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## Image Geometry Transform - rotation direction

Beginner
147 Views
Hi all !
I have a problem using the ippiRotate_xxx methods.
with 8u_C1R and 8u_C3R the direction is clockwise
with 8u_C4R the direction is counterclockwise
I use the IPP 7.01 library.
Is it a normal behavior ?
Thanks
Mike
4 Replies
New Contributor I
147 Views
HelloMike,

Could you please provide a sample code with more information about your problem?
What is interpolation method? Whatis image size? Angle?

Thanks,
Beg
Employee
147 Views

Hi Beg,

You can also run the IPP ippiDemo.exe at Intel\IPP\6.1.6.056\ia32\demo\, and see if this is a code error, or a bug related with IPP.

Regards,
Chao
New Contributor I
147 Views
Please take a look at thepictures obtained by using ippiDemo application.
Rotation of (30) and (360-30) degrees.

What is wrong ?

Thanks,
Beg
Beginner
147 Views
Hi all,
may be I made a mistake but I used the same code with ipp 3.0 and I have never had any error.
here is my code :
double dAngle = 45;
double dBounds[2][2];
IppiRect rect = {0, 0, 640, 480};
IppStatus status = ippiGetRotateBound(rect, dBounds, dAngle, 0, 0);
IppiRect rectOutput = {0, 0,dBounds[1][0] - dBounds[0][0],dBounds[1][1] - dBounds[0][1]};
IppiSize sizeInput = {rect.width, rect.height};
status = ippiRotate_8u_C3R(pInputBuffer, sizeInput, iStrideIn, rect,
pOutputBuffer, iStrideOut, rectOutput,
dAngle, -dBounds[0][0], -dBounds[0][1], IPPI_INTER_LINEAR);
status = ippiRotate_8u_C4R(
pInputBuffer, sizeInput, iStrideIn, rect,
pOutputBuffer, iStrideOut, rectOutput,
dAngle,-dBounds[0][0], -dBounds[0][1], IPPI_INTER_LINEAR);
(the pInputBuffer for the 2 above versions are respectively in 24bits and 32bits)
8u_C3R and 8u_C1R rotate in clockwise direction and 8u_C4R in counterclockwise direction
I have the same behavior between 8u_C4R and 8u_AC4R.
Later, if necessary, I will put a test program with full c++ source code. For the moment I haven't the time to do it. To patch the problem I invert the angle in 8 and 24 bits.
I made the tests with ippiDemo, I have the same rotation direction with 24 et 32bits pictures but in clockwise direction (the inverse as noticed in documentation).
Thanks