This document describes software for 2D block scaling and rotation control. It includes a top level function for scaling and rotating images and describes the dependencies and sub-functions. It focuses on vertical block scaling control, explaining how it determines the number of vertical blocks, initializes starting/ending rows for input/output blocks, and adjusts these values based on scaling factors and scan direction.

1. 2D Block Scaling Control Software
Shereef Shehata

2. Top Level Function for Scaling and rotation
• void Block_scaler_rot (regfield_struc *regfield_ptr, unsigned char
**A_in, unsigned char **R_in, unsigned char **G_in, unsigned char
**B_in, unsigned char **A_out, unsigned char **R_out, unsigned char
**G_out, unsigned char **B_out)
• This function is the top Level scale and rotate function. It is
input is the input image to be scaled and rotated. The output is
the scaled and rotated image.

3. Block_scaler_rot functional dependencies

4. Horizontal Scaler Control
• void horiz_scaler_control (long *H_in_Block_St_col, long
*H_in_Block_End_col, long *H_out_Block_St_col, long
*H_out_Block_End_col, int srcW, int tarW, int H_scan_dir, int
Scale_factor_h, int Inv_scale_h, int H_no_blocks)
• This function will determine the starting/ending column for each block in the
horizontal direction H_in_Block_St_col, H_in_Block_End_col for the input
image to be scaled.
• This function will also determine the starting/ending column for each block
in the horizontal direction H_out_Block_End_col, H_out_Block_End_col for
the output scaled image.

5. Block-scaling control (The notion of pixel index does not depend on the
direction of scan)
tarH
srcH
srcW tarW(H =1,V=1)
(H =1,V=tarH)
(H =tarW,V=1)
(H =1,V=srcH) (H =srcW,V=srcH)
(H =tarW,V=tarH)
(H =1,V=1) (H =srcW,V=1)
5

6. Block-scaling control (Vertical scan down, Horizontal Scan right)
tarW
tarH
srcH
srcW
6

7. Block-scaling control (Vertical scan down, Horizontal scan right)
tarH
tarW
srcH
srcW
7

8. Block-scaling control (Vertical scan down, Horizontal scan left)
tarW
tarH
srcH
srcW
8

9. Block-scaling control (Vertical scan down, Horizontal scan left)
tarH
tarW
srcH
srcW
9

10. Block-scaling control (Vertical scan up, Horizontal scan left)
tarW
tarH
srcH
srcW
10

11. Block-scaling control (Vertical scan up, Horizontal scan left)
tarH
tarW
srcH
srcW
11

12. Block-scaling control (Vertical scan up, Horizontal scan right)
tarW
tarH
srcH
srcW
12

13. Block-scaling control (Vertical scan up, Horizontal scan right)
tarH
tarW
srcH
srcW
13

14. Vertical block-scaling control
out_Blk_sz_v = 32;
V_no_blocks = ceil(tarH ./out_Blk_sz_v)
Determine the vertical number of blocks
Initialize the first row of the first output vertical block based
On the direction of scan
14

15. Vertical Block-scaling control (Vertical number of blocks is the same in
the output and input)
Vert_blox_index =1
Vert_blox_index =
V_no_blocks
Vert_blox_index =1
15

16. Vertical block-scaling control
if (V_scan_dir == 1)
% Vertical scan is Down
V_in_Block_St_row(1) = 1;
V_out_Block_St_row(1) = 1;
else
% Vertical scan is Up
V_in_Block_St_row(1) = srcH;
V_out_Block_St_row(1) = tarH;
end
Initialize the Start row of the first input vertical block based
on the direction of scan
While Scaning target image pixel rows
According to the direction of scan
1<= tar_row<= (tar_H)
Initialize the Start row of the first output vertical block based
On the direction of scan
16

17. Vertical Block-scaling control (Starting vertical row of the first vertical
block for the input and output)
V_in_Block_St_row(1)
V_in_Block_St_row(1) = tarH
V_out_Block_St_row(1)
V_in_Block_St_row(1) = srcH
17

