# US 9,437,163 B2 · Methods and apparatuses for increasing the apparent brightness of a display to synchronize at least two monitors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,163 B2 - Document ID: US9437163B2 - Status: Granted - Kind: B2 - Application number: 14/340,008 - Filed: 2014-07-24 - Published: 2014-11-13 - Granted: 2016-09-06 - Earliest claimed: 2007-05-30 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Gabriel Marcu - Web page: https://patentgrep.com/patent/US9437163B2 ## CPC - G09G 5/12: Synchronisation between the display unit and other units, e.g. other display units, video-disc players - G09G 3/20: for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix {no fixed position being assigned to or needed to be assigned to the individual characters or partial characters} - G09G 3/3611: {Control of matrices with row and column drivers} - G09G 2300/02: Composition of display devices - G09G 2320/02: Improving the quality of display appearance - G09G 2320/0271: Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping - G09G 2320/0276: for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction - G09G 2320/0626: for control of overall brightness - G09G 2320/0673: for control of gamma adjustment, e.g. selecting another gamma curve - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) ## Abstract Methods and apparatuses to varying the apparent brightness of a display are described. The change in apparent brightness is accompanied by unchanged in relative contrast, rendering a display with higher or lower brightness while maintaining contrast fidelity. In exemplary embodiments, the signals for the middle tone levels are adjusted to increase or decrease the brightness intensity, while keeping constant the gamma correction. This maintains the relative contrast of images while rendering them at a different brightness. Implementations of the present process include an adjusted gamma correction lookup table, incorporated in the video card to modify the video signal before reaching the display. The present invention can be used for matching the brightness of two or more displays or to provide compensation for variations in display characteristics to ensure consistency in display brightness within a data processing model. ## Claims ### Claim 1 A method to synchronize the brightness for at least two monitors, each monitor comprising a corresponding monitor maximum brightness level, the method comprising: determining a brightness level for synchronizing the brightness for the at least two monitors; adjusting the brightness of at least one monitor to achieve the determined brightness level for synchronizing the at least two monitors, the adjustment comprising: partitioning a signal to the at least one monitor into at least two brightness regions: a highlight region and a middle region; shifting up signal values of the signal for the middle region with a gamma correction of the at least one monitor to increase the brightness of the middle region while preserving the relative contrast of the signal values of the middle region, wherein a range of the middle region is computed to achieve a target luminance, wherein preserving the relative contrast is maintained by keeping substantially constant a shape of a gamma correction curve of the at least one monitor over a substantial portion of the curve, the shifting operation matching the monitor maximum brightness level with the determined brightness level for synchronizing the at least two monitors; and interpolating the signal values for the highlight region to the monitor maximum brightness level. ### Claim 2 (depends on 1) The method as in claim 1 wherein the determined brightness level corresponds to the higher monitor maximum brightness level between the at least two monitors. ### Claim 3 (depends on 1) The method as in claim 1 wherein the determined brightness level corresponds to the lower monitor maximum brightness level between the at least two monitors. ### Claim 4 (depends on 1) The method as in claim 1 wherein the determined brightness level corresponds to a brightness level between the at least two maximum brightness levels of the monitors. ### Claim 5 (depends on 1) The method as in claim 1 wherein a monitor with a lower maximum brightness level is adjusted to the higher maximum brightness level of the other monitor. ### Claim 6 (depends on 1) The method as in claim 1 further comprising a third shadow region wherein the signals within the shadow region are smoothly interpolated to a black level. ### Claim 7 (depends on 1) The method as in claim 1 wherein the middle region comprises from less than 5% brightness level to more than 95% brightness level. ### Claim 8 (depends on 1) The method as in claim 1 wherein the signal values are compensated for gamma correction with the signal values for the middle region being shifted up with a gamma correction based on multiplying only the signal values for the middle region with a factor to increase the brightness while preserving a relative contrast. ### Claim 9 (depends on 1) The method as in claim 1 wherein shifting up uses a look-up table from a video card inputting to the monitor, the look-up table comprising gamma correction. ### Claim 10 (depends on 1) The method as in claim 1 wherein preserving the relative contrast is maintained by keeping substantially constant the shape of the gamma correction of a native response of the at least one monitor. ### Claim 11 (depends on 1) The method as in claim 1 wherein adjusting the brightness of a monitor does not increase the power consumption, wherein the signal to the monitor comprises a gray level signal. ### Claim 12 (depends on 1) The method as in claim 1 wherein the signal to the monitor comprises a plurality of color signals, and the brightness adjustment is applied to the plurality of color signals. ### Claim 13 (depends on 1) The method of claim 1, wherein the highlight region comprises less than 5% of the signal. ### Claim 14 (depends on 6) The method of claim 6, wherein the shadow region comprises less than 5% of the signal.