JP2006078552A - Image magnification device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a clearer magnified image in magnifying an image by a bilinear method. <P>SOLUTION: In order to magnify the image by the bilinear method, the image magnification device comprises; a luminance change amount detecting section 3 for detecting the luminance change amount between pixels to be magnified; an extended interpolation coefficient calculation section 4 for forming an extended interpolation coefficient by weighing the interpolation coefficient which is used in the bilinear method based on the detected luminance change amount; and an interpolation calculation section 1 for determining the luminance of the interpolation pixel by calculating interpolation using the extended interpolation coefficient which has been formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image enlarging apparatus, and more particularly to an image enlarging apparatus capable of obtaining a clearer enlarged image by using an improved bilinear method.

  2. Description of the Related Art In recent years, television receivers having functions that allow users to control various screens have been developed in accordance with technological progress. As one of such functions, there is a function of enlarging and displaying a part of a display image according to a user request. Alternatively, in some car navigation apparatuses, a display for displaying a map is provided with an image enlargement function based on user selection. When performing such image enlargement, since the original image data is small, it is necessary to interpolate the image data.

  FIG. 1 is a diagram for explaining a bilinear method that is generally used as a data interpolation method for image enlargement. For example, when the original pixels A and B are enlarged three times, it is necessary to newly interpolate two pixels between the pixels A and B. In the bilinear method, the luminance of the pixel a to be interpolated is calculated using the following interpolation formula.

Interpolation formula: a = A × (1−k) + B × k (1)
In Equation (1), k (k ≦ 1) is an interpolation coefficient, and is a value indicating the position of the pixel a as a ratio of the distance between the pixels A and B. In Expression (1), a represents the interpolation pixel, and A and B represent the luminance of the pixels A and B. As is clear from equation (1), in the interpolation method in the bilinear method, the luminance difference between the original pixels A and B is averaged in proportion to the distance between the pixels, thereby determining the luminance at the pixel at the interpolation point. Yes.

  The above-described image enlargement processing by the bilinear method generally has an advantage that an enlarged image with good image quality can be obtained with a relatively small amount of calculation. However, when there is a significant change in luminance between adjacent pixels in the image to be enlarged, for example, in one line or the edge portion of the image, the luminance is proportional to the distance between the enlarged pixels according to the bilinear method described above. Therefore, the sharpness of lines, edges, etc. is lost and the image becomes blurred. Therefore, particularly in the case of an image including a line or a sharp edge, there is a drawback that the image quality of the enlarged image is deteriorated.

  The image enlargement process using the bilinear method is described in Patent Document 1 below, and the image enlargement process using the bilinear or cubic method corresponding to the color is described in Patent Document 2 below.

JP-A-5-336346 JP2000-151990

  The present invention has been made for the purpose of solving the above-mentioned drawbacks of the conventional image enlargement apparatus in the bilinear method, and is an improved image enlargement device based on the improved bilinear method capable of performing enlargement with better image quality. The purpose is to provide.

  In order to solve the above-described problem, the first image enlargement apparatus uses a luminance change amount detection unit that detects a change amount of luminance between pixels to be enlarged and a bilinear method in order to enlarge an image by the bilinear method. The interpolated coefficient is weighted based on the detected amount of change in luminance to form an extended interpolation coefficient, and the interpolated calculation is performed using the formed extended interpolation coefficient to determine the luminance of the interpolated pixel. An interpolation calculation unit is provided.

  As an interpolation coefficient used in a general bilinear method, a value representing a position of an interpolation pixel between two pixels to be enlarged, that is, a ratio of a distance from the interpolation pixel to the two pixels is used. However, such an interpolation coefficient that depends only on the distance has the disadvantage that the luminance changes on average between the two enlarged points, and the enlarged image becomes blurred. For this reason, in this apparatus, the luminance difference between the two pixels enlarged by the luminance change amount detection unit (actually, the absolute value of the difference) is detected, and the interpolation coefficient is weighted by this value.

  By performing the interpolation calculation using the weighted interpolation coefficient reflecting the luminance difference, that is, the extended interpolation coefficient, the luminance change of the interpolation pixel is not uniform with respect to the distance. By the weighting method, for example, the luminance of an interpolation pixel arranged near a pixel having a high luminance is further increased as compared with a normal bilinear method. As a result, an enlarged image between pixels having a large luminance difference becomes sharper and image blurring is eliminated.

