Source: http://www.google.com/patents/US7826680?dq=3798359
Timestamp: 2014-07-28 21:48:30
Document Index: 241451194

Matched Legal Cases: ['Application No. 60', 'Application No. 07252590', 'Application No. 07252587', 'Application No. 07252588', 'Application No. 07252589', 'Application No. 07252590', 'Application No. 0704764']

Patent US7826680 - Integrated histogram auto adaptive contrast control (ACC) - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsThe invention provides for calculating the sum of the luminance values of all pixels in each of a number of regions making up the whole image. A histogram is then created of all the sums of luminance at the end of each frame. The histogram is then rescaled such that the luminance range is normalized....http://www.google.com/patents/US7826680?utm_source=gb-gplus-sharePatent US7826680 - Integrated histogram auto adaptive contrast control (ACC)Advanced Patent SearchPublication numberUS7826680 B2Publication typeGrantApplication numberUS 11/525,276Publication dateNov 2, 2010Filing dateSep 21, 2006Priority dateJun 26, 2006Fee statusPaidAlso published asEP1874038A1, US20070297689Publication number11525276, 525276, US 7826680 B2, US 7826680B2, US-B2-7826680, US7826680 B2, US7826680B2InventorsGreg NealOriginal AssigneeGenesis Microchip Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (19), Non-Patent Citations (8), Referenced by (1), Classifications (4), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetIntegrated histogram auto adaptive contrast control (ACC)US 7826680 B2Abstract The invention provides for calculating the sum of the luminance values of all pixels in each of a number of regions making up the whole image. A histogram is then created of all the sums of luminance at the end of each frame. The histogram is then rescaled such that the luminance range is normalized. Once the histogram has been created, an appropriate transfer function is created using the integrated luminance histogram for the frame. In this way detail within significant objects in the image are enhanced since the average luminance of objects in an image are weighted more than then the luminance of individual pixels providing a more realistic transfer function.
(a) receiving a video frame formed of a plurality of pixels each having associated pixel data;
(b) generating an integrated luminance histogram for the received video frame data;
(c) generating histogram difference values in accordance with histogram values from the integrated histogram and histogram values from a flat histogram;
(d) multiplying the histogram difference values by a strength factor SF and adding resulting values to the histogram values of the flat histogram to generate conditioned histogram values;
(e) scaling and limiting the conditioned histogram values resulting from step (d);
(f) generating a transfer function in accordance with values resulting from step (e);
(g) updating the video frame data using the transfer function to enhance contrast of the video frame;
(h) providing the updated video frame to a display; and
(i) when a next video frame is received, repeating steps (a) through (f) for the next received video frame.
2. A method as recited in claim 1, wherein generating the integrated luminance histogram, comprises;
splitting the video frame into a number of regions;
generating a luminance value for each of the pixels for each region;
summing the luminance values for the pixels in each region;
dividing the summed luminance value for each region by the number of pixels in each region to generate the region luminance value; and
generating the integrated luminance histogram using the region luminance values for the video frame.
wherein the generating the pixel luminance value Yi,j for each pixel Pij in the region is accomplished according to Yi,j=(0.257 * Ri,j)+(0.504 * Gi,j)+(0.098 * Bi,j) where Ri,j, Gi,j, Bi,j, are RGB color components for a pixel Pij.
scaling the integrated luminance histogram.
5. A method as recited in claim 1, further comprising displaying the updated video frame on a display.
7. Computer program product comprising a non-transitory computer readable storage medium having computer program code instructions stored therein executable by a computer processor for adaptive contrast control, comprising:
computer code for receiving a video frame formed of a plurality of pixels each having associated pixel data;
computer code for generating an integrated luminance histogram for the received video frame data;
computer code for generating histogram difference values in accordance with histogram values from the integrated histogram and histogram values from a flat histogram;
computer code for multiplying the histogram difference values by a strength factor SF and adding resulting values to the histogram values of the flat histogram to generate conditioned histogram values;
computer code for scaling and limiting the conditioned histogram values;
computer code for generating a transfer function in accordance with values resulting from the scaling and limiting; and
computer code for updating the video frame data using the transfer function.
8. Computer program product as recited in claim 7, wherein generating the integrated luminance histogram, comprises;
computer code for splitting the video frame into a number of regions;
computer code for generating a luminance value for each of the pixels for each region;
computer code for summing the luminance values for the pixels in each region;
computer code for dividing the summed luminance value for each region by the number of pixels in each region to generate the region luminance value; and
computer code for generating the integrated luminance histogram using the region luminance values for the video frame.
