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...
回答（3 个）
Friedrich
2011-8-19
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 个评论
Fangjun Jiang
2011-8-19
Oh, are you suggesting the OP to divide his matrix by 255? It's not necessary. im2double() automatically does that.
Friedrich
2011-8-19
Yes im2double does that but Pramod asked for the basic formula. He knows about im2double.
Fangjun Jiang
2011-8-19
Fair enough! No argument from me!
Fangjun Jiang
2011-8-19
By simply dividing all the numbers by 255?
See example:
I1 = reshape(uint8(linspace(1,255,25)),[5 5])
I2 = im2double(I1)
3 个评论
Friedrich
2011-8-19
Little note: you have to cast it as a double first. Otherwise you will get 0 as result, e.g. uint8(10)/255
Fangjun Jiang
2011-8-19
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
2011-8-19
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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2011-8-19
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