  According to a second device of the present invention, in the first device, a receiver that receives a TV signal and an IF-AGC voltage detection unit that detects an IF-AGC voltage in the receiver are further provided, and the interpolation calculation unit includes: When the voltage detected by the IF-AGC voltage detection unit exceeds a predetermined value, interpolation calculation is performed using an unweighted interpolation coefficient instead of the extended interpolation coefficient.

  When the reception state is bad, the electric field of the input signal is weak, so that the voltage for automatic gain control in the IF circuit unit increases. Also, if the reception condition is bad, a lot of noise appears on the screen. Since the luminance change is severe in the noise portion, if the enlargement process in the first apparatus is executed on an image containing a lot of noise, the noise is enhanced and the image quality is lowered. For this reason, in this apparatus, when the IF-AGC voltage exceeds a predetermined value, it is determined that the radio wave is a weak electric field, and the enlargement process in the first apparatus is not performed, and the enlargement process by the normal bilinear method is performed. I have to.

  As a result, in the present apparatus, it is possible to prevent occurrence of a situation in which noise is erroneously recognized as an image signal and unnecessary enhancement / enlargement processing is performed to deteriorate image quality.

  Further, if a synchronization disturbance is detected from the detection circuit output and the synchronization disturbance is equal to or greater than a predetermined value, it is determined that the multipath state is present, and the enlargement process in the first device is not performed, and the enlargement process by the normal bilinear method is performed. You may make it perform.

  Further, when the accumulated value of the luminance change amount on the screen exceeds a predetermined threshold, it is determined that the screen state is bad and there is a lot of noise, and the AGC voltage in the AGC circuit of the TV tuner is lowered. As a result, a situation in which noise is emphasized during the image enlargement processing by the first device is avoided.

  In order to solve the above problems, the second apparatus of the present invention includes an average value detection unit that detects an average value of luminance between pixels constituting an image to be enlarged in order to enlarge the image by a bilinear method, An interpolation calculation unit that determines the brightness of the interpolated pixel by performing calculations according to the bilinear interpolation formula. This interpolation calculation unit interpolates the ratio between the brightness of the pixel to be enlarged and the average value in the interpolation formula. The calculation is performed.

  As a result, a portion having a luminance higher than the average luminance of the image is further emphasized and enlarged, so that the blur of the image in the enlarged image is eliminated.

  Further, the average luminance of the image may be obtained by dividing the image into a plurality of blocks and averaging the individual blocks. As a result, the average luminance value near the pixel on which the interpolation calculation is performed is reflected in the interpolation calculation, so that a clearer enlarged image can be obtained.

  In the second apparatus, when the luminance of the pixel to be enlarged is smaller than the average value, the ratio between the luminance of the pixel to be enlarged and the average value is not incorporated in the interpolation calculation formula, and an interpolation calculation by a normal bilinear method is performed. May be performed.

  FIG. 2 is a block diagram showing a schematic configuration of the image enlargement apparatus according to the first embodiment of the present invention, and FIG. 3 is a flowchart for explaining the operation of the apparatus of FIG. In FIG. 2, reference numeral 100 denotes a pixel interpolation unit that performs pixel interpolation by the improved bilinear method according to the present invention. The interpolation calculation unit 1 calculates the luminance of the interpolation pixel according to the interpolation calculation formula, and calculates an extended interpolation coefficient described later. It has the calculating part 4 to do. Reference numeral 2 denotes a display device such as a CRT display or a liquid crystal display, 3 denotes a luminance change amount detecting unit for detecting a luminance change amount for each pixel with respect to an input video signal, and 4 denotes a detected luminance change amount. This is an extended interpolation coefficient calculation unit for calculating an extended interpolation coefficient based on.

  Hereinafter, the configuration and operation of the apparatus of FIG. 2 will be described with reference to the flowchart of FIG. In step S <b> 1, a video signal from a TV, an audio video device, a navigation device or the like is input to the interpolation calculation unit 1 and the luminance change amount detection unit 3. In step S2, the amount of change in luminance between pixels to be enlarged is detected. This detection is performed in the luminance change amount detection unit 3. Next, an extended interpolation coefficient K is calculated based on the luminance change amount detected in step S2 (step S3). This calculation is executed in the extended interpolation coefficient calculation unit 4.

  The calculation of the extended interpolation coefficient K is performed based on the following equation (2).

