A method of driving a display device comprising a display panel comprising pixels arranged in a matrix comprising a first display panel region and a second display panel region, a boundary between the first and second display panel regions defining a horizontal center line, the display device further comprising: first data lines (DU1, DU2,.. DUm) positioned in the first display panel region, second data lines (DL1, DL2,.. DLm) positioned in the second display panel region, a first data driver configured to apply grey voltages to the plurality of first data lines (DU1, DU2,..DUm), a second data driver configured to apply grey voltages to the plurality of second data lines (DL1, DL2,..DLm) and a signal controller configured to control the first and the second data drivers (500a, 500b) and comprising a data processor, said data processor being configured to generate image data (DAT1, DAT2) for said first and second data drivers (500a, 500b) by processing an input image signal (IDAT), the method comprising: setting a data processing region comprising pixels in a vicinity of said horizontal center line defined by the boundary between the first and second display panel regions (300a,300b) whereby the first and second display panel regions each comprise respective first and second data processing regions about said horizontal center line; and data processing comprising changing a gray level of data for a portion of the plurality of pixels of the data processing region, characterized by setting a stitch pattern comprising one or more unit patterns, each of the one or more unit patterns comprising a plurality of unit blocks, each of the plurality of unit blocks comprising N pixels in one pixel row, wherein N is equal to or greater than 2, and N is less than the number of pixels of the one pixel row, wherein the unit pattern comprises one or more first unit blocks positioned on the data processing region of the first display region, and one or more second unit blocks positioned on the data processing region of the second display region, and comparing a voltage of a first feedback point with a voltage of a second feedback point resulting from a same corresponding grey level wherein, when a voltage difference detected between the first and second feedback points corresponds to a gray level value, the method further comprises either: subtracting said gray level value from original data of pixels of portions of the first unit blocks and adding said gray level value to original data of pixels of portions of the second unit blocks; or adding said gray level value to original data of pixels of portions of the first unit blocks and subtracting said gray level value from original data of pixels of portions of the second unit blocks. first data lines (DU1, DU2,.. DUm) positioned in the first display panel region, second data lines (DL1, DL2,.. DLm) positioned in the second display panel region, a first data driver configured to apply grey voltages to the plurality of first data lines (DU1, DU2,..DUm), a second data driver configured to apply grey voltages to the plurality of second data lines (DL1, DL2,..DLm) and a signal controller configured to control the first and the second data drivers (500a, 500b) and comprising a data processor, said data processor being configured to generate image data (DAT1, DAT2) for said first and second data drivers (500a, 500b) by processing an input image signal (IDAT), setting a data processing region comprising pixels in a vicinity of said horizontal center line defined by the boundary between the first and second display panel regions (300a,300b) whereby the first and second display panel regions each comprise respective first and second data processing regions about said horizontal center line; and data processing comprising changing a gray level of data for a portion of the plurality of pixels of the data processing region, subtracting said gray level value from original data of pixels of portions of the first unit blocks and adding said gray level value to original data of pixels of portions of the second unit blocks; or adding said gray level value to original data of pixels of portions of the first unit blocks and subtracting said gray level value from original data of pixels of portions of the second unit blocks.