How to use IF with @(block_struct) function

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fun2 = @(block_struct) ...
if < 100
std2( * (;
Doesnt work.
I actually want to manipulate individual elements of my block
blocks made of 8x8 values ranging from 0-255
Saud Alfalasi
Saud Alfalasi on 22 Nov 2020
Hi Geoff
blockyImageR = blockproc(redChannel, blockSize, fun);
blockyImageG = blockproc(greenChannel, blockSize, fun);
blockyImageB = blockproc(blueChannel, blockSize, fun);
rgbImage2 = cat(3, blockyImageR, blockyImageG, blockyImageB);
I'm trying to create a method of LSB insertation based on a sequece to do with individual blocks.
Just as a test I'm trying to only change values of numbers in my block according to the values.
the data field is is part of the array with is a 9x9x1 block
I would also like to try and pinpoint the minddle value of my block (coordinates 2,2) and do a quoteince differnce betwen it and the surrounding values.
Ideally what I want to do is not only change values in blocks but also manage the sequence of movement from block to block - example follwing some kind of sequence which results in going from block1 > block 7 > block 27

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Accepted Answer

Athul Prakash
Athul Prakash on 24 Nov 2020
Hi Saud,
Since blockproc uses anonymous functions, you may save your multi-line function into a script, say myFunc.m and then pass @myFunc to your blockproc call.
You can find block_struct structure described in the following doc (under More About section): 'blockproc' Documentation.
You may work out a way to manage the sequence artificially using some of those fields. For example, using block_struct.location to skip processing the 2nd block:
function out = myFunc(block_struct) % size would be 100x100
% skipping the 2nd block.
out =;
% code for processing every other element
Hope it helps!
Saud Alfalasi
Saud Alfalasi on 24 Nov 2020
Edited: Saud Alfalasi on 24 Nov 2020
Blow away, you gave great help. Answer has been accepted. May I ask if you're contactable in any way? I could do with some guidance

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