction for combinations in hue. For example, purple and blue, green and red, red and yellow, etc.

The present invention has been made in view of the above-mentioned problems, and its purpose is to realize an image signal processing device that can accurately emphasize sharpness regardless of the type of image. .

(Means for Solving the Problems) The present invention solves the above problems in an image signal processing device for emphasizing the sharpness of an image signal. a reference table; a multiplier for receiving the outputs of these reference tables and multiplying them by coefficients provided from the outside; and a blur masking matrix for receiving a signal from the multiplication means and generating a signal for the blurring mask using the matrix;
It has a subtraction means for subtracting the output signal of the multiplication means and the output signal of the blur masking matrix, and by selecting a coefficient to be given to the multiplication means, it is possible to enhance edges with any combination of colors. It is characterized by having the following configuration.

(Function) In the image signal processing device of the present invention, by selecting the coefficients to be applied to the multiplication means, it is possible to enhance edges using any combination of colors.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram showing an example of the configuration of an embodiment of the present invention. In the figure, 21 is a look-up table (LUT) for a green signal G given from the outside, and 22 is a look-up table (LUT) for a green signal B given from the outside.
, 23 is a look-up table (LUT) for the red signal R given from the outside. 24 are coefficients α and β given from the outside.

This is an S signal generation section that generates an arbitrary combination of S signals based on γ. 25 is a blur mask matrix for generating a blur signal S', and 26 is a USM generating section that executes an operation S-8' to generate a sharpness emphasis signal.

The operation will be explained in detail below with reference to FIG.

However, the color image processing itself, which is the same as before, will be omitted.

First, external G, B, and R signals are supplied to lookup buttons 21, 22, and 23, respectively.

The input/output relationships in the lookup tables 21 to 23 are configured as follows.

G' -fg (G, b, r) B' -fb (B, g, r) R' -fr (R, g, b) Here, fg, function fb of LUT21, function fr of LUT22; Function g; arbitrary m bits b of the human input S signal; arbitrary m bits r of the input B signal; arbitrary m bits 22 of the human input R signal, respectively in G, B, R space, fg, f
The USM amount can be freely controlled using the b and fr functions, and 0
3M level is variable.

These G', B', and R' multiplied signals S signal generation section 24
is supplied to The S signal generating section 24 is applied with a G' multiplier coefficient α g /a multiplier coefficient β and an RL multiplier coefficient γ.

Therefore, S which is the output of this S signal generating section 24 is S-
αG'+βB'+γR'. Therefore, by adjusting the coefficients α, β, and γ from the outside, S can be set to an arbitrary value.

Then, the blur mask matrix 25 generates a sub signal (unsharp signal) S' from the above-mentioned S signal. Then, the USMS signal generating section subtracts the sub signal S' and the main signal S to generate an unsharp mask signal (S-3').
generate.

That is, while conventional devices generally control the USM amount using the S signal (or R signal), the device shown in this embodiment uses the coefficient (α.

β, γ) allows any combination of G, B, H (
1/2/3) can be set freely. Therefore, it is possible to accurately detect edges in images based on shading of similar colors and edges in images with light colors.

Moreover, edge enhancement in the negative direction does not occur depending on the combination of hues.

(Effects of the Invention) As described in detail above, in the present invention, edge enhancement is performed using an arbitrary combination of colors by selecting the coefficients to be applied to the S signal generation section. Therefore, it is possible to realize an image signal processing device that can accurately emphasize sharpness regardless of the type of image.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the structure of an embodiment of the present invention, Fig. 2 is a schematic diagram showing the general structure of a conventional image signal processing device, and Fig. 3 is a signal waveform when sharpness is emphasized. FIG. 1... Original 2... Lens 3... Half mirror 4... Main aperture 5... Lens system 6... Photo multiple 7...
・Amplifier 8...USM aperture 9...Lens IO...Photomaru 11・
...Amplifier 12...Subtractor 13...Adder 21...LUT (G)22...LU
T (B) 24...S signal generation section 25...Bokeh mask matrix 26...USM generation section 23...LUT (R)

Claims (1)

[Claims] An image signal processing device for emphasizing the sharpness of an image signal, comprising: a plurality of reference tables each inputting a plurality of externally applied color signals; and a plurality of reference tables receiving outputs of these reference tables. a multiplier for multiplying each coefficient by a coefficient given from the outside; a blur mask matrix for receiving a signal from the multiplier and generating a signal for a blur mask using a matrix; and an output signal of the multiplier and an output of the blur mask matrix. What is claimed is: 1. An image signal processing device comprising: subtracting means for performing subtraction with a signal, and configured to enable edge enhancement by any combination of colors by selecting a coefficient to be applied to the multiplication means.