18. Vertical block-scaling control (Determine the output vertical block
boundary)
while (( V_scan_dir ==1) && tar_row <= tarH || (( V_scan_dir ==2) && tar_row >= 1 ) )
% At boundary row of an output vertical block
if ( ((V_scan_dir == 1) && (rem(tar_row,out_Blk_sz_v) == 0 )) || ...
((V_scan_dir == 2) && ( rem(((tarH-tar_row)+1), out_Blk_sz_v) == 0 )) )
While Scaning target image pixel rows
According to the direction of scan
1<= tar_row<= (tar_H)
At each vertical block boundary
of the target image
Compute the vertical block index
18

19. Vertical Block-scaling control (Determine the output vertical block
boundary)
((V_scan_dir == 1) && (rem(tar_row,out_Blk_sz_v) == 0 ))
((V_scan_dir == 2) && ( rem(((tarH-tar_row)+1),
out_Blk_sz_v) == 0 ))
19

20. Vertical block-scaling control (Compute the current vertical block index
depending on the direction of scan)
% compute the current vertical block index
% Vertically Down
if (V_scan_dir == 1)
Vert_Block_Index = floor(tar_row./out_Blk_sz_v);
else
% Vertically Up
Vert_Block_Index = floor(((tarH-tar_row)+1) ./ out_Blk_sz_v);
end
At each vertical block boundary
of the target image do:
Compute the vertical block index
20

21. Vertical Block-scaling control (Compute the output vertical block index)
Vert_Block_Index = 1
Vert_Block_Index = V_no_blocks-1
Vert_Block_Index = V_no_blocks
Vert_Block_Index = V_no_blocks
Vert_Block_Index = V_no_blocks-1
Vert_Block_Index = 1
21

22. Vertical block-scaling control (Compute the end row of the output
vertical block)
% compute the block-end boundary of the current output vertical block
V_out_Block_End_row(Vert_Block_Index) = tar_row;
Compute the vertical block index
Compute the end row of the current output vertical block
22

23. Vertical block-scaling control (Compute the end row of the output
vertical block)
V_out_Block_End_row(1)
V_out_Block_End_row(V_no_blocks-1)
V_out_Block_End_row(V_no_blocks)=tarH
V_out_Block_End_row(V_no_blocks)=1
V_out_Block_End_row(V_no_blocks-1)
V_out_Block_End_row(1)
23

24. Vertical block-scaling control (Compute the end row of the current input
vertical block, for vertical down scan)
if(V_scan_dir ==1)
if(Inv_scale_v >= 1)
% down scaling
V_in_Block_End_row(Vert_Block_Index) = ceil(tar_row * Inv_scale_v);
else
V_in_Block_End_row(Vert_Block_Index) = ceil(tar_row * Inv_scale_v)+1;
end
if ( V_in_Block_End_row(Vert_Block_Index) > srcH)
V_in_Block_End_row(Vert_Block_Index) = srcH;
end
Compute the end row of the current output vertical block
compute the block-end boundary of the current input
vertical block (Vertical down scan)
24

25. Vertical block-scaling control (Compute the end row of the current input
vertical block, for vertical down scan) Down-Scaling
V_in_Block_End_row(1)
V_in_Block_End_row(2)
V_in_Block_End_row(V_no_blocks-1)
V_in_Block_End_row(V_no_blocks)
25

26. Vertical block-scaling control (Compute the end row of the current input
vertical block, for vertical down scan) Up-Scaling
V_in_Block_End_row(1)
V_in_Block_End_row(2)
V_in_Block_End_row(V_no_blocks-1)
V_in_Block_End_row(V_no_blocks)
26

