polyfit in matlab with differrent types of data

Question

When reading an image, the inputs considered for polyfit are different types. one is "uint8" while the other is "double" (their size is the same, <1x384>) Could you please give me a hint that how I can solve it?

its errors are shown below while I haven't used TIMES in polyfit:

Error using * MTIMES is not fully supported for integer classes. At least one input must be scalar. To compute elementwise TIMES, use TIMES (.*) instead.

Error in polyfit p = R(Q'*y); % Same as p = V\y;

How Can I convert it to unit8? (in other case, its result is not adequate for my script)

This question requires clarification. Post more details regarding error messages and code. — Buck Thorn
You can convert between data types, for instance with double or unit8. — Buck Thorn
Might want to take a look at this: stackoverflow.com/questions/17924743/… — Buck Thorn
Why can't you use double? I would convert to double before processing, and if necessary (and possible) convert a result to uint8 — Buck Thorn

Buck Thorn Buck Thorn · Accepted Answer · 2013-08-01T11:46:28

To convert a type double to uint8 you can do the following:

b = [1:10]; % <-- type double
a = uint8(b); % <-- convert to uint8

whos a 
  Name      Size                    Bytes  Class

  a         1x1                         1  uint8 array

Grand total is 1 element using 1 bytes

To do the reverse:

a = uint8([1:10]); % <-- convert to uint8
b = double(a); % <-- type double

whos b
  Name      Size                    Bytes  Class

  b         1x10                       80  double array

Grand total is 10 elements using 80 bytes

Type uint8 variables are unsigned integers (>=0).

Some operations don't work with them, such as A\b.

Before attempting your operations with the input images, convert them to double as follows:

im_double = double(im_uint8);

where im_uint8 is the original image.

polyfit in matlab with differrent types of data

1 Answers