JPH03255797A - Color picture reproducing device - Google Patents

Abstract

PURPOSE:To obtain a color picture output equipped with satisfactory brightness by detecting a white level by processing a color picture signal, and exerting gammacorrection so that the white level can be outputted brightly. CONSTITUTION:The color picture signal from a still video(SV) 1 is inputted to a color conversion circuit 2 and converted to RGB signals according to luminance and color difference signals or outputted as it is when the color picture signal is the RGB signal from the beginning. Next, the signal is digitized by an A/D converter 3 and fetched into a memory 4. By fetching the picture signal, which is fetched into the memory 4, into a CPU 8 and executing a processing such as the gamma correction, the maximum level of the picture signal is detected and the brightness of the picture is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image reproducing device that digitizes a color image signal from an Sv (still video), etc., captures it in a memory, performs brightness correction, and visualizes it. It is something.

[Prior Art] Conventionally, in order to visualize the image signal output from the Sv, the image signal from the Sv has been digitized, taken into a memory, subjected to predetermined signal processing, and printed in color as it is.

[Problems to be Solved by the Invention] However, the images captured by the S left camera include images that are almost overexposed and underexposed, so if the images are printed out as is, the images will be too blown out or overlaid. There was a drawback that it could be stored away.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a color image reproducing device configured to appropriately perform brightness correction and express the colors of an image in a good condition when visualizing a color image.

[Means to solve the problem]

A color image reproducing apparatus according to the present invention includes a peak detection means for performing predetermined nonlinear correction on a given color component signal and detecting a maximum level in the color component signal, and a detection output of the peak detection means. and a correction means for correcting the color balance of the color component signals accordingly.

[Function] The present invention detects the maximum level of the image signal and corrects the brightness of the image by importing the image signal into the memory into the CPU and performing signal processing such as γ correction. be.

[Example] Hereinafter, the present invention will be described in detail based on Examples.

Figure 1 is a block circuit diagram showing one embodiment of the present invention. In this figure, a color image signal from an SV (still video) 1 is input to a color conversion circuit 2, and is converted from a luminance/color difference signal to an RGB signal.

If it is an RGB signal from the beginning, it is output as is.

Next, the A/D converter 3 digitizes the memory 4.
be taken in.

The signal from the SVI shown in FIG. 1 has characteristics as shown in FIG. 2, and the relationship is S2 output=(light amount) 046. This is because it is an NTSC signal. Therefore, the signal captured in the memory 4 is
In order to obtain a linear relationship as shown in the figure, it is necessary to perform a 2.2 power correction on the input signal as shown in FIG.

Therefore, in this embodiment, R is sent from the memory 4 to the CPU 8.
The data of each GB is imported and shown in Figure 3.
Apply square calculation correction. Next, a histogram as shown in FIG. 5 is obtained using the corrected RG-B data. At this time, the buffer 10 is used. As a result, each of the RGB maximum signal levels S, , S2 . Detect S. In the example shown in FIG. 5, since SI>82>S3, γ (gamma) correction as shown in FIG. 6 is performed using the maximum signal level S1 of R. That is, the γ correction circuit 5 performs γ correction such that the maximum output is achieved when the input level is 31. In other words,
The γ correction circuit 5 shown in FIG. 1 has the conversion characteristics shown in FIGS. 3 and 6.

For example, if the digital signal is 8 bits, this signal level S1 will have a value of 255, and will be output as a bright portion.

In order to perform the above-mentioned brightness correction on the data R, G, and B stored in the memory 4, the γ correction circuit 5 has R'=(255/
S, )・255・(R/255) 2”G'=(255
/S+)・255・(G/255)”・2B'= (2
55/S + )・255・(B/255) The calculation results of 2g are stored as a table (.

A logarithmic correction circuit 6 at the next stage performs logarithmic conversion to obtain density data Y (yellow), 9M (magenta), and C (cyan), and a masking circuit 7 performs calculations to remove color turbidity. A printer part 9 of a color copying machine performs color printing.

Large Jl property λ It is also possible to combine the γ correction circuit 5 and the logarithmic correction circuit 6 shown in FIG. 1 into one table, thereby simplifying the circuit.

When outputting to the color monitor 12 as shown in FIG. 7, a coefficient of (255/S, By inputting the multiplied straight line as shown in FIG. 8 into the table 11 and outputting it to the color monitor 12, a natural output screen can be obtained.

K standing IL In Fig. 1, each maximum signal level S of R-G-B signals
, ,S, ,S, (FIG. 5), although a histogram was created to detect ,S,, it is also possible to use a software peak detector.

[Effects of the Invention] As explained above, according to the present invention, the white level is detected by processing a color image signal, and good brightness is achieved by performing γ correction so that the white level is output brightly. It is possible to obtain a color image with specific power.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the output signal characteristics of SV (still video), Fig. 3 is a diagram showing the SV multiplication signal correction curve, and Fig. 4 is a diagram showing the SV (still video) output signal characteristics. Figure 5 is a diagram showing the relationship between the input light amount and the signal after correction. Figure 5 is a diagram showing the histogram of the RGB signal obtained from the signal after correction. Figure 6 is γ correction for correcting the white level (brightness). FIG. 7 is a block diagram showing an embodiment for outputting a corrected image signal to a color monitor, and FIG. 8 is a diagram explaining correction for outputting a corrected image signal to a color monitor according to another embodiment of the present invention. It is a figure showing a table. 1... Sv (still video), 2... Color conversion circuit, 3... A/D converter, 4... Memory, 5... γ correction circuit, 6... Logarithmic correction circuit, 7 ...Masking circuit, 8...CPU, 9...Part of printer of color copying machine, IO...Correction table, 11...Color monitor. Li Figure 4 Figure 5 Figure 2 Figure 3 Figure 6

Claims (1)

[Claims] 1) peak detection means for performing predetermined nonlinear correction on a given color component signal and detecting the maximum level in the color component signal; A color image processing apparatus comprising: a correction means for correcting the color balance of the color component signal.