27. Vertical block-scaling control (Compute the end row of the current input
vertical block, for vertical up scan)
else
% Vertical Up Scan
if(Inv_scale_v >= 1)
% down scaling
V_in_Block_End_row(Vert_Block_Index) = srcH - (ceil( ((tarH-tar_row)+1) * Inv_scale_v) ) + 1;
else
V_in_Block_End_row(Vert_Block_Index) = srcH - (ceil( ((tarH-tar_row)+1) * Inv_scale_v) ) ;
end
if ( V_in_Block_End_row(Vert_Block_Index) < 1)
V_in_Block_End_row(Vert_Block_Index) = 1;
end
end
Compute the end row of the current output vertical block
compute the block-end boundary of the current input
vertical block (Vertical up scan)
27

28. Vertical block-scaling control (Compute the end row of the current input
vertical block, for vertical up scan) Down-Scaling
V_in_Block_End_row(1)
V_in_Block_End_row(2)
V_in_Block_End_row(V_no_blocks-1)
V_in_Block_End_row(V_no_blocks)
28

29. Vertical block-scaling control (Compute the end row of the current input
vertical block, for vertical up scan) Up-Scaling
V_in_Block_End_row(1)
V_in_Block_End_row(2)
V_in_Block_End_row(V_no_blocks-1)
V_in_Block_End_row(V_no_blocks)
29

30. Vertical block-scaling control (Compute the start row of the next output
vertical block)
if (V_scan_dir == 1)
% Vertically Down
V_out_Block_St_row(Vert_Block_Index+1) = V_out_Block_End_row(Vert_Block_Index)+1;
if (V_out_Block_St_row(Vert_Block_Index+1) > tarH)
V_out_Block_St_row(Vert_Block_Index+1) = tarH;
end
else
% Vertically Up
V_out_Block_St_row(Vert_Block_Index+1) = V_out_Block_End_row(Vert_Block_Index)-1;
if (V_out_Block_St_row(Vert_Block_Index+1) < 1)
V_out_Block_St_row(Vert_Block_Index+1) = 1;
end
end
compute the block-end boundary of the current input
vertical block (Vertical down/up scan)
compute the block-start boundary of the next output
vertical block (Vertical down/up scan)
30

31. Vertical block-scaling control (Compute the start row of the output
vertical block)
V_out_Block_St_row(1) = 1
V_out_Block_St_row(V_no_blocks-1)
V_out_Block_St_row(V_no_blocks)
V_out_Block_St_row(V_no_blocks)
V_out_Block_St_row(V_no_blocks-1)
V_out_Block_St_row(1) = tarH
31

32. Vertical block-scaling control (Compute the start row of the next input
vertical block, for vertical down scan)
if(V_scan_dir ==1)
if(Inv_scale_v >= 1)
% down scaling
V_in_Block_St_row(Vert_Block_Index+1) = V_in_Block_End_row(Vert_Block_Index);
else
% Up scaling
V_in_Block_St_row(Vert_Block_Index+1) = V_in_Block_End_row(Vert_Block_Index)-1;
end
if (V_in_Block_St_row(Vert_Block_Index+1) > srcH)
V_in_Block_St_row(Vert_Block_Index+1) = srcH;
end
compute the block-start boundary of the current output
vertical block (Vertical down/up scan)
compute the block-start boundary of the next input
vertical block (Vertical down scan)
32

33. Vertical block-scaling control (Compute the start row of the input
vertical block, for vertical down scan) Down-Scaling
V_in_Block_St_row(1)
V_in_Block_St_row(2)
V_in_Block_St_row(V_no_blocks-1)
V_in_Block_St_row(V_no_blocks)
33

34. Vertical block-scaling control (Compute the start row of the input
vertical block, for vertical down scan) Up-Scaling
V_in_Block_St_row(1)
V_in_Block_St_row(2)
V_in_Block_St_row(V_no_blocks-1)
V_in_Block_St_row(V_no_blocks)
34

