columns of the third row whose values are 112 and 81 have identical values to those in the preceding frame frame n 510 as is evident in the difference frame 500 yet they are included within the roi mask 540 in fig5 b while pixels in the original frame frame n 1 520 in fig5 a outside the bounding rectangle are not transmitted and may be reconstructed based on the previous frame pixels within the bounding rectangle may be set to the u2018 transparent pixel u2019 this may occur if the bounding rectangle of the roi mask 540 incorporates pixels that have no relative change and are not part of a larger sequence of contiguous pixels with identical values for example in fig5 c frame n 1 520 in example i contains two pixels in the 2 nd and 3 rd columns of the third row that have identical values to those in the preceding frame 112 and 81 respectively since these pixels are not part of a larger sequence of contiguous pixels with identical values their values are adjusted to equal that of the u2018 transparent pixel u2019 labeled u2018 t u2019 in example ii although the pixels in the 2 nd and 3 rd columns of the third row have the same value as the preceding frame being all equal to 50 because they are part of a larger contiguous sequence with identical values in frame n 1 520 that includes the pixel in the 4 th column of the third row their values are not modified the decision whether to set pixels within the region of.