9. Computer program product as recited in claim 8, wherein the computer code for generating a luminance value for each of the pixels for each region includes:
computer code for providing a pixel luminance value Yi,j for a pixel Pij according to Yi,j=(0.257 * Ri,j)+(0.504 * Gi,j)+(0.098 * Bi,j) where Ri,j, Gi,j, Bi,j, are RGB color components for a pixel Pij.
10. Computer program product as recited in claim 7, further comprising:
computer code for scaling the integrated luminance histogram.
11. Computer program product as recited in claim 7, further comprising
computer code for displaying the updated video frame on a display.
an interface arranged to receive a video frame formed of a plurality of pixels each having associated pixel data;
a histogram generator for generating an integrated luminance histogram for the received video frame data;
a histogram conditioner for generating scaled and limited histogram values�wherein the scaled and limited histogram values are generated by:
generating histogram difference values in accordance with histogram values from the integrated histogram and histogram values from a flat histogram;
multiplying the histogram difference values by a strength factor SF and adding resulting values to the histogram values of the flat histogram to generate conditioned histogram values;
scaling and limiting the conditioned histogram values;
a transfer function generator for generating a transfer function in accordance with the scaled and limited histogram values; and
a means for updating the video frame data using the transfer function.
14. An apparatus as recited in claim 13, wherein generating the integrated luminance histogram, comprises;
means for splitting the video frame into a number of regions;
means for generating a luminance value for each of the pixels for each region;
means for summing the luminance values for the pixels in each region;
means for dividing the summed luminance value for each region by the number of pixels in each region to generate the region luminance value; and
means for generating the integrated luminance histogram using the region luminance values for the video frame.
15. An apparatus as recited in claim 14, wherein the means for generating the luminance value for each of the pixels for each region includes:
means for providing a pixel luminance value Yi,j for a pixel Pij according to Yi,j=(0.257 * Ri,j)+(0.504 * Gi,j)+(0.098 * Bi,j) where Ri,j, Gi,j, Bi,j, are RGB color components for a pixel Pij.
means for scaling the integrated luminance histogram.
means for displaying the updated video frame on a display.
18. An apparatus as recited in claim 17, wherein the display is selected from the group that includes an LCD screen, an OLED screen, a DLP screen, a CRT and a plasma panel.
CROSS REFERENCE TO RELATED APPLICATIONS This patent application takes priority under 35 U.S.C. 119(e) to (i) U.S. Provisional Patent Application No. 60/816,845, filed on Jun. 26, 2006 entitled �INTEGRATED HISTOGRAM AUTO ADAPTIVE CONTRAST CONTROL (ACC)� by Neal. This application is also related to the following co-pending U.S. patent applications, which are filed concurrently with this application and each of which are herein incorporated by reference, (i) U.S. patent application Ser. No. 11/768,667, entitled �UNIVERSAL, HIGHLY CONFIGURABLE VIDEO AND GRAPHIC MEASUREMENT DEVICE� naming Neal as inventor; (ii) U.S. patent application Ser. No. 11/613,009, entitled �VIDEO CONTENT DETECTOR� naming Neal as inventor; and (iii) U.S. patent application Ser. No. 11/565,464, entitled �VIDEO WINDOW DETECTOR�, naming Neal as inventor.
SUMMARY OF THE INVENTION Broadly speaking, the invention relates to increasing the contrast for luminance levels that occur in significant areas of the image. The invention can be implemented in numerous ways, including as a method, system, device, apparatus, or computer readable medium. Several embodiments of the invention are discussed below.
DESCRIPTION OF DRAWINGS FIG. 1 shows an example medium-bright image and a histogram for the image, in accordance with an embodiment of the present invention.
Y reg = ∑ i , j = 1 M , N ⁢ Y i , j / ( M � N ) ( eq . ⁢ 2 ) An integrated luminance histogram Hint for the video frame Fs is then generated using the integrated luminance values Yreg from which a transfer function Ts is provided and applied on a frame by frame basis according to the process 600 described below.