35. Vertical block-scaling control (Compute the start row of the next input
vertical block, for vertical up scan)
else
if (Inv_scale_v >= 1)
% down scale
V_in_Block_St_row(Vert_Block_Index+1) = V_in_Block_End_row(Vert_Block_Index);
else
% compute the block-start boundary of the current input vertical block
V_in_Block_St_row(Vert_Block_Index+1) = V_in_Block_End_row(Vert_Block_Index)+1;
end
if (V_in_Block_St_row(Vert_Block_Index+1) < 1)
V_in_Block_St_row(Vert_Block_Index+1) = 1;
end
end
compute the block-start boundary of the current output
vertical block (Vertical down/up scan)
compute the block-start boundary of the next input
vertical block (Vertical up scan)
35

36. Vertical block-scaling control (Compute the start row of the input
vertical block, for vertical up scan) Down-Scaling
V_in_Block_ST_row(1)
V_in_Block_St_row(2)
V_in_Block_St_row(V_no_blocks-1)
V_in_Block_St_row(V_no_blocks)
36

37. Vertical block-scaling control (Compute the start row of the input
vertical block, for vertical up scan) Up-Scaling
V_in_Block_End_row(1)
V_in_Block_End_row(2)
V_in_Block_End_row(V_no_blocks-1)
V_in_Block_End_row(V_no_blocks)
37

38. Vertical block-scaling control (Adjust the start row of the next input
vertical block, if the current input block has no vertical pixel fraction)
if (V_scan_dir == 1)
% Vertical down
if ( ( ceil(tar_row * Inv_scale_v) - (tar_row * Inv_scale_v)) == 0)
V_in_Block_St_row(Vert_Block_Index+1) = V_in_Block_St_row(Vert_Block_Index+1) + 1;
end
if (V_in_Block_St_row(Vert_Block_Index+1) > srcH)
V_in_Block_St_row(Vert_Block_Index+1) = srcH;
end
else
% Vertical Up
if ( ( (ceil( ((tarH-tar_row)+1) * Inv_scale_v) ) - ( ((tarH-tar_row)+1) * Inv_scale_v) ) == 0)
V_in_Block_St_row(Vert_Block_Index+1) = V_in_Block_St_row(Vert_Block_Index+1) - 1;
end
if (V_in_Block_St_row(Vert_Block_Index+1) < 1)
V_in_Block_St_row(Vert_Block_Index+1) = 1;
end
end
compute the block-start boundary of the current input
vertical block (Vertical down/up scan)
Adjust the block-start boundary of the current input
vertical block if the real current vertical block
ended on a pixel boundary (Vertical down/up scan)
38

39. Vertical block-scaling control (Adjust the start row of the next input vertical block, if the
current input block has no vertical pixel fraction) Vertical down scan, Down-Scaling
V_in_Block_St_row(1)
V_in_Block_St_row(2)
V_in_Block_St_row(V_no_blocks-1)
V_in_Block_St_row(V_no_blocks)
39

40. Vertical block-scaling control (Adjust the start row of the next input vertical block, if the
current input block has no vertical pixel fraction) Vertical down scan, Up-Scaling
V_in_Block_St_row(1)
V_in_Block_St_row(2)
V_in_Block_St_row(V_no_blocks-1)
V_in_Block_St_row(V_no_blocks)
40

41. Vertical block-scaling control (Adjust the start row of the next input vertical block, if the
current input block has no vertical pixel fraction) Vertical up scan, Down-Scaling
V_in_Block_ST_row(1)
V_in_Block_St_row(2)
V_in_Block_St_row(V_no_blocks-1)
V_in_Block_St_row(V_no_blocks)
41

42. Vertical block-scaling control (Adjust the start row of the next input vertical block, if the
current input block has no vertical pixel fraction) Vertical up scan, Up-Scaling
V_in_Block_ST_row(1)
V_in_Block_St_row(2)
V_in_Block_St_row(V_no_blocks-1)
V_in_Block_St_row(V_no_blocks)
42