K = (k−0.5) × (| A−B |) +0.5 (2)
K, A, and B are the same as those in the formula (1).

  Next, in step S4, an interpolation calculation is executed using the correction correction coefficient K calculated in step S3. This interpolation calculation is executed by the interpolation calculation unit 1. The interpolation calculation formula in the interpolation calculation unit 1 is basically the above formula (1), but the extended interpolation coefficient K obtained in step S3 is substituted for the interpolation coefficient k. When the luminance of the interpolation pixel is calculated in step S4, the display device 2 is controlled according to the calculation result, and an enlarged image is displayed.

  As apparent from the above equation (2), in the apparatus of this embodiment, the value k indicating the simple distance ratio is not used as the interpolation coefficient, but the values of the pixels A and B are compared with the value k indicating the distance ratio. The bilinear interpolation is performed using the extended interpolation coefficient K weighted with the luminance difference | A−B | as an interpolation coefficient. Specifically, the interpolation calculation unit 1 performs interpolation calculation by substituting K obtained by Expression (2) for k in Expression (1).

  As a result, between the pixels A and B, the luminance of a pixel interpolated near a pixel with a high luminance becomes larger, and the luminance of a pixel interpolated near a pixel with a low luminance becomes smaller. Therefore, the brightness change of the enlarged image becomes sharper, the blurring of the image when enlarging an image or the like with a clear edge is eliminated, and the image quality is improved.

  FIG. 4 is a block diagram showing a schematic configuration of image enlargement processing according to the second embodiment of the present invention, and FIG. 5 is a flowchart for explaining the operation of the apparatus. The apparatus of this embodiment is an embodiment in the case where a TV reception signal is used as an input video signal.

  In a television receiver, when the received radio wave is weak, the video signal contains a lot of noise. Pixels displaying noise have a large luminance change before and after that. Therefore, when the image enlargement processing described in the first embodiment is performed on a video signal including a lot of noise, the result is that the noise is emphasized.

  Therefore, in the present embodiment, when the received radio wave is a weak electric field, the image enlargement process shown in FIG. 2 is not performed, and the normal bilinear interpolation process is performed. Further, in order to determine whether the received radio wave is a weak electric field, in this embodiment, when the IF-AGC voltage is detected and this voltage exceeds a preset value, image enlargement using the apparatus shown in FIG. The processing is not performed.

  In FIG. 4, 5 is a receiving antenna for television signals, 6 is an RF circuit unit, 7 is an IF circuit unit, and 8 is a detection circuit unit. The video signal output from the detection circuit unit 8 after being converted to the intermediate frequency in the IF circuit unit 7 is input to the first pixel interpolation unit 10 or the second pixel interpolation unit 11 via the switching unit 12. The first pixel interpolation unit 10 includes a luminance change amount detection unit 3 and a pixel interpolation unit 100 shown in FIG. That is, the image enlarging apparatus according to the first embodiment of the present invention. The second pixel interpolation unit 11 is an image enlargement device using a normal bilinear method, and includes an interpolation calculation unit that performs an interpolation calculation using Expression (1). The outputs of the first and second pixel interpolation units 10 and 11 are input to the display device 2 to display an image. Although not shown, the audio signal output from the detection circuit unit 8 is output as audio through a speaker.

  Reference numeral 9 denotes an IF-AGC circuit unit that adjusts an input gain of the IF circuit unit 7. The IF-AGC circuit unit 9 of this apparatus has a function of detecting whether or not the IF-AGC voltage is equal to or higher than a preset voltage and outputting the detected signal to the switching unit 12 as a switching signal.

  Next, the operation of the apparatus according to the present embodiment will be described with reference to FIG. First, when a television signal is received in step S10, the IF-AGC circuit unit 9 detects an IF-AGC voltage for the received signal (step S11). Next, it is determined whether or not the detected IF-AGC voltage is equal to or higher than a preset value (step S12). If the detection voltage is equal to or higher than the set value, it can be seen that large amplification is performed on the input signal, and therefore the received signal is a weak electric field.

  Therefore, if YES in step S12, the IF-AGC circuit unit 9 outputs a switching signal to the switching unit 12, and connects the second image enlargement unit 11 that performs normal image enlargement processing to the output of the IF circuit unit 8. To do. Therefore, in the second pixel interpolation unit 11, an interpolation calculation process using a normal interpolation coefficient by the bilinear method is executed on the output of the IF circuit unit 8 (step S13).

