Format to read the segmentation of a graphic design

For each image named filename.png I will make a text file named filename.txt with the following format that would keep the detection information:

4
480 640
345  TL 71231 71232 71234 ...
509  TL 87643 87723 87724 ...
5675 GD 35443 35444 35445 ...
6578 IM 45064 45065 45066 ...

The first line indicated the number of elements. The second line indicates the height and the width of the image. Each line after the text line describes an elements. Entries in each line are separated with a space.

The first entry in each line indicates N, the number of pixels in that segment, the second line indicates the type of the segment (TL: Text Line, GD: Graphic Design, IM: Natural Image). This is followed by N integers each indicating the position of a pixel in the segment. These integers are 1-based linear indicators of the pixels. For example, in a 640x480 (horizontal) image, the top left corner is 1, the bottom right corner is 640*480=307200, the bottom left corner is 480, and the top right corner is 640*480-480+1=306721.