FIG. 6 shows a flowchart detailing a process 600 in accordance with an embodiment of the invention. The process 600 begins at 602 by receiving a video frame in the form of pixel data. If, at 604, the pixel data is not YUV format, that the pixel data is converted to YUV format at 606. In any case, at 608, the video frame is split into a number of regions while at 610, a luminance value for each region is calculated based upon a summation of all pixel luminance values for each of the regions. At 612, a luminance histogram is generated that includes all regions. Next, at 614 a histogram difference value is generated by taking a difference between a particular histogram value and a flat histogram value of one (�1�). At 616, the histogram difference value is then multiplied by a strength factor SF which is then added back to the flat value. In this way, the histogram is conditioned such that a strength value of zero (�0�) results in a flat line whereas a strength value of one (�1�) results in the original histogram. At 618, the conditioned histogram values are then limited (thereby limiting the maximum slope at any point in the final transfer function) such that any histogram values above the limit are added back into the histogram by sharing them evenly. At 620, a transfer function is created by integrating the conditioned histogram by starting the transfer function at a value of 0 and then for each subsequent position, add in the corresponding value from the histogram such that a flat line histogram would give a straight line transfer function (where output values would equal input values). The transfer function is then applied at 622.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS5546474Dec 21, 1993Aug 13, 1996Hewlett-Packard CompanyDetection of photo regions in digital imagesUS5742704Jan 7, 1997Apr 21, 1998Fuji Xerox Co., Ltd.Image coding apparatus capable of coding in accordance with an image typeUS5847773Jan 3, 1996Dec 8, 1998Thomson Consumer Electronics, Inc.Video system including apparatus for deactivating an automatic control arrangementUS6393148 *May 13, 1999May 21, 2002Hewlett-Packard CompanyContrast enhancement of an image using luminance and RGB statistical metricsUS7469160 *Apr 18, 2003Dec 23, 2008Banks Perry SMethods and apparatus for evaluating image focusUS20040161152Jun 14, 2002Aug 19, 2004Matteo MarconiAutomatic natural content detection in video informationUS20050002566Oct 10, 2002Jan 6, 2005Riccardo Di FedericoMethod and apparatus for discriminating between different regions of an imageUS20050163372Oct 19, 2004Jul 28, 2005Shingo KidaVideo signal processor and method of processing video signalUS20050190980 *Apr 25, 2005Sep 1, 2005Bright Walter G.Lossy method for compressing images and videoUS20060239581 *Mar 15, 2006Oct 26, 2006Darren NeumanMethod and system for dynamic contrast stretchUS20070071334 *Apr 10, 2006Mar 29, 2007Canon Kabushiki KaishaImage processing apparatus and methodEP0613294A1Feb 23, 1994Aug 31, 1994Matsushita Electric Industrial Co., Ltd.Gradation correction device and image sensing device therewithEP0957631A1Oct 20, 1998Nov 17, 1999Sony CorporationDisplay device, marker signal forming method, marker signal detection circuit and control signal generation circuitEP1333665A2Jan 27, 2003Aug 6, 2003Nikon CorporationElectronic cameraEP1560417A2Jan 14, 2005Aug 3, 2005Broadcom CorporationSystem and method for clipping values of pixels in one color space so not to exceed the limits of a second color spaceGB2418316A Title not availableWO1995033337A1May 18, 1995Dec 7, 1995Hughes Aircraft CoA method for specifying a video window's boundary coordinates to partition a video signal and compress its componentsWO2000063838A1Apr 14, 2000Oct 26, 2000Izahi CorpAutomatic black level, luminosity and color compensation for digital still images and digital videoWO2001041117A1Nov 15, 2000Jun 7, 2001Koninkl Philips Electronics NvIdentification of the position of a video window to be enhanced within a display signal* Cited by examinerNon-Patent CitationsReference1Dimitrova et al., "On Selecting Video Content Analysis and Filtering", Proceedings of the SPIE, SPIE, vol. 3972, Jan. 26, 2000, pp. 359-368.2European Search Report dated Jan. 14, 2008 in EP Application No. 07252590.0.3European Search Report dated Jan. 7, 2009 in EP Application No. 07252587.6.4European Search Report dated Jan. 7, 2009 in EP Application No. 07252588.4.5European Search Report dated Sep. 25, 2007 in EP Application No. 07252589.2.6Goh, K. H. et al., "Automatic Video Contrast Enhancement", Consumer Electronics, 2004 IEEE International Symposium on Reading, UK, Sep. 1-3, 2004, pp. 359-364.7Partial Search Report dated Oct. 18, 2007 in Application No. 07252590.0.8Search Report and Written Opinion dated Nov. 17, 2008 in Singapore Patent Application No. 0704764-0.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS20130076803 *Sep 20, 2012Mar 28, 2013Lg Display Co., Ltd.Organic light emitting display device and driving method thereof* Cited by examinerClassifications U.S. Classification382/274International ClassificationG06K9/40Cooperative ClassificationH04N5/202European ClassificationH04N5/202Legal EventsDateCodeEventDescriptionApr 28, 2014FPAYFee paymentYear of fee payment: 4Sep 21, 2006ASAssignmentOwner name: GENESIS MICROCHIP INC., CALIFORNIAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NEAL, GREG;REEL/FRAME:018345/0640Effective date: 20060920RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google