  On the other hand, if NO in step S12, that is, if the IF-AGC voltage does not reach the set value, it is determined that the level of the received signal is normal, and a switching signal is output from the IF-AGC circuit unit 9 to detect the detection circuit unit. The output of 8 is connected to the first pixel interpolation unit 10. As a result, the first pixel interpolation unit 10 executes the image enlargement process described with reference to FIGS. 2 and 3 (step S14). Note that the pixel interpolation processing of the present invention using the equations (1) and (2) is replaced with the pixel interpolation processing by the extended bilinear method as opposed to the pixel interpolation processing by the ordinary bilinear method using the equation (1). Call.

  As described above, since the image enlargement apparatus according to the present embodiment can select an optimal interpolation process according to the electric field strength of the received TV signal, the blurring of the video accompanying the image enlargement is improved, and noise is erroneously detected as an image. A situation in which recognition and unnecessary enlargement processing are performed can also be avoided.

  FIG. 6 is a flowchart for explaining the operation of the image enlarging apparatus according to the third embodiment of the present invention. The configuration of the present embodiment will be described with reference to FIG. If the video data input for pixel interpolation is a TV image during multi-pass, performing the pixel interpolation processing by the extended bilinear method will enhance the ghost and reduce the image quality. Therefore, the apparatus according to the present embodiment detects the reception state of the TV based on the disturbance of the synchronization signal, and performs interpolation processing by either the first or second pixel interpolation unit 10 or 11 based on this detection signal. Have decided.

  That is, the level of synchronization disturbance is detected from the output of the detection circuit unit 8, and when the level is higher than a preset threshold value, the output of the detection circuit unit 8 is connected to the second pixel interpolation unit 11 by the switching unit 12. On the other hand, when the synchronization disturbance is less than or equal to the threshold value, the output of the detection circuit unit 8 is connected to the first pixel interpolation unit 10 by the switching unit 12 to perform pixel interpolation processing by the extended bilinear method.

  Referring to the flowchart of FIG. 6, first, in step S20, a television signal is received. Next, the synchronization disturbance of the signal received in step S21 is detected, and it is determined whether the disturbance is equal to or greater than a preset threshold value (step S22). If YES in step S22, that is, if there is a synchronization disturbance greater than or equal to the threshold value, it is determined that the reception state is multipath, and in step S23, an interpolation operation by a normal bilinear method is performed. On the other hand, if NO is determined in step S22, that is, if the reception state is not multipath, pixel interpolation processing by the extended bilinear method is performed in step S24.

  As described above, the image enlargement apparatus according to the present embodiment can select an optimal pixel interpolation process depending on whether the reception state is multi-pass. In addition, it is possible to avoid a situation where enlargement processing is performed with emphasis on multipath ghosts.

  FIG. 7 is a block diagram showing a schematic configuration of an image enlargement apparatus according to the fourth embodiment of the present invention, and FIG. 8 is a flowchart for explaining the operation. When the TV radio wave is weak and the reception state deteriorates, noise increases on the screen and the luminance change amount of the video signal increases. Therefore, by observing the luminance change amount of the video signal, it is possible to estimate the reception state of the radio wave. Based on such estimation, optimal interpolation control of the AGC circuit of the TV tuner is performed, so that pixel interpolation processing by the extended bilinear method is appropriately performed.

  7, the same reference numerals as those in FIG. 2 indicate the same or similar components, and the description thereof is omitted. A television tuner 15 has an AGC circuit 16. The output of the luminance change amount detection unit 3 is accumulated in the comparison unit 17 and compared with a predetermined threshold value. The output of the comparison unit 17 is used for optimal control of the AGC circuit 16.

  The operation of the apparatus shown in FIG. 7 will be described with reference to the flowchart of FIG. First, a video signal is input in step S30, and the luminance change amount between pixels to be enlarged is detected in the luminance change amount detection unit 3 (step S31). In step S32, it is determined whether or not the cumulative value of the detected change amount is equal to or greater than a preset threshold value. If YES in step S32, that is, if it is determined that the accumulated value of the luminance change is equal to or greater than the threshold, control is performed to lower the AGC voltage of the TV tuner in step S33.

