i am working on image compression and my code gives the error (Dot indexing is not supported for variables of this type). Could anyone help me on the reason why?

part of the code can be seen below

% apply DCT on 8x8 blocks of the image, and re-order the coefficients

dct_result = blkproc(image, [8 8], @(block_struct) zigzag(dct2(block_struct.data)));

% for each block, set the last n coefficients to zero

for i = 1:m/8

for j = 1:n/8

start_index = 64 - n + 1;

dct_result(start_index:end, start_index:end, i, j) = 0;

end

end

% apply inverse DCT on each block of coefficients

idct_result = blkproc(dct_result, [8 8], @(block_struct) idct2(izigzag(block_struct.data)));

The erroe also says

Dot indexing is not supported for variables of this type.

Error in dc>@(block_struct)zigzag(dct2(block_struct.data)) (line 17)

dct_result = blkproc(image, [8 8], @(block_struct) zigzag(dct2(block_struct.data)));

Answer 1

[Amit Dhakite]

Hi Yonta,

As per my understanding, you are trying to block process the images using blkproc function.

It is not recommended to use blkproc, instead you can use blockproc, which will remove the error related to dot indexing.

To know more about blockproc, kindly refer to the following link:

https://www.mathworks.com/help/images/ref/blockproc.html