What is the formula to convert uint8 image to double format ?

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Hi friends, i want to convert a uint8 format image to double format.I have got command 'im2double' for that. But i want to know the basic formula for converting that.
For ex : i want to represent intensity level 256 to double format which is represented in [0 1]. please help. Thanks...

Risposte (3)

Friedrich
Friedrich il 19 Ago 2011
Hi,
simply cast it as double and than divide by the maximum number of the datatype. In your case (uint8) its 255. So when your image is A do
double(A)/255
or more general
double(A)/intmax(class(A))
  3 Commenti
Friedrich
Friedrich il 19 Ago 2011
Yes im2double does that but Pramod asked for the basic formula. He knows about im2double.

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Fangjun Jiang
Fangjun Jiang il 19 Ago 2011
By simply dividing all the numbers by 255?
See example:
I1 = reshape(uint8(linspace(1,255,25)),[5 5])
I2 = im2double(I1)
  3 Commenti
Fangjun Jiang
Fangjun Jiang il 19 Ago 2011
What do you mean? The code I quoted is from help im2double. The OP is asking how im2double is able to convert 0~255 to 0~1. I am guessing it just divides by 255, like you guessed.
Friedrich
Friedrich il 19 Ago 2011
My comment is related to your statement: "By simply dividing all the numbers by 255?" Simply diving is not enough you have to cast first.

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Pramod Bhat
Pramod Bhat il 19 Ago 2011
Thanks alot friends. ..). thanq. i understood.

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