  This control is performed according to a table written in advance in a storage device or the like. Information such as increasing the AGC correction control when the accumulated value of the luminance change amount of the video signal is increased and decreasing the AGC correction control when the accumulated value is small is written in the table. When the AGC optimal control of the TV tuner is executed in step S33, pixel interpolation processing by the extended bilinear method is performed on the video signal (step S34). If NO in step S32, the accumulated value of the luminance change amount is equal to or less than the threshold value, so the AGC optimum control in step S33 is skipped, and the pixel interpolation process by the extended bilinear method in step S34 is executed.

  In the present embodiment, even if the state of the input video signal is poor and includes noise, the above process obtains an enlarged image without unnecessarily enhancing noise and without image blurring. be able to.

  FIG. 9 is a block diagram showing a schematic configuration of an image enlargement apparatus according to the fifth embodiment of the present invention, and FIG. 10 conceptually shows an image enlargement result according to this embodiment. FIG. 11 is a flowchart for explaining the operation of the apparatus shown in FIG.

  In FIG. 9, reference numeral 20 denotes a pixel capturing unit, which captures the luminance of an input video signal for each pixel and stores it in a memory. Reference numeral 21 denotes a luminance average value calculation unit, which calculates the average luminance value of the entire screen from the luminance of each pixel stored in the pixel capturing unit 20. A third pixel interpolating unit 22 sequentially reads out the luminance of the pixels stored in the pixel capturing unit 20 and performs an interpolation operation based on the read value and the average value calculated by the average value detecting unit 21. Determine the luminance of the interpolated pixel. The details of the interpolation calculation in this embodiment will be described later. Reference numeral 23 denotes a display device.

  (A) of FIG. 10 is an original screen, and the line part shown with the code | symbol 25 has a higher brightness than the average brightness of the whole screen. The case of enlarging this image according to the present embodiment will be described with reference to the flowchart of FIG. First, in step S40, a video signal is captured for pixels of the entire screen. In step S41, an average value is calculated for the luminance of the pixels on the entire screen. In step S <b> 42, the luminance information of each pixel stored in the pixel capturing unit 20 is read together with the position information, and is output to the third pixel interpolation unit 22. The third pixel interpolation unit 22 calculates a correction value for interpolation based on the read value and the average value calculated by the average value detection unit 21 (step S43).

  In the present embodiment, this correction value is represented as (A / average value), where A is the luminance of the read pixel. In FIG. 10A, since the luminance A of the line portion 25 is equal to or higher than the average value, the correction value is 1 or higher in this portion. Next, in step S44, interpolation calculation is performed based on the calculation formula of this embodiment. This interpolation calculation formula is shown in formulas (3) and (4).

When 1-k> k,
a = A × (1-k) × (A / average value) × Gk + B × k (3)
When k> 1-k
a = A * k + B * (1-k) * (A / average value) * Gk (4)
Here, k is a value indicating the ratio of the distance between the pixels A and B as in the case of the expression (1), and Gk is a gain adjustment coefficient that can be arbitrarily set. A and B indicate the luminance of the pixels A and B, and a indicates the luminance of the interpolation pixel a.

  As is apparent from the equations (3) and (4), in the apparatus of this embodiment, when determining the luminance of the interpolation pixel, (A / average value) is calculated with respect to the interpolation equation by the normal bilinear method. Weighting is performed. Therefore, when the luminance of the pixel A is higher than the average value, the value of (A / average value) is larger than 1, and the luminance of the interpolation pixel a is larger than that in the normal bilinear method. Conversely, when the luminance is lower than the average value, (A / average value) is smaller than 1, so the luminance of the interpolated pixel is smaller than that in the bilinear method. Further, the luminance of the interpolation pixel is determined such that the luminance of the interpolation pixel close to the pixel having higher luminance between the pixels A and B to be enlarged becomes larger. As a result, the line or the edge portion of the image is displayed with emphasis. Note that the degree of emphasis can be adjusted by a gain adjustment coefficient Gk that can be arbitrarily set.

  In step S44, when the luminance calculation is completed for one interpolation pixel, it is determined in step S45 whether or not all the interpolations are completed. If not completed (NO in step S45), step S42 and subsequent steps are again performed. Execute. If it is determined in step S45 that all interpolations have been completed (YES in step S45), the process ends.

  FIG. 10B shows a result when the above-described image enlargement process is performed on the image shown in FIG. As is apparent from FIG. 5B, the apparatus according to the present embodiment automatically regards a portion where the luminance is higher than the average value of the screen as an edge, and performs the enlargement process by emphasizing the portion 26 to perform enlargement. The image is not blurred at the time. Note that the pixel interpolation method based on the equations (3) and (4) is temporarily referred to as a second extended bilinear method.

  FIG. 12 is a diagram illustrating an operation flow of the image enlarging apparatus according to the sixth embodiment of the present invention. In the apparatus of the fifth embodiment shown in FIGS. 9 to 11, the average luminance value is calculated for the pixels of the entire screen and the edge enhancement processing of the enlarged image is performed. In the present embodiment, the screen is X × Y. The block is divided into a plurality of blocks, and an average value of luminance is obtained for each block to perform an interpolation calculation. As a result, since edge detection can be performed based on the average value around the pixel to be interpolated, more appropriate interpolation can be performed.

  With reference to FIG. 12, the processing procedure of the present embodiment will be described. First, in step S50, pixel information of the entire screen is captured. Next, the screen is divided into a plurality of blocks of X × Y size (step S51), and pixel information is read for the first block (step S52). The pixel information includes information on the position of the pixel and luminance information. In step S53, an average luminance value is calculated for the read block. In step S54, information of one pixel in the read block is read. In step S55, a correction value is calculated for the read pixel. In step S56, interpolation is performed by the second extended bilinear method using the correction value.

  Note that detailed processing in steps S55, S56, and S57 is the same as that in the fifth embodiment described with reference to FIG. When the interpolation calculation for the read pixel ends in step S56, it is determined in step S57 whether the calculation processing for all the pixels in the read block has been completed. If not all has been completed (NO in step S57), the process returns to step S54 to execute step S55 and subsequent steps for the next pixel.

  In the case of YES in step S57, that is, when the interpolation process is completed for all the pixels of the read block, it is determined in step S58 whether or not the interpolation process has been completed for all the blocks. If YES in step S58, the image enlargement process for the captured screen ends. In the case of NO at step S58, the process returns to step S52 to read the next block, and the processing from step S53 onward is executed on the read block.

  In the present embodiment, the block sizes X and Y and the gain Gk for adjusting the degree of edge enhancement can be arbitrarily set.

  FIG. 13 is a flowchart for explaining the operation of the image enlargement apparatus according to the seventh embodiment of the present invention. The apparatus of the present embodiment is a modification of the apparatus according to the fifth embodiment shown in FIGS. 9 to 11, and the second extension of step S44 is performed only when the luminance of each pixel is equal to or higher than the average value. Interpolation is performed by the bilinear method.

  Specifically, after calculating the correction value in step S43, it is determined whether or not the correction value is 1 or more, that is, whether or not the luminance of the pixel is equal to or higher than the average value (step S60). (NO in step S60), interpolation processing by a normal bilinear method is performed in step S61. In the case of YES in step S60, the interpolation calculation is executed by the second extended bilinear method in the same manner as in the fifth embodiment in step S44. Note that the same reference numerals in the flowchart of FIG. 13 as those in the flowchart of FIG. 11 indicate the same or similar steps, and therefore, redundant description will not be given here.

  As described above, in the image enlargement apparatus according to the present embodiment, the enhancement process is performed only on the edge portion, and the normal interpolation calculation without enhancement is performed on the portion that is not regarded as the edge portion. A clearer image can be obtained.

  FIG. 14 is a flowchart for explaining the operation of the image enlarging apparatus according to the eighth embodiment of the present invention. The apparatus according to the present embodiment is a modification of the apparatus according to the sixth embodiment shown in FIG. 12, and in the same manner as the apparatus according to the seventh embodiment shown in FIG. After that, step S70 for determining whether or not the luminance of the pixel to be interpolated is larger than the average value is provided, and only when the luminance is larger than the average value (YES in step S70), the same as step S44 in FIG. The interpolation operation by the second extended bilinear method is performed. Therefore, if NO in step S70, an interpolation calculation by a normal bilinear method is performed in step S71.

  As a result, in this embodiment, the edge portion is subjected to enhancement processing based on the average luminance value obtained for each divided block, but the non-edge portion is subjected to interpolation calculation processing that does not involve normal enhancement processing. Therefore, a clearer image can be obtained when the image is enlarged.

