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carrying out simple functions on all cells within an array

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Optical_Stress
Optical_Stress on 6 Apr 2017
Commented: Optical_Stress on 6 Apr 2017
Hi,
I have a 5x1 cell containing 'images' (arrays of their intensities). I want to carry out a 'normalisation'. I want to divide the every array in the cell by a constant, this has been successful using:
Normalised_Cell=cellfun(@(v) v./N,B,'UniformOutput',false)
N is the largest value in the first array.
However, the arrays are returning 0 and not the decimal values. For example, If i have a maximum of 180 and the first cell contains 3 (or 50 or 100), the matrix will show 0 instead of 3/180. I suspect that this is due to the fact that the arrays in the cell are uint8. But i'm not sure how to go about fixing this.
I then want to square-root the values, and following that take the inverse sine.
Will cellfun suffice when applying inverse sin to these uint values?

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Accepted Answer

Jan
Jan on 6 Apr 2017
Edited: Jan on 6 Apr 2017
Use double instead:
Normalised_Cell = cellfun(@(v) double(v) ./ double(N), B, 'UniformOutput', false)

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Optical_Stress
Optical_Stress on 6 Apr 2017
Thanks, why has this done that? I would have expected my Uint8 matrix to do the same, since the values are still less than the Uint8 limit.
Jan
Jan on 6 Apr 2017
Try it:
uint8(3) / uint8(180)
This is smaller than 1 and the next possible value is uint8(0). For arithmetic operations it might be useful to convert all images by im2double at first.
Optical_Stress
Optical_Stress on 6 Apr 2017
Yeah, just read about uint8, makes a lot more sense now, thanks.

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