Contrast adjusting circuit
First Claim
1. A contrast adjusting circuit comprising a video data calculating section comprising a subtraction circuit for subtracting central point data Xc from input video data X, a multiplying circuit for multiplying output data from the subtraction circuit by a slope A and an adding circuit for adding central point data Yc to output data from the multiplying circuit to obtain output video data, designed for obtaining output video data Y by substituting the input video data X, the slope A and the central point data Xc and Yc in a calculation formula, Y=A·
- X+Yc−
A−
Xc, where the input video data is given as X, X_>
=—
0;
the output video data after contrast adjustment as Y, Y_>
=—
0;
the slope variably set for contrast adjustment as A, A_>
—
0;
the central point data as Xc and Yc, Xc_>
—
0 and Yc_>
—
0, an average luminance calculating section for obtaining the average luminance level of an image during an n-frame period, n being an integer of 1 or more, and a data converting section comprising a look-up table that outputs the corresponding central point data, Xc and Yc, by using the average luminance, obtained by the average luminance calculating section, as an address, for converting the average luminance level obtained by the average luminance calculating section to the corresponding central point data, out of a plurality of predetermined central point data, wherein the central point data Xc and Yc to be outputted from the data converting section are used as the central point data to be inputted to the video data calculating section.
2 Assignments
0 Petitions
Accused Products
Abstract
A contrast adjusting circuit used in a PDP display prevents the image from being whitish by suppressing the rise of the luminance at a low level when the contrast is heightened and optimally adjusts the contrast of the images always varying with time. The circuit contains an average luminance calculating section (12), an LUT (14), and an output video data calculating section (16), wherein the average luminance calculating section (12) determines the average luminance level APL for n frame images from the input video data X (X>=0) on the X-Y coordinate system, the LUT (14) determines central value data Xc, Yc from the APL, and the output video data calculating section (16) determines the output video data Y (Y>=0) collected after the contrast is adjusted according to the calculation formula Y=A·X+Yc−A·Xc where A (A>0) is the slope variably set for contrast adjustment, whereby the rise of the luminance at a low level when A is increased and the contrast is heightened, is suppressed to adjust the contrast corresponding to the APL for frame images.
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Citations
6 Claims
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1. A contrast adjusting circuit comprising a video data calculating section comprising a subtraction circuit for subtracting central point data Xc from input video data X, a multiplying circuit for multiplying output data from the subtraction circuit by a slope A and an adding circuit for adding central point data Yc to output data from the multiplying circuit to obtain output video data, designed for obtaining output video data Y by substituting the input video data X, the slope A and the central point data Xc and Yc in a calculation formula, Y=A·
- X+Yc−
A−
Xc, where the input video data is given as X, X_>
=—
0;
the output video data after contrast adjustment as Y, Y_>
=—
0;
the slope variably set for contrast adjustment as A, A_>
—
0;
the central point data as Xc and Yc, Xc_>
—
0 and Yc_>
—
0, an average luminance calculating section for obtaining the average luminance level of an image during an n-frame period, n being an integer of 1 or more, and a data converting section comprising a look-up table that outputs the corresponding central point data, Xc and Yc, by using the average luminance, obtained by the average luminance calculating section, as an address, for converting the average luminance level obtained by the average luminance calculating section to the corresponding central point data, out of a plurality of predetermined central point data, wherein the central point data Xc and Yc to be outputted from the data converting section are used as the central point data to be inputted to the video data calculating section.
- X+Yc−
-
2. A contrast adjusting circuit comprising a video data calculating section designed for obtaining output video data Y by substituting input video data X, slope A and central point data Xc and Yc in a calculation formula, Y=A·
- X+Yc−
A·
Xc, where the input video data is given as X, X_>
=—
0;
the output video data after contrast adjustment as Y, Y_>
=—
0;
the slope variably set for contrast adjustment as A, A_>
—
0;
the central point data as Xc and Yc, Xc_>
—
0 and Yc_>
—
0, wherein the video data calculation section is designed to obtain the output video data Y by a calculation formula Y=A·
X+Xc·
(1−
A), which is introduced from the calculation formula Y=A·
X+Yc−
A·
Xc by setting Yc=Xc. - View Dependent Claims (3, 4, 5, 6)
- X+Yc−
Specification