The figure which shows the expansion process of the image by a bilinear method. 1 is a block diagram showing a schematic configuration of an image enlargement apparatus according to a first embodiment of the present invention. The flowchart for operation | movement description of the apparatus shown in FIG. The block diagram which shows schematic structure of the image expansion apparatus which concerns on the 2nd Embodiment of this invention. 5 is a flowchart for explaining the operation of the apparatus shown in FIG. The flowchart with which it uses for operation | movement description of the apparatus which concerns on the 3rd Embodiment of this invention. The block diagram which shows schematic structure of the apparatus which concerns on the 4th Embodiment of this invention. 8 is a flowchart for explaining the operation of the apparatus shown in FIG. The block diagram which shows schematic structure of the apparatus which concerns on the 5th Embodiment of this invention. The figure for demonstrating the effect of the apparatus shown in FIG. 10 is a flowchart for explaining the operation of the apparatus shown in FIG. The flowchart with which it uses for description of the apparatus which concerns on the 6th Embodiment of this invention. The flowchart with which it uses for description of the apparatus which concerns on the 7th Embodiment of this invention. The flowchart with which it uses for description of the apparatus which concerns on the 8th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Interpolation calculation part 2 Display apparatus 3 Luminance change amount detection part 4 Extended interpolation coefficient calculation part 7 IF circuit part 9 IF-AGC circuit part 10 1st pixel interpolation part 11 2nd pixel interpolation part 12 Switching part 20 Pixel capture part 21 Average Value Detection Unit 22 Third Pixel Interpolation Unit 23 Display Device

Claims (8)

In an image enlargement device that enlarges an image by the bilinear method,
A luminance change amount detection unit for detecting a luminance change amount between pixels to be enlarged;
An extended interpolation coefficient calculation unit that weights an interpolation coefficient used in the bilinear method based on the detected amount of change in luminance to form an extended interpolation coefficient;
An image enlargement apparatus comprising: an interpolation calculation unit that performs an interpolation calculation using the formed extended interpolation coefficient and determines a luminance of an interpolation pixel. The image enlarging apparatus according to claim 1.
A receiver for receiving a TV signal;
An IF-AGC voltage detector for detecting an IF-AGC voltage in the receiver;
When the voltage detected by the IF-AGC voltage detection unit exceeds a predetermined value, the interpolation calculation unit performs an interpolation calculation using an unweighted interpolation coefficient instead of the extended interpolation coefficient, Image magnifier. The image enlarging apparatus according to claim 1.
A receiver for receiving a TV signal;
A synchronization disturbance detecting unit for detecting synchronization disturbance from the detection circuit output in the receiver;
The interpolation calculation unit, when the synchronization disturbance detected by the synchronization disturbance detection unit exceeds a predetermined value, performs an interpolation calculation using an unweighted interpolation coefficient instead of the extended interpolation coefficient, Enlarging device. The image enlarging apparatus according to claim 1.
A TV tuner having an AGC circuit;
A comparison unit that compares a cumulative value of the detected luminance change amount with a predetermined threshold;
The AGC circuit reduces an AGC voltage when the accumulated value exceeds the threshold by the output of the comparison unit. In an image enlargement device that enlarges an image by the bilinear method,
An average value detection unit for detecting an average value of luminance between pixels constituting an image to be enlarged;
An interpolation calculation unit that performs calculation according to the interpolation calculation formula by the bilinear method and determines the luminance of the interpolation pixel,
The image enlargement apparatus, wherein the interpolation calculation unit performs an interpolation calculation by incorporating a ratio between a luminance of a pixel to be enlarged and the average value into the interpolation calculation formula. The image enlargement apparatus according to claim 5,
The average value detecting unit divides the image to be enlarged into a plurality of blocks and calculates an average value for each block. The image enlargement apparatus according to claim 5,
A luminance comparison unit for comparing the luminance of the pixel to be enlarged and the average value;
The interpolation calculation unit performs the interpolation calculation without incorporating the ratio into the interpolation calculation formula when the luminance comparison unit determines that the luminance of the pixel to be enlarged is smaller than the average value. , Image enlargement device. The image enlarging apparatus according to claim 6.
A luminance comparison unit for comparing the luminance of the pixel to be enlarged and the average value;
The interpolation calculation unit performs the interpolation calculation without incorporating the ratio into the interpolation calculation formula when the luminance comparison unit determines that the luminance of the pixel to be enlarged is smaller than the average value. , Image enlargement device.

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