1. A method for detecting open caption text in a video having a plurality of frames and each frame having a plurality of pixels, the method comprising processor implemented steps of: marking location of one or more pixels in a threshold marked buffer if a difference between pixel value of a pixel in an original frame and pixel value of a pixel in a filtered frame is above a first predefined threshold; marking location of one or more pixels in the original frame lying in a high density region by calculating spatial discontinuity at each pixel in a text candidate map buffer; determining a neighborhood size based on a coarse font size, the neighborhood size being a multiple of the coarse font size; determining one or more seed pixels in the threshold marked buffer and the text candidate map buffer, by determining one or more marked pixels in the threshold marked buffer and the text candidate map buffer, having a number of marked pixels within the neighborhood size greater than a second predefined threshold; determining one or more connected components, by determining marked pixels of the threshold marked buffer in a first predefined neighborhood of each seed pixel present in the threshold marked buffer and connecting all the marked pixels in the first predefined neighborhood of each seed pixel in the threshold marked buffer and that seed pixel; determining one or more connected components, by determining marked pixels of the text candidate map buffer in a second predefined neighborhood of each seed pixel present in the text candidate map buffer and connecting all the marked pixels in the second predefined neighborhood of each seed pixel in the text candidate map buffer and that seed pixel; determining one or more valid candidates in the original frame by using the determined one or more connected components, by determining one or more connected components having width to height ratio above a third predefined threshold, and having height within a first predefined range, and having a uniform font width; computing one or more moments of the one or more of the determined one or more valid candidates; determining one or more clusters by clustering one or more of the determined one or more valid candidates together if the font width and moments of the one or more valid candidates are in a second predefined range; determining one or more valid clusters by analyzing the valid candidates within each of the one or more clusters, wherein a valid cluster has spatially neighbouring connected components; determining motion profile of each of one or more frames or fields, wherein the motion profile includes a measure of a displacement of the one or more valid candidates in the one or more valid clusters for consecutive frames or fields; and analyzing the motion profile of all the frames in the video for determining uniformity in the frames by comparing the motion profile of a pair of